Sample records for x-ray attenuation coefficient

  1. Improved techniques for measuring x-ray mass attenuation coefficients

    NASA Astrophysics Data System (ADS)

    de Jonge, Martin D.; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi N. M...

    2006-04-01

    We apply the x-ray extended-range technique (XERT) to measure mass attenuation coefficients over one order of magnitude more accurately than previously reported in the literature. We describe the application of the XERT to the investigation of systematic effects due to harmonic energy components in the x-ray beam, scattering and fluorescence from the absorbing sample, the bandwidth of the x-ray beam, and thickness variations across the absorber. The high-accuracy measurements are used for comparison with different calculations of mass attenuation coefficients, and to identify particular regions where these calculations fail.

  2. Improved techniques for measuring x-ray mass attenuation coefficients

    NASA Astrophysics Data System (ADS)

    de Jonge, Martin D.; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi

    2004-10-01

    We have applied the x-ray extended-range technique (XERT) to measure mass attenuation coefficients over one order of magnitude more accurately than previously reported in the literature. We describe here the application of the XERT to the investigation of a number of systematic effects which has enabled us to ensure that these recent measurements are free from systematic error. In particular we describe our techniques for quantifying the effects of harmonic components in the x-ray beam, scattering and fluorescence from the absorbing sample, the bandwidth of the x-ray beam, and thickness variations across the absorber.

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

    SciTech Connect

    Chantler, C.T.; Islam, M.T.; Rae, N.A.; Tran, C.Q.; Glover, J.L.; Barnea, Z. (La Trobe); (Melbourne)

    2012-09-25

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

  4. X-Ray Mass Attenuation Coefficient of Silicon: Theory versus Experiment

    NASA Astrophysics Data System (ADS)

    Tran, C. Q.; Chantler, C. T.; Barnea, Z.

    2003-06-01

    We compare new experimental x-ray total mass attenuation coefficients of silicon obtained with the x-ray extended-range technique (XERT) from 5 to 20keV with theoretical calculations and earlier experimental measurements over a 5 to 50keV energy range. The accuracy of between 0.27% and 0.5% of the XERT data allows us to probe alternate atomic and solid state wave function calculations and to test dominant scattering mechanisms. Discrepancies between experimental results and theoretical computations of the order of 5% are discussed in detail. No single theoretical computation is currently able to reproduce the experimental results over the entire 5 to 50keV energy range investigated.

  5. X-ray mass attenuation coefficient of silicon: theory versus experiment.

    PubMed

    Tran, C Q; Chantler, C T; Barnea, Z

    2003-06-27

    We compare new experimental x-ray total mass attenuation coefficients of silicon obtained with the x-ray extended-range technique (XERT) from 5 to 20 keV with theoretical calculations and earlier experimental measurements over a 5 to 50 keV energy range. The accuracy of between 0.27% and 0.5% of the XERT data allows us to probe alternate atomic and solid state wave function calculations and to test dominant scattering mechanisms. Discrepancies between experimental results and theoretical computations of the order of 5% are discussed in detail. No single theoretical computation is currently able to reproduce the experimental results over the entire 5 to 50 keV energy range investigated. PMID:12857162

  6. An improvement to the full-foil mapping technique for high accuracy measurement of X-ray mass attenuation coefficients

    NASA Astrophysics Data System (ADS)

    Rae, Nicholas A.; Glover, Jack L.; Chantler, Christopher T.

    2010-07-01

    The limiting uncertainty in recent high accuracy measurements of the mass attenuation coefficient is the measurement of the integrated column density. An improvement in the design of the absorption foil holder is described which reduces the integrated column density uncertainty. The new design allows the edges of the foil to be more accurately mapped by the X-ray beam by reducing the largest source of uncertainty in the foil mapping: the uncertainty in the points along the foil edge. The method is shown to reduce the uncertainty in measurements of the mass attenuation coefficient of zinc foils. The reduced uncertainty in the full-foil mapping will allow the X-ray Extended Range Technique (XERT) to be applied to small non-metallic absorption foils more accurately.

  7. Measurement of X-ray mass attenuation coefficients in biological and geological samples in the energy range of 7-12keV.

    PubMed

    Trunova, Valentina; Sidorina, Anna; Kriventsov, Vladimir

    2014-10-17

    Information about X-ray mass attenuation coefficients in different materials is necessary for accurate X-ray fluorescent analysis. The X-ray mass attenuation coefficients for energy of 7-12keV were measured in biological (Mussel and Oyster tissues, blood, hair, liver, and Cabbage leaves) and geological (Baikal sludge, soil, and Alaskite granite) samples. The measurements were carried out at the EXAFS Station of Siberian Synchrotron Radiation Center (VEPP-3). Obtained experimental mass attenuation coefficients were compared with theoretical values calculated for some samples. PMID:25464176

  8. Analysis of X-ray absorption fine structure using absolute X-ray mass attenuation coefficients: Application to molybdenum

    NASA Astrophysics Data System (ADS)

    Smale, L. F.; Chantler, C. T.; de Jonge, M. D.; Barnea, Z.; Tran, C. Q.

    2006-11-01

    XAFS structures are solved routinely and hundreds of publications appear per annum. Limitations in theoretical predictions and XAFS analytical frameworks lead to significant uncertainty in results. This impairs structural predictions and prevents ab initio determination. The highest accuracy experimental data have been obtained using the XERT and the most popular technique to analyse the structure. We apply an accurate ?2 fitting procedure to the molybdenum attenuation data including error propagation and improve the XAFS determinations by between 5% and 70%.

  9. Measurement of the x-ray mass attenuation coefficients of gold in the 38?50-keV energy range

    SciTech Connect

    Islam, M.T.; Rae, N.A.; Glover, J.L.; Barnea, Z.; de Jonge, M.D.; Tran, C.Q.; Wang, J.; Chantler, C.T. (Melbourne)

    2010-11-12

    We used synchrotron x rays to measure the x-ray mass attenuation coefficients of gold at nine energies from 38 to 50 keV with accuracies of 0.1%. Our results are much more accurate than previous measurements in this energy range. A comparison of our measurements with calculated mass attenuation coefficients shows that our measurements fall almost exactly midway between the XCOM and FFAST calculated theoretical values, which differ from one another in this energy region by about 4%, even though the range includes no absorption edge. The consistency and accuracy of these measurements open the way to investigations of the x-ray attenuation in the region of the L absorption edge of gold.

  10. Measurement of the X-ray mass attenuation coefficients of silver in the 5-20?keV range.

    PubMed

    Islam, M Tauhidul; Tantau, Lachlan J; Rae, Nicholas A; Barnea, Zwi; Tran, Chanh Q; Chantler, Christopher T

    2014-03-01

    The X-ray mass attenuation coefficients of silver were measured in the energy range 5-20?keV with an accuracy of 0.01-0.2% on a relative scale down to 5.3?keV, and of 0.09-1.22% on an absolute scale to 5.0?keV. This analysis confirms that with careful choice of foil thickness and careful correction for systematics, especially including harmonic contents at lower energies, the X-ray attenuation of high-Z elements can be measured with high accuracy even at low X-ray energies (<6?keV). This is the first high-accuracy measurement of X-ray mass attenuation coefficients of silver in the low energy range, indicating the possibility of obtaining high-accuracy X-ray absorption fine structure down to the L1 edge (3.8?keV) of silver. Comparison of results reported here with an earlier data set optimized for higher energies confirms accuracy to within one standard error of each data set collected and analysed using the principles of the X-ray extended-range technique (XERT). Comparison with theory shows a slow divergence towards lower energies in this region away from absorption edges. The methodology developed can be used for the XAFS analysis of compounds and solutions to investigate structural features, bonding and coordination chemistry. PMID:24562564

  11. X-Ray Attenuation Cell

    Microsoft Academic Search

    D. Ryutov; A. Toor

    2000-01-01

    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

  12. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60keV

    Microsoft Academic Search

    Martin D. de Jonge; Chanh Q. Tran; Christopher T. Chantler; Zwi Barnea; Bipin B. Dhal; David Paterson; Elliot P. Kanter; Stephen H. Southworth; Linda Young; Mark A. Beno; Jennifer A. Linton; Guy Jennings

    2007-01-01

    We use the x-ray extended-range technique (XERT) [C. T. Chantler , Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60keV to 0.04-3% accuracy, and typically in the range 0.1-0.2% . Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and

  13. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60 keV

    Microsoft Academic Search

    Martin D. de Jonge; Chanh Q. Tran; Christopher T. Chantler; Zwi Barnea; Bipin B. Dhal; David Paterson; Elliot P. Kanter; Stephen H. Southworth; Linda Young; Mark A. Beno; Jennifer A. Linton; Guy Jennings

    2007-01-01

    We use the x-ray extended-range technique (XERT) [C. T. Chantler et al., Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60 keV to 0.04-3 % accuracy, and typically in the range 0.1-0.2 %. Measurements made over an extended range of the measurement parameter space are critically examined to

  14. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60keV

    NASA Astrophysics Data System (ADS)

    de Jonge, Martin D.; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi; Dhal, Bipin B.; Paterson, David; Kanter, Elliot P.; Southworth, Stephen H.; Young, Linda; Beno, Mark A.; Linton, Jennifer A.; Jennings, Guy

    2007-03-01

    We use the x-ray extended-range technique (XERT) [C. T. Chantler , Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60keV to 0.04-3% accuracy, and typically in the range 0.1-0.2% . Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and correct a number of potential experimental systematic errors. These results represent the most extensive experimental data set for tin and include absolute mass attenuation coefficients in the regions of x-ray absorption fine structure, extended x-ray absorption fine structure, and x-ray absorption near-edge structure. The imaginary component of the atomic form factor f2 is derived from the photoelectric absorption after subtracting calculated Rayleigh and Compton scattering cross sections from the total attenuation. Comparison of the result with tabulations of calculated photoelectric absorption coefficients indicates that differences of 1-2% persist between calculated and observed values.

  15. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60 keV

    SciTech Connect

    Jonge, Martin D. de; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi; Dhal, Bipin B.; Paterson, David; Kanter, Elliot P.; Southworth, Stephen H.; Young, Linda; Beno, Mark A.; Linton, Jennifer A.; Jennings, Guy [X-Ray Operations and Research, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); School of Physics, University of Melbourne, Victoria 3010 (Australia); Australian Synchrotron Project, Major Projects Victoria, 800 Blackburn Road, Clayton, Victoria 3168 (Australia); Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); BESSRC-CAT, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2007-03-15

    We use the x-ray extended-range technique (XERT) [C. T. Chantler et al., Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60 keV to 0.04-3 % accuracy, and typically in the range 0.1-0.2 %. Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and correct a number of potential experimental systematic errors. These results represent the most extensive experimental data set for tin and include absolute mass attenuation coefficients in the regions of x-ray absorption fine structure, extended x-ray absorption fine structure, and x-ray absorption near-edge structure. The imaginary component of the atomic form factor f{sub 2} is derived from the photoelectric absorption after subtracting calculated Rayleigh and Compton scattering cross sections from the total attenuation. Comparison of the result with tabulations of calculated photoelectric absorption coefficients indicates that differences of 1-2 % persist between calculated and observed values.

  16. Micrometry combined with profile mapping for the absolute measurement of Integrated Column Density (ICD) and for accurate X-ray mass attenuation coefficients using XERT

    NASA Astrophysics Data System (ADS)

    Islam, M. Tauhidul; Rae, Nicholas A.; Glover, Jack L.; Barnea, Zwi; Chantler, Christopher T.

    2010-07-01

    Absolute values of the column densities [?t]c of four gold foils were measured using micrometry combined with the 2D X-ray attenuation profile. The absolute calibration of [?t]c was made with a reference foil and the [?t]c of other foils were determined following the thickness transfer method. By this method, we obtain absolute calibration to 0.1% or better which was not possible using only the X-ray map of a single foil over its central region.

  17. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of molybdenum over the 13.5-41.5-keV energy range

    NASA Astrophysics Data System (ADS)

    de Jonge, Martin D.; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi; Dhal, Bipin B.; Cookson, David J.; Lee, Wah-Keat; Mashayekhi, Ali

    2005-03-01

    We use the x-ray extended-range technique (XERT) [Chantler , Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of molybdenum in the x-ray energy range of 13.5-41.5keV to 0.02-0.15 % accuracy. Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and correct where necessary a number of experimental systematic errors. These results represent the most extensive experimental data set for molybdenum and include absolute mass attenuation coefficients in the regions of the x-ray absorption fine structure (XAFS) and x-ray-absorption near-edge structure (XANES). The imaginary component of the atomic form-factor f2 is derived from the photoelectric absorption after subtracting calculated Rayleigh and Compton scattering cross sections from the total attenuation. Comparison of the result with tabulations of calculated photoelectric absorption coefficients indicates that differences of 1-15 % persist between the calculated and observed values.

  18. X-Ray Attenuation and Absorption for Materials of Dosimetric Interest

    National Institute of Standards and Technology Data Gateway

    SRD 126 X-Ray Attenuation and Absorption for Materials of Dosimetric Interest (Web, free access)   Tables and graphs of the photon mass attenuation coefficient and the mass energy-absorption coefficient are presented for all of the elements Z = 1 to 92, and for 48 compounds and mixtures of radiological interest. The tables cover energies of the photon (x-ray, gamma ray, bremsstrahlung) from 1 keV to 20 MeV.

  19. X-ray attenuation properties of stainless steel (u)

    SciTech Connect

    Wang, Lily L [Los Alamos National Laboratory; Berry, Phillip C [Los Alamos National Laboratory

    2009-01-01

    Stainless steel vessels are used to enclose solid materials for studying x-ray radiolysis that involves gas release from the materials. Commercially available stainless steel components are easily adapted to form a static or a dynamic condition to monitor the gas evolved from the solid materials during and after the x-ray irradiation. Experimental data published on the x-ray attenuation properties of stainless steel, however, are very scarce, especially over a wide range of x-ray energies. The objective of this work was to obtain experimental data that will be used to determine how a poly-energetic x-ray beam is attenuated by the stainless steel container wall. The data will also be used in conjunction with MCNP (Monte Carlos Nuclear Particle) modeling to develop an accurate method for determining energy absorbed in known solid samples contained in stainless steel vessels. In this study, experiments to measure the attenuation properties of stainless steel were performed for a range of bremsstrahlung x-ray beams with a maximum energy ranging from 150 keV to 10 MeV. Bremsstrahlung x-ray beams of these energies are commonly used in radiography of engineering and weapon components. The weapon surveillance community has a great interest in understanding how the x-rays in radiography affect short-term and long-term properties of weapon materials.

  20. Effective x-ray attenuation measurements with full field digital mammography

    SciTech Connect

    Heine, John J.; Behera, Madhusmita [The H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, Florida 33612-4799 (United States)

    2006-11-15

    This work shows that effective x-ray attenuation coefficients may be estimated by applying Beer's Law to phantom image data acquired with the General Electric Senographe 2000D full field digital mammography system. Theoretical developments are provided indicating that an approximate form of the Beer's relation holds for polychromatic x-ray beams. The theoretical values were compared with experimentally determined measured values, which were estimated at various detector locations. The measured effective attenuation coefficients are in agreement with those estimated with theoretical developments and numerical integration. The work shows that the measured quantities show little spatial variation. The main ideas are demonstrated with polymethylmethacrylate and breast tissue equivalent phantom imaging experiments. The work suggests that the effective attenuation coefficients may be used as known values for radiometric standardization applications that compensate for the image acquisition influences. The work indicates that it is possible to make quantitative attenuation coefficient measurements from a system designed for clinical purposes.

  1. Ultrashort x-ray pulse propagation through resonant attenuating media

    NASA Astrophysics Data System (ADS)

    Chukhovskii, F. N.; Teubner, U.; Föautrster, E.

    1997-02-01

    The propagation of ultrashort x-ray pulses through a resonant attenuating two-level atom medium is investigated on the basis of the temporal point-source (the Green-function) formalism. A general case of the small-area pulse (SAP) approximation of a traveling coherent wave is considered. The patterns of the SAP envelope E(t,z) and energy U(z) evolution within the medium are calculated in the cases of incident Lorentzian and exponential pulses and their dependence on the temporal bandwidth ?band in comparison with the total dissipative relaxation time (lifetime) T2 . It is shown that if ?band is the same order or smaller than T2 , the reshaping (oscillations) of the pulse envelope and/or low energy-loss effects occur in accord with the general conclusions pointed out by Crisp [Phys. Rev. A 1, 1604 (1970)] in the case of the SAP for coherent light traveling through a resonant medium. The experimental conditions for the observation of penetration effects of the SAP of x rays are discussed. Based on the theoretical study, it is found that an ultrashort x-ray pulse emitted by an ultrashort laser-produced plasma propagates through thin resonant medium foils with low energy loss.

  2. Sparse signal reconstruction from polychromatic X-ray CT measurements via mass attenuation discretization

    SciTech Connect

    Gu, Renliang; Dogandži?, Aleksandar [Iowa State University, Center for Nondestructive Evaluation, 1915 Scholl Road, Ames, IA 50011 (United States)

    2014-02-18

    We propose a method for reconstructing sparse images from polychromatic x-ray computed tomography (ct) measurements via mass attenuation coefficient discretization. The material of the inspected object and the incident spectrum are assumed to be unknown. We rewrite the Lambert-Beer’s law in terms of integral expressions of mass attenuation and discretize the resulting integrals. We then present a penalized constrained least-squares optimization approach for reconstructing the underlying object from log-domain measurements, where an active set approach is employed to estimate incident energy density parameters and the nonnegativity and sparsity of the image density map are imposed using negative-energy and smooth ?{sub 1}-norm penalty terms. We propose a two-step scheme for refining the mass attenuation discretization grid by using higher sampling rate over the range with higher photon energy, and eliminating the discretization points that have little effect on accuracy of the forward projection model. This refinement allows us to successfully handle the characteristic lines (Dirac impulses) in the incident energy density spectrum. We compare the proposed method with the standard filtered backprojection, which ignores the polychromatic nature of the measurements and sparsity of the image density map. Numerical simulations using both realistic simulated and real x-ray ct data are presented.

  3. Estimating photon interaction coefficients from single energy x-ray CT

    NASA Astrophysics Data System (ADS)

    Midgley, S. M.

    2012-12-01

    Single energy x-ray analysis is explored in the context of computed tomography (CT), whereby Hounsfield numbers (HN) are used to estimate electron density Ne and parameters that describe composition. We examine measurements with tissue substitute materials and theoretical HN for a broad range of tissues. Results are combined with parametric models for the x-ray linear attenuation coefficient ? and energy absorption coefficient ?en to predict values at energies 10 keV to 20 MeV. At photon energies employed for CT, the fractional contribution to ? from composition is 0.1-0.4 for soft tissues to bone respectively, and is responsible for strong correlations between HN and Ne. The atomic density of tissues excluding lung is near constant allowing the models to be re-expressed as a function of Ne alone. The transformed model is subjected to propagation of error analysis and results are presented as the ratio of uncertainties for ? or ?en to those for Ne. For soft tissues to bone the ratios are as follows: at photon energies 20-100 keV the ratio is 5.0-2.0, at intermediate energies it is unity and increases above 4 MeV to reach 1.5-2.0 at 20 MeV. Results are discussed in the context of attenuation correction and dosimetry calculations for the same range of photon energies.

  4. Structure determination from XAFS using high-accuracy measurements of x-ray mass attenuation coefficients of silver, 11 keV-28 keV, and development of an all-energies approach to local dynamical analysis of bond length, revealing variation of effective thermal contributions across the XAFS spectrum.

    PubMed

    Tantau, L J; Chantler, C T; Bourke, J D; Islam, M T; Payne, A T; Rae, N A; Tran, C Q

    2015-07-01

    We use the x-ray extended range technique (XERT) to experimentally determine the mass attenuation coefficient of silver in the x-ray energy range 11 kev-28 kev including the silver K absorption edge. The results are accurate to better than 0.1%, permitting critical tests of atomic and solid state theory. This is one of the most accurate demonstrations of cross-platform accuracy in synchrotron studies thus far. We derive the mass absorption coefficients and the imaginary component of the form factor over this range. We apply conventional XAFS analytic techniques, extended to include error propagation and uncertainty, yielding bond lengths accurate to approximately 0.24% and thermal Debye-Waller parameters accurate to 30%. We then introduce the FDMX technique for accurate analysis of such data across the full XAFS spectrum, built on full-potential theory, yielding a bond length accuracy of order 0.1% and the demonstration that a single Debye parameter is inadequate and inconsistent across the XAFS range. Two effective Debye-Waller parameters are determined: a high-energy value based on the highly-correlated motion of bonded atoms ([Formula: see text] Å), and an uncorrelated bulk value ([Formula: see text] Å) in good agreement with that derived from (room-temperature) crystallography. PMID:26075571

  5. Structure determination from XAFS using high-accuracy measurements of x-ray mass attenuation coefficients of silver, 11 keV–28 keV, and development of an all-energies approach to local dynamical analysis of bond length, revealing variation of effective thermal contributions across the XAFS spectrum

    NASA Astrophysics Data System (ADS)

    Tantau, L. J.; Chantler, C. T.; Bourke, J. D.; Islam, M. T.; Payne, A. T.; Rae, N. A.; Tran, C. Q.

    2015-07-01

    We use the x-ray extended range technique (XERT) to experimentally determine the mass attenuation coefficient of silver in the x-ray energy range 11 kev–28 kev including the silver K absorption edge. The results are accurate to better than 0.1%, permitting critical tests of atomic and solid state theory. This is one of the most accurate demonstrations of cross-platform accuracy in synchrotron studies thus far. We derive the mass absorption coefficients and the imaginary component of the form factor over this range. We apply conventional XAFS analytic techniques, extended to include error propagation and uncertainty, yielding bond lengths accurate to approximately 0.24% and thermal Debye–Waller parameters accurate to 30%. We then introduce the FDMX technique for accurate analysis of such data across the full XAFS spectrum, built on full-potential theory, yielding a bond length accuracy of order 0.1% and the demonstration that a single Debye parameter is inadequate and inconsistent across the XAFS range. Two effective Debye–Waller parameters are determined: a high-energy value based on the highly-correlated motion of bonded atoms ({?\\text{DW}}=0.1413(21) Å), and an uncorrelated bulk value ({?\\text{DW}}=0.1766(9) Å) in good agreement with that derived from (room-temperature) crystallography.

  6. Photoelectric cross sections for 72.1 - keV x rays in Al, Cu, Zr, Ag, Sn, Ta, Au, and Pb derived from a total attenuation-coefficient measurement

    Microsoft Academic Search

    Ramakrishna Gowda; B. Sanjeevaiah

    1974-01-01

    The photoelectric cross sections have been extracted from the total absorption cross sections. The total cross sections have been estimated by measuring the absorption in Al, Cu, Zr, Ag, Sn, Ta, Au, and Pb for 72.1-keV x rays resulting from the decay of 203Hg. The scattering cross sections are taken from recent tabulated values of Veigele for subtraction purposes. The

  7. Effects of the size of the X-ray beam in attenuation methods

    Microsoft Academic Search

    P F Judy; R M Witt

    1972-01-01

    X-ray attenuation methods to measure bone mineral mass and relative lean-fat composition of soft tissue utilize radionuclides as sources. The photon beam diameters are 1-3 mm to obtain adequate intensities for the activity of the sources used. Within these dimensions the bone mineral mass can change appreciably. To evaluate the effects of the finite size of the beam, the beam

  8. Research on reducing radiation exposure for clinical applications of X-ray attenuation

    NASA Astrophysics Data System (ADS)

    Jeon, Min-Cheol; Han, Man-Seok; So, Woon-Young; Lee, Hyeon-Guck; Kim, Yong-Kyun; Lee, Seung-Yeol

    2014-02-01

    This study was aimed at identifing areas with low radiation exposure where workers could be taken in the examination room in case that they had to hold the patients by estimating the attenuation of primary radiation and measuring the spatial distribution of scattered radiation. The laboratory equipment included on the X-ray generator, a phantom (human phantom), and a dosimeter. The experiment measured the performance of the examination system (dose reproducibility), the dose of primary radiation (X-rays), and the dose of scattered radiation (secondary radiation). Both the primary and the scattered radiation were attenuated by a factor of tube in vacuum experimental tests of the inverse square law. In this study, the attenuation was 2 ˜ 2.246 for primary radiation and 2 ˜ 2.105 for secondary radiation. Natural attenuation occurred as the X-rays passed through air, and an attenuation equation was established in this study. The equation for primary radiation (1st dose) was y = A1* exp(- x/t1)+ y0. The high-intensity contour of the direction for the cathode was wider than that of the direction for the anode, showing a wide range on the rear side of the cathode and on the rear side of the anode. We tried to find the positions where the workers' radiation exposure could be reduced. When the medical radiation workers have to hold the patient for an abdominal examination, they should be placed towards the tube anode and on the left side of the patient. For a lumbar-spine lateral examination, they should be placed towards the tube anode and behind the patient, and for a femur AP (anterior-posterior) examination, they should be placed towards the tube anode and on the right side of the patient.

  9. Experimental investigation of X-ray spectral absorption coefficients in heated Al and Ge on the Iskra-5 laser facility

    SciTech Connect

    Bondarenko, S V; Garanin, Sergey G; Zhidkov, N V; Pinegin, A V; Suslov, N A [Russian Federal Nuclear Center 'All-Russian Research Institute of Experimental Physics', Sarov, Nizhnii Novgorod region (Russian Federation)

    2012-01-31

    We set forth the data of experimental investigation of X-ray spectral absorption coefficients in the 1.1 - 1.6 keV photon energy range for Al and Ge specimens bulk heated by soft X-ray radiation. Two experimental techniques are described: with the use of one facility channel and the heating of specimens by the X-ray radiation from a plane burnthrough target, as well as with the use of four channels and the heating by the radiation from two cylindrical targets with internal input of laser radiation. The X-ray radiation absorption coefficients were studied by way of transmission absorption spectroscopy using backlighting X-ray radiation from a point source. The results of investigation of X-ray spectral absorption coefficients on the 1s - 2p transitions in Al atoms and the 2p - 3d transitions in Ge atoms are presented.

  10. X-ray attenuation cross sections for energies 100 eV to 100 keV and elements Z = 1 to Z = 92

    Microsoft Academic Search

    E. B. Saloman; J. H. Hubbell; J. H. Scofield

    1988-01-01

    This work presents for the energy range 0.1--100 keV the National Bureau of Standards (NBS) database of experimental x-ray attenuation coefficients (total absorption cross sections) and cross sections calculated using a relativistic Hartree--Slater model for the photoelectric cross section for all elements of atomic number Z = 1--92. The information is displayed in both tabular and graphical form. Also shown

  11. An empirical model of diagnostic x-ray attenuation under narrow-beam geometry

    SciTech Connect

    Mathieu, Kelsey B.; Kappadath, S. Cheenu; White, R. Allen; Atkinson, E. Neely; Cody, Dianna D. [Department of Bioengineering, Rice University, Houston, Texas 77005 (United States); Division of Diagnostic Imaging, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States); Division of Bioinformatics and Computational Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Statistics, Rice University, Houston, Texas 77005 (United States); Division of Diagnostic Imaging, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    2011-08-15

    Purpose: The purpose of this study was to develop and validate a mathematical model to describe narrow-beam attenuation of kilovoltage x-ray beams for the intended applications of half-value layer (HVL) and quarter-value layer (QVL) estimations, patient organ shielding, and computer modeling. Methods: An empirical model, which uses the Lambert W function and represents a generalized Lambert-Beer law, was developed. To validate this model, transmission of diagnostic energy x-ray beams was measured over a wide range of attenuator thicknesses [0.49-33.03 mm Al on a computed tomography (CT) scanner, 0.09-1.93 mm Al on two mammography systems, and 0.1-0.45 mm Cu and 0.49-14.87 mm Al using general radiography]. Exposure measurements were acquired under narrow-beam geometry using standard methods, including the appropriate ionization chamber, for each radiographic system. Nonlinear regression was used to find the best-fit curve of the proposed Lambert W model to each measured transmission versus attenuator thickness data set. In addition to validating the Lambert W model, we also assessed the performance of two-point Lambert W interpolation compared to traditional methods for estimating the HVL and QVL [i.e., semilogarithmic (exponential) and linear interpolation]. Results: The Lambert W model was validated for modeling attenuation versus attenuator thickness with respect to the data collected in this study (R{sup 2} > 0.99). Furthermore, Lambert W interpolation was more accurate and less sensitive to the choice of interpolation points used to estimate the HVL and/or QVL than the traditional methods of semilogarithmic and linear interpolation. Conclusions: The proposed Lambert W model accurately describes attenuation of both monoenergetic radiation and (kilovoltage) polyenergetic beams (under narrow-beam geometry).

  12. Evaluation of a ventricular assist device: stability under x-rays and therapeutic beam attenuation.

    PubMed

    Gossman, Michael S; Graham, Joel D; Tamez, Dan; Voskoboynikov, Neil; Larose, Jeffrey A

    2012-01-01

    Improved outcomes and quality of life of heart failure patients have been reported with the use of left ventricular assist devices (LVADs). However, little information exists regarding devices in patients undergoing radiation cancer treatment. Two HeartWare Ventricular Assist Device (HVAD) pumps were repeatedly irradiated with high intensity 18 MV x-rays to a dosage range of 64-75 Gy at a rate of 6 Gy/min from a radiation oncology particle accelerator to determine operational stability. Pump parameter data was collected through a data acquisition system. Second, a computerized tomography (CT) scan was taken of the device, and a treatment planning computer estimated characteristics of dose scattering and attenuation. Results were then compared with actual radiation measurements. The devices exhibited no changes in pump operation during the procedure, though the titanium components of the HVAD markedly attenuate the therapy beam. Computer modeling indicated an 11.8% dose change in the absorbed dosage that was distinctly less than the 84% dose change measured with detectors. Simulated and measured scattering processes were negligible. Computer modeling underestimates pretreatment dose to patients when the device is in the field of radiation. Future x-ray radiation dosimetry and treatment planning in HVAD patients should be carefully managed by radiation oncology specialists. PMID:22236626

  13. Resonant Raman scattering contribution to attenuation of x rays at energies in lower vicinity of the K-shell ionization threshold of some elements

    SciTech Connect

    Kumar, Sanjeev; Sharma, Veena; Kumar, Sunil; Alrakabi, Muhanad; Mehta, D.; Singh, Nirmal [Department of Physics, Panjab University, Chandigarh-160 014 (India)

    2009-05-15

    Attenuation of the x rays and gamma rays in the {sub 22}Ti, {sub 41}Nb, {sub 69}Tm, {sub 70}Yb, and {sub 71}Lu elements have been measured with special emphasis for the x ray energies (E{sub in}) in lower vicinity of the K shell ionization threshold (B{sub K}) of the element. The incident photon beam is obtained from decay of the {sup 55}Fe, {sup 241}Am, and {sup 57}Co radioisotopes, and fluorescence of the {sub 23}V, {sub 70}Yb, {sub 71}Lu, {sub 74}W, {sub 76}Os, and {sub 90}Th targets excited by the x rays and gamma rays from the radioisotopes. The measurements were performed using energy dispersive setups involving Ge detectors. The measured attenuation coefficients agree with the available theoretical values except at the photon energies with (B{sub K}-E{sub in}) less than or nearly equal to the K-shell width (GAMMA{sub K}), where significant positive deviations as large as factor of 2 have been observed. In view of reliability of the available theoretical cross sections for the photoionization and the photon scattering processes, the magnitude of positive alteration at the photon energy in lower vicinity of the ionization threshold is attributed to the K shell resonant Raman scattering (RRS) process and the corresponding cross sections have been deduced. Possible matrix effects in the energy dispersive x ray spectrometry due to RRS are also discussed.

  14. Numerical comparison of X-ray differential phase contrast and attenuation contrast

    PubMed Central

    Hahn, Dieter; Thibault, Pierre; Bech, Martin; Stockmar, Marco; Schleede, Simone; Zanette, Irene; Rack, Alexander; Weitkamp, Timm; Sztrókay, Aniko; Schlossbauer, Thomas; Bamberg, Fabian; Reiser, Maximilian; Pfeiffer, Franz

    2012-01-01

    We present a numerical tool to compare directly the contrast-to-noise-ratio (CNR) of the attenuation- and differential phase-contrast signals available from grating-based X-ray imaging for single radiographs. The attenuation projection is differentiated to bring it into a modality comparable to the differential phase projection using a Gaussian derivative filter. A Relative Contrast Gain (RCG) is then defined as the ratio of the CNR of image values in a region of interest (ROI) in the differential phase projection to the CNR of image values in the same ROI in the differential attenuation projection. We apply the method on experimental data of human breast tissue acquired using a grating interferometer to compare the two contrast modes for two regions of interest differing in the type of tissue. Our results indicate that the proposed method can be used as a local estimate of the spatial distribution of the ratio ?/?, i.e., real and imaginary part of the complex refractive index, across a sample. PMID:22741063

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

    DOEpatents

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

    2010-10-12

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

  16. Three-dimensional x-ray microtomography

    Microsoft Academic Search

    B. P. Flannery; H. W. Deckman; W. G. Roberge; K. L. DAmico

    1987-01-01

    The new technique of x-ray microtomography nondestructively generates three-dimensional maps of the x-ray attenuation coefficient inside small samples with approximately 1 percent accuracy and with resolution approaching 1 micrometer. Spatially resolved elemental maps can be produced with synchrotron x-ray sources by scanning samples at energies just above and below characteristic atomic absorption edges. The system consists of a high-resolution imaging

  17. X-ray attenuation of adipose breast tissue: in-vitro and in-vivo measurements using spectral imaging

    NASA Astrophysics Data System (ADS)

    Fredenberg, Erik; Erhard, Klaus; Berggren, Karl; Dance, David R.; Young, Kenneth C.; Cederström, Björn; Johansson, Henrik; Lundqvist, Mats; Moa, Elin; Homan, Hanno; Willsher, Paula; Kilburn-Toppin, Fleur; Wallis, Matthew

    2015-03-01

    The development of new x-ray imaging techniques often requires prior knowledge of tissue attenuation, but the sources of such information are sparse. We have measured the attenuation of adipose breast tissue using spectral imaging, in vitro and in vivo. For the in-vitro measurement, fixed samples of adipose breast tissue were imaged on a spectral mammography system, and the energy-dependent x-ray attenuation was measured in terms of equivalent thicknesses of aluminum and poly-methyl methacrylate (PMMA). For the in-vivo measurement, a similar procedure was applied on a number of spectral screening mammograms. The results of the two measurements agreed well and were consistent with published attenuation data and with measurements on tissue-equivalent material.

  18. The coefficient of bond thermal expansion measured by extended x-ray absorption fine structure

    NASA Astrophysics Data System (ADS)

    Fornasini, P.; Grisenti, R.

    2014-10-01

    The bond thermal expansion is in principle different from the lattice expansion and can be measured by correlation sensitive probes such as extended x-ray absorption fine structure (EXAFS) and diffuse scattering. The temperature dependence of the coefficient ?bond(T) of bond thermal expansion has been obtained from EXAFS for CdTe and for Cu. A coefficient ?tens(T) of negative expansion due to tension effects has been calculated from the comparison of bond and lattice expansions. Negative lattice expansion is present in temperature intervals where ?bond prevails over ?tens; this real-space approach is complementary but not equivalent to the Grüneisen theory. The relevance of taking into account the asymmetry of the nearest-neighbours distribution of distances in order to get reliable bond expansion values and the physical meaning of the third cumulant are thoroughly discussed.

  19. The Determination of the `Diffusion Coefficients' and the Stellar Wind Velocities for X-Ray Binaries

    E-print Network

    V. M. Lipunov; S. B. Popov

    1995-04-20

    The distribution of neutron stars (NS's) is determined by stationary solution of the Fokker-Planck equation. In this work using the observed period changes for four systems: Vela X-1, GX 301-2, Her X-1 and Cen X-3 we determined D, the 'diffusion coefficient',-parameter from the Fokker-Planck equation. Using strong dependence of D on the velocity for Vela X-1 and GX 301-2, systems accreting from a stellar wind, we determined the stellar wind velocity. For different assumptions for a turbulent velocity we obtained $V=(660-1440) km s ^{-1}$. It is in good agreement with the stellar wind velocity determined by other methods. We also determined the specific characteristic time scales for the 'diffusion processes' in X-ray pulsars. It is of order of 200 sec for wind-fed pulsars and 1000-10000 sec for the disk accreting systems.

  20. Attenuation coefficients for water quality trading.

    PubMed

    Keller, Arturo A; Chen, Xiaoli; Fox, Jessica; Fulda, Matt; Dorsey, Rebecca; Seapy, Briana; Glenday, Julia; Bray, Erin

    2014-06-17

    Water quality trading has been proposed as a cost-effective approach for reducing nutrient loads through credit generation from agricultural or point source reductions sold to buyers facing costly options. We present a systematic approach to determine attenuation coefficients and their uncertainty. Using a process-based model, we determine attenuation with safety margins at many watersheds for total nitrogen (TN) and total phosphorus (TP) loads as they transport from point of load reduction to the credit buyer. TN and TP in-stream attenuation generally increases with decreasing mean river flow; smaller rivers in the modeled region of the Ohio River Basin had TN attenuation factors per km, including safety margins, of 0.19-1.6%, medium rivers of 0.14-1.2%, large rivers of 0.13-1.1%, and very large rivers of 0.04-0.42%. Attenuation in ditches transporting nutrients from farms to receiving rivers is 0.4%/km for TN, while for TP attenuation in ditches can be up to 2%/km. A 95 percentile safety margin of 30-40% for TN and 6-10% for TP, applied to the attenuation per km factors, was determined from the in-stream sensitivity of load reductions to watershed model parameters. For perspective, over 50 km a 1% per km factor would result in 50% attenuation = 2:1 trading ratio. PMID:24866482

  1. Attenuation of Low-Energy Electrons by Solids: Results from X-Ray Photoelectron Spectroscopy

    Microsoft Academic Search

    R. G. Steinhardt; J. Hudis; M. L. Perlman

    1972-01-01

    The scattering half-thickness for electrons has been experimentally determined to be ~ 0.25 mug\\/cm2 (~ 13 Å carbon) for 1169-eV electrons and ~ 0.21 mug\\/cm2 (~ 10 Å carbon) for 920-eV electrons. The corresponding mass-scattering coefficients are 2.75 +\\/- 0.19 and 3.32+\\/-0.37 cm2\\/mug. Other useful and related attenuation parameters are defined and calculated. These results were obtained from measurements of

  2. X-ray microtomographic imaging and analysis for basic research

    Microsoft Academic Search

    J. H. Dunsmuir; S. Bennett; L. Fareria; A. Mingino; M. Sansone

    2006-01-01

    For research facilities with access to synchrotron x-ray sources, X-ray absorption microtomography (XMT) has evolved from an experimental imaging method to a specialized, if not yet routine, microscopy for imaging the 3D distribution of linear attenuation coefficients and, in some cases, elemental concentration with micron spatial resolution(1). Recent advances in source and detector design have produced conventional x-ray source instruments

  3. Determination of x-ray spectra from Al attenuation data by imposing a priori physical features of the spectrum: Theory and experimental validation

    SciTech Connect

    Delgado, Victor [Departamento de Radiologia, Universidad Complutense 28040 Madrid (Spain)

    2009-01-15

    The determination of the spectral distribution of an x-ray beam from attenuation measurements in a narrow beam is an ill-conditioned problem that has aroused great interest since it was first proposed by Silberstein in 1932. In this work, the explicit reconstruction of the spectral distribution directly from the attenuation curve, without differentiating it, is carried out by a maximum likelihood method that allows one to impose a priori physical features of an x-ray spectral distribution, such as the positiveness of the solution, the boundness of its support, and the position and shape of the spikes and edges associated with the characteristic radiation. The numerical simulations made and the experimental validation of the proposed method have shown that it is possible to reconstruct x-ray spectra that, having a realistic shape, accurately fit the attenuation curve and predict the energy fluence. Nevertheless, the reconstruction of spectra including the K x rays of W is less accurate than the reconstruction of spectra including L x rays of W or K x rays of Mo, even when a priori information about the position and shape of the spikes and edges associated with the characteristic radiation is used.

  4. Applications of simulated x-ray spectra to x-ray imaging

    NASA Astrophysics Data System (ADS)

    Elhila, H.; Mouze, D.

    1996-06-01

    When using microfocus x-ray sources for x-ray imaging (x-ray projection microscopy or microradiography), the measured intensities are influenced by the non-monochromaticity of the incident x-ray beam. This affects the transmitted signal in the image pixels and consequently brings about errors in quantitative measurements by x-ray absorption analysis or in tomographic reconstruction. A model developed to predict the spectral distribution of x-rays generated by electron bombardment on a metallic target has been modified to be adapted to transmission targets. It is used here, in combination with a semi-empirical analytical expression for mass attenuation coefficients, to calculate the overall energy transmitted to an x-ray imaging system and thus to simulate any x-ray projection experiment. In particular, spectral purity, which is a measure of the degree of monochromaticity, can be easily evaluated. In this paper simulations are used to evaluate the effect of each part of an imaging system on the spectral purity. Here we are concerned with the effect of target and/or filter thicknesses and the influence on the purity of the selective absorption efficiency of phosphor screens with x-ray energy. As an example, three targets and two kinds of phosphor screen widely in use in x-ray CCD cameras have been considered.

  5. Data weighted vs. non-data weighted dual energy reconstructions for X-ray tomography

    Microsoft Academic Search

    P. Sukovic; N. H. Clinthorne

    1998-01-01

    X-ray transmission tomography is useful for estimation of attenuation correction for simultaneously obtained emission tomography images. Moreover, X-ray attenuation coefficients can be combined with emission measurements in order to create combined anatomical-functional images. It is imperative, then, that as low X-ray dosage as possible be used. At those fluxes implementation of iterative algorithms becomes desirable. However, that was not the

  6. Relating x-ray attenuation measurements to water content and distribution in SB-15D core

    SciTech Connect

    Bonner, B.P.; Roberts, J.J.; Schneberk, D.J

    1996-09-30

    Making improved estimates of the water content of The Geysers reservoir is fundamental to efficient and economic long term production of steam power from the resource. A series of coordinated physical properties measurements form core recovered from the SB-15D, reported in this volume in a series of papers, have been made to better understand water storage and to relate water content and distribution to observable geophysical properties such as electrical conductivity and seismic velocities. A principal objective here is to report new interpretations of x-ray scans made within 72 hours of core recovery from SB-15D, which suggest, taking advantage of preliminary measurements of capillary suction for metagraywacke, that water content was low in much of the preserved core.

  7. Application of CdTe photon-counting x-ray imager to material discriminated x-ray CT

    NASA Astrophysics Data System (ADS)

    Nakashima, Takuya; Morii, Hisashi; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

    2007-09-01

    We proposed that material discriminated X-ray CT with conventional X-ray tube and energy differentiation type 64ch CdTe radiation line sensor. Distribution of Atomic number was obtained by using dual-energy X-ray CT. In this study, problem of conventional X-ray tube was reduced by the collimator and measurement time. So line attenuation coefficient was obtained depend on theory. Atomic number was calculated with two different methods. We could obtain atomic number within about three error margin.

  8. Physics of contrast mechanism and averaging effect of linear attenuation coefficients in a computerized transverse axial tomography CTAT) transmission scanner.

    PubMed

    Tsai, C M; Cho, Z H

    1976-07-01

    Detailed studies of the basic contrast mechanisms in computerized transverse axial tomography scanners have been carried out. Contrast is related to the effective atomic numbers and electron densities of materials and the resultant linear attenuation coefficients. We have therefore quantitatively evaluated various samples defined by these parameters. A multienergetic X-ray source causes resolution degrading problems arising from the averaging effect of the linear attenuation coefficients. The controversy regarding the use of fixed length water bath as a reference to compensate the spectral shift (hardening) effect of the multienergetic X-ray source is also analysed and reported. Computer simulations demonstrating the sensitivities of the linear attenuation coefficient measurements and errors, as functions of the energy spectrum, were made for representative cases. Simulation results indicate that by using a full water bath, artifacts stemming from the multienergetic X-ray souce can be significantly reduced. An alternative approach using a count rate equalizer, considered to be another way of reducing the wide dynamic range in count rate when a water bath is not used, is also studied and the results reported. PMID:972920

  9. Dual energy CT-based characterization of x-ray attenuation properties of breast equivalent material plates

    NASA Astrophysics Data System (ADS)

    Geeraert, N.; Klausz, R.; Giudici, P.; Muller, S.; Cockmartin, L.; Bosmans, H.

    2012-03-01

    Breast density is more and more considered as an important risk factor for breast cancer and several quantitative breast density evaluation methods have been proposed. The reference material for simulation of the breast attenuation properties of glandular and adipose breast tissues is manufactured by a single provider. In order to characterize the attenuation properties of these materials, measurements in Hounsfield Units (HU) have been performed using a CT-scanner. Breastequivalent plates have been imaged in different configurations (plates in and orthogonal to image planes), providing consistent results (+/- 1.3 HU). Breast density equivalent plates of different nominal breast density equivalences and sizes were measured, demonstrating both a good homogeneity within the plates (+/- 1.8 HU) and a good consistency between plates of the same nominal breast density equivalence (+/- 1.5 HU). In addition, dual energy CT provided mono-energetic HU from which mono-energetic linear attenuation coefficients of water and glandular and adipose equivalent materials were computed. The values for these coefficients were found in good agreement with results from literature, respectively direct mono-energetic measurements of breast samples, and computation by combining published breast tissue atomic compositions and linear attenuation coefficient tables. In conclusion, CT was found effective for the verification of the breast equivalent material, and the homogeneity and consistency of the plates were found satisfactory. Furthermore, the most recent spectral CT technology allowed demonstrating a good agreement of the attenuation properties of breastequivalent material plates with state-of-the-art knowledge of real breast tissue attenuation.

  10. SIM.RI(I)-K3 comparison of calibration coefficients at radiotherapy level for orthovoltage x-ray beams

    NASA Astrophysics Data System (ADS)

    O'Brien, M.; McCaffrey, J.; Shen, H.; Saraví, M.; Stefanic, A.; Montaño Ortiz, G.; Carlos, M.; da Silva, C.; Álvarez, J.; Tovar, V.

    2015-01-01

    Air-kerma calibration coefficients were compared at the radiotherapy level for orthovoltage x ray beams in the SIM.RI(I)-K3 comparison for members of the Sistema Interamericano de Metrología (SIM). Five SIM laboratories participated in the comparison: NIST, NRC, ININ, CNEA and LNMRI, the NIST being the pilot laboratory. Results from the comparison are linked to the BIPM.RI(I)-K3 key comparison reference value through the NIST-BIPM comparison made in 2003 and will meet requirements of the Mutual Recognition Arrangement (MRA) to support several CMCs (calibration and measurement capability claims) of the participants. The comparison began in October of 2007 and the measurements were completed in September 2008. The results reveal the degree to which the participating calibration facility can demonstrate proficiency in transferring air-kerma calibrations under the conditions of the said facility at the time of the measurements. The evaluation of the degrees of equivalence was performed as described in the comparison protocol. The comparison of the calibration coefficients for the four chambers is based on the average ratios of the calibration coefficients measured at the NIST and at each participating laboratory. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Dose reduction technique using a combination of a region of interest (ROI) material x-ray attenuator and spatially different temporal filtering for fluoroscopic interventions

    NASA Astrophysics Data System (ADS)

    Swetadri Vasan, S. N.; Panse, A.; Jain, A.; Sharma, P.; Ionita, Ciprian N.; Titus, A. H.; Cartwright, A. N.; Bednarek, D. R.; Rudin, S.

    2012-03-01

    We demonstrate a novel approach for achieving patient dose savings during image-guided neurovascular interventions, involving a combination of a material x-ray region of interest (ROI) attenuator and a spatially different ROI temporal filtering technique. The part of the image under the attenuator is reduced in dose but noisy and less bright due to fewer x-ray quanta reaching the detector, as compared to the non-attenuating (or less attenuating) region. First the brightness is equalized throughout the image by post processing and then a temporal filter with higher weights is applied to the high attenuating region to reduce the noise, at the cost of increased lag; however, in the regions where less attenuation is present, a lower temporal weight is needed and is applied to preserve temporal resolution. A simulation of the technique is first presented on an actual image sequence obtained from an endovascular image guided interventional (EIGI) procedure. Then the actual implementation of the technique with a physical ROI attenuator is presented. Quantitative analysis including noise analysis and integral dose calculations are presented to validate the proposed technique.

  12. Direct determination of the attenuation coefficient for radionuclide volume measurements

    Microsoft Academic Search

    A. M. Keller; T. R. Simon; T. C. Smitherman; C. R. Malloy; G. J. Dehmer

    1987-01-01

    Correcting for the attenuation of photons between the cardiac chambers and chest surface is crucial for accurate nongeometric ventricular volume determinations from equilibrium radionuclide angiograms. Previous techniques have assumed that the attenuation coefficient of water for \\/sup 99m\\/Tc (0.15\\/cm) should be used for this correction. In this study, this assumption was tested directly by measuring attenuation of the activity of

  13. FREQUENCY DEPENDENT ULTRASONIC ATTENUATION COEFFICIENT ASSESSMENT IN FRESH

    E-print Network

    Illinois at Urbana-Champaign, University of

    = = where is the average acoustic energy density, I is the acoustic intensity and cois procedures for measuring total acoustic power typically measure the force via a balance apparatus using a phase insensitive, radiation force balance technique. Ultrasonic attenuation coefficient

  14. Measurements of spectral attenuation coefficients in the lower Chesapeake Bay

    NASA Technical Reports Server (NTRS)

    Houghton, W. M.

    1983-01-01

    The spectral transmission was measured for water samples taken in the lower Chesapeake Bay to allow characterization of several optical properties. The coefficients of total attenuation, particle attenuation, and absorption by dissolved organic matter were determined over a wavelength range from 3500 A to 8000 A. The data were taken over a 3 year period and at a number of sites so that an indication of spatial and temporal variations could be obtained. The attenuations determined in this work are, on the average, 10 times greater than those obtained by Hulburt in 1944, which are commonly accepted in the literature for Chesapeake Bay attenuation.

  15. Limited Data X-Ray Tomography Using Nonlinear Evolution Equations

    Microsoft Academic Search

    Ville Kolehmainen; Matti Lassas; Samuli Siltanen

    2008-01-01

    A novel approach to the X-ray tomography problem with sparse projection data is proposed. Non-negativity of the X-ray attenuation coefficient is enforced by modelling it as max{?(x), 0} where ? is a smooth function. The function ? is computed as the equilibrium so- lution of a nonlinear evolution equation analogous to the equations used in level set methods. The reconstruction

  16. Initial study of quasi-monochromatic X-ray beam performance for X-ray computed mammotomography

    Microsoft Academic Search

    Randolph L. McKinley; Martin P. Tornai; Ehsan Samei; Marques L. Bradshaw

    2005-01-01

    We evaluate the feasibility, benefits, and operating parameters of a quasimonochromatic beam for a newly developed x-ray cone beam computed mammotomography application. The value of a near monochromatic x-ray source for fully 3D dedicated mammotomography is the expected improved ability to separate tissues with very small differences in attenuation coefficients while maintaining dose levels at or below that of existing

  17. X-ray attenuation measurements in a cavitating mixing layer for instantaneous two-dimensional void ratio determination

    SciTech Connect

    Aeschlimann, Vincent; Barre, Stephane [LEGI, Grenoble-INP, CNRS BP 53, 38041 Grenoble (France); Legoupil, Samuel [Commissariat a l'Energie Atomique (CEA), CEA-Saclay, DRT/LIST, 91191 Gif sur Yvette (France)

    2011-05-15

    The purpose of this experimental study was to analyze a two-dimensional cavitating shear layer. The global aim of this work was to obtain a better understanding and modeling of cavitation phenomenon in a 2D turbulent sheared flow which can be considered as quite representative of cavitating rocket engine turbopomp inducers. This 2D mixing layer flow provided us a well documented test case which can be used for the characterization of the cavitation effects in sheared flows. The development of a velocity gradient was observed inside a liquid water flow: Kelvin-Helmholtz instabilities developed at the interface. Vaporizations and implosions of cavitating structures inside the vortices were observed. X-ray attenuation measurements were performed to estimate the amount of vapor present inside the mixing area. Instantaneous two-dimensional void ratio fields were acquired. The real spatial resolutions are 0.5 mm with 2000 fps and 1.5 mm with 20 000 fps. The effective time resolution is equal to the camera frame rate up to a 19% void ratio variation between two consecutive images. This seems to be sufficient in the context of the present flow configuration. The two-phase structures present inside the mixing area were analyzed at three different cavitation levels and their behaviors were compared to non-cavitating flow dynamic. Convection velocities and vortices shedding frequencies were estimated. Results show that vapor was transported by the turbulent velocity field. Statistical analysis of the void ratio signal was carried out up to the fourth order moment. This study provided a global understanding of the cavitating structure evolution and of the cavitation effects on turbulent sheared flows.

  18. Direct determination of the attenuation coefficient for radionuclide volume measurements

    SciTech Connect

    Keller, A.M.; Simon, T.R.; Smitherman, T.C.; Malloy, C.R.; Dehmer, G.J.

    1987-01-01

    Correcting for the attenuation of photons between the cardiac chambers and chest surface is crucial for accurate nongeometric ventricular volume determinations from equilibrium radionuclide angiograms. Previous techniques have assumed that the attenuation coefficient of water for /sup 99m/Tc (0.15/cm) should be used for this correction. In this study, this assumption was tested directly by measuring attenuation of the activity of a radioactive source within the right and left cardiac chambers. The balloon of a flow-directed catheter, filled with /sup 99m/Tc, was used as a source and its depth within the body was measured with biplane fluoroscopy. In ten patients, a total of 36 measurements of attenuation were made. With linear regression analysis, the overall calculated attenuation coefficient, mu, was 0.12/cm (standard error of slope = 0.01, R = 0.93). Although the mean value of mu varied from 0.08 to 0.13 for four different intracardiac locations these differences were not significant. These direct measurements indicate that the attenuation of photons in the heart is not equivalent to that of water and suggest that an attenuation coefficient of 0.12/cm should be used in analyzing ventricular activity.

  19. Direct determination of the attenuation coefficient for radionuclide volume measurements.

    PubMed

    Keller, A M; Simon, T R; Smitherman, T C; Malloy, C R; Dehmer, G J

    1987-01-01

    Correcting for the attenuation of photons between the cardiac chambers and chest surface is crucial for accurate nongeometric ventricular volume determinations from equilibrium radionuclide angiograms. Previous techniques have assumed that the attenuation coefficient of water for 99mTc (0.15/cm) should be used for this correction. In this study, this assumption was tested directly by measuring attenuation of the activity of a radioactive source within the right and left cardiac chambers. The balloon of a flow-directed catheter, filled with 99mTc, was used as a source and its depth within the body was measured with biplane fluoroscopy. In ten patients, a total of 36 measurements of attenuation were made. With linear regression analysis, the overall calculated attenuation coefficient, mu, was 0.12/cm (standard error of slope = 0.01, R = 0.93). Although the mean value of mu varied from 0.08 to 0.13 for four different intracardiac locations these differences were not significant. These direct measurements indicate that the attenuation of photons in the heart is not equivalent to that of water and suggest that an attenuation coefficient of 0.12/cm should be used in analyzing ventricular activity. PMID:3794802

  20. Fiber Attenuation To measure the attenuation coefficient of a multi-mode fiber, and to

    E-print Network

    Collins, Gary S.

    Fiber Attenuation Purpose: To measure the attenuation coefficient of a multi-mode fiber, and to see the effect of mode scrambling on the fiber output. Equipment: · optics table, or 2'x2' breadboard · 4 1 -20 (340C) · short rod For the fiber- · F-MLD-500 fiber (~500 meters) · fiber coupler · 20X objective lens

  1. Hygrothermal degradation of 3-glycidoxypropyltrimethoxysilane films studied by neutron and X-ray reflectivity and attenuated total reflection infrared spectroscopy.

    SciTech Connect

    Tallant, David Robert; Garcia, Manuel Joseph; Majewski, Jaroslaw (Los Alamos National Lab, Los Alamos, NM); Kent, Michael Stuart; Yim, Hyun

    2005-05-01

    Thin films of organosilanes have great technological importance in the areas of adhesion promotion, durability, and corrosion resistance. However, it is well-known that water can degrade organosilane films, particularly at elevated temperatures. In this work, X-ray and neutron reflectivity (XR and NR) were combined with attenuated total reflection infrared (ATR-IR) spectroscopy to study the chemical and structural changes within thin films of (3-glycidoxypropyl)trimethoxysilane (GPS) after exposure for various periods of time to air saturated with either D{sub 2}O or H{sub 2}O at 80 C. For NR and XR, ultrathin ({approx}100 {angstrom}) films were prepared by spin-coating. Both D{sub 2}O and H{sub 2}O provide neutron scattering contrast with GPS. Variations in the neutron scattering length density (SLD) profiles (a function of mass density and atomic composition) with conditioning time were measured after drying the samples out and also swelled with H{sub 2}O or D{sub 2}O vapor at room temperature. For samples that were dried out prior to measurement, little or no change was observed for H{sub 2}O conditioning up to 3.5 days, but large changes were observed after 30 days of conditioning. The range of conditioning time for this structural change was narrowed to between 4 and 10 days with XR. The SLD profiles indicated that the top portion of the GPS film was transformed into a thick low-density layer after conditioning, but the bottom portion showed little structural change. A previous NR study of as-prepared GPS films involving swelling with deuterated nitrobenzene showed that the central portion of the film has much lower cross-link density than the region nearest the substrate. The present data show that the central portion also swells to a much greater extent with water and hydrolyzes more rapidly. The chemical degradation mechanism was identified by IR as hydrolysis of siloxane bonds. For ATR-IR, GPS films were prepared by dip-coating, which resulted in a greater and more variable thickness than for the spin-coated samples. The IR spectra revealed an increase in vicinal silanol generation over the first 3 days of conditioning followed by geminal silanol generation. Thus, the structural change detected by NR and XR roughly coincided with the onset of geminal silanol generation. Finally, little change in the reflectivity data was observed for films conditioned with D{sub 2}O at 80 C for 1 month. This indicates that hydrolysis of Si-O-Si is much slower with D{sub 2}O than with H{sub 2}O.

  2. Determination of mass attenuation coefficients for threshold contrast evaluation in digital mammography

    NASA Astrophysics Data System (ADS)

    Hummel, Johann; Semturs, Friedrich; Menhart, Susanne; Figl, Michael

    2010-04-01

    According to the 'European protocol for the quality control of the physical and technical aspects of mammography screening' (EPQC) image quality digital mammography units has to be evaluated at different breast thicknesses. At the standard thickness of 50 mm polymethyl methacrylate (PMMA) image quality is determined by the analysis of CDMAM contrast detail phantom images where threshold contrasts are calculated for different gold disc diameters. To extend these results to other breast thicknesses contrast-to-noise ratios (CNR) and threshold contrast (TC) visibilities have to be calculated for all required thicknesses. To calculate the latter the mass attenuation coefficient (MAC) of gold has to be known for all possible beam qualities in the tube voltage range between 26 and 32 kV. In this paper we first determined the threshold contrast visibility using the CDMAM phantom with the same beam quality at different current-time products (mAs). We can derive from Rose theory that CNR • CT • ? = const, where ? is the diameter of the gold cylinder. From this the corresponding attenuation coefficients can be calculated. This procedure was repeated for four different beam qualities (Mo/Mo 27kV, Rh/Rh 29kV, Rh/Rh 31 kV, and W/Rh 29 kV)). Next, we measured the aluminium half value layer (HVL) of all x-ray spectra relevant for mammography. Using a first order Taylor expansion of MAC as a function of HVL, all other desired MAC can be calculated. The MAC as a function of the HVL was derived to MAChvl = -286.97 * hvl+186.03 with R2 = 0.997, where MAChvl indicates the MAC for all specific x-ray spectrum defined by its aluminium half value layer. Based on this function all necessary MACs needed for quality assurance (QA) were calculated. The results were in good agreement with the data found in the protocol.

  3. Studies on effective atomic numbers, electron densities from mass attenuation coefficients near the K edge in some samarium compounds.

    PubMed

    Akman, F; Durak, R; Turhan, M F; Kaçal, M R

    2015-07-01

    The effective atomic numbers and electron densities of some samarium compounds were determined using the experimental total mass attenuation coefficient values near the K edge in the X-ray energy range from 36.847 up to 57.142keV. The measurements, in the region from 36.847 to 57.142keV, were done in a transmission geometry utilizing the K?2, K?1, K?1 and K?2 X-rays from different secondary source targets excited by the 59.54keV gamma-photons from an Am-241 annular source. This paper presents the first measurement of the effective atomic numbers and electron densities for some samarium compounds near the K edge. The results of the study showed that the measured values were in good agreement with the theoretically calculated ones. PMID:25880612

  4. Determination of Mass Attenuation Coefficients for CuInSe2 and CuGaSe2 Semiconductors

    SciTech Connect

    Celik, Ahmet; Cevik, Ugur; Baltas, Hasan; Bacaksiz, Emin [Department of Physics, Faculty of Arts and Sciences, Karadeniz Technical University, 61080 Trabzon (Turkey)

    2007-04-23

    This work presents mass attenuation coefficients values of CuInSe2 and CuGaSe2 semiconductor thin films commonly used in photovoltaic devices. The mass attenuation coefficients were measured at different energies from 11.9 to 37.3 keV by using the secondary excitation method. Monochromatic photons were obtained using the Br, Sr, Mo, Cd, Te, Ba and Nd secondary targets. 59.5 keV gamma rays emitted from an annular Am-241 radioactive source were used to excite secondary targets. Characteristic X-rays emitted from secondary target were counted by a Si(Li) detector with a resolution of 0.16 keV at 5.9 keV. The measured values were compared with theoretical values calculated using WinXCOM program.

  5. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    ERIC Educational Resources Information Center

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  6. X-ray tube voltage and image quality in adult and pediatric CT

    NASA Astrophysics Data System (ADS)

    Huda, W.; Ogden, K. M.; Scalzetti, E. M.; Lavallee, R. L.; Samei, E.

    2006-03-01

    The purpose of this study was to investigate how tissue x-ray attenuation coefficients, and their uncertainties, vary with x-ray tube voltage in different sized patients. Anthropomorphic phantoms (newborn, 10 year old, adult) were scanned a GE LightSpeed scanner at four x-ray tube voltages. Measurements were made of tissue attenuation in the head, chest and abdomen regions, as well as the corresponding noise values. Tissue signal to noise ratios (SNR) were obtained by dividing the average attenuation coefficient by the corresponding standard deviation. Soft tissue attenuation coefficients, relative to water, showed little variation with patient location or x-ray voltage (< 0.5%), but increasing the x-ray tube voltage from 80 to 140 kV reduced bone x-ray attenuation by ~14%. All tissues except adult bone showed a reduction of noise with increasing x-ray tube voltage (kV); the noise was found to be proportional to kV n and the average value of n for all tissues was -1.19 +/- 0.57. In pediatric patients at a constant x-ray tube voltage, SNR values were approximately independent of the body region, but the adult abdomen soft tissue SNR values were ~40% lower than the adult head. SNR values in the newborn were more than double the corresponding SNR soft tissue values in adults. SNR values for lung and bone were generally lower than those for soft tissues. For soft tissues, increasing the x-ray tube voltage from 80 to 140 kV increased the SNR by an average of ~90%. Data in this paper can be used to help design CT imaging protocols that take into account patient size and diagnostic imaging task.

  7. A High Temperature Precision X-Ray Camera: Some Measurements of the Thermal Coefficients of Expansion of Beryllium

    Microsoft Academic Search

    Paul Gordon

    1949-01-01

    A high temperature precision x-ray camera has been designed and constructed by modification of the familiar back-reflection symmetrical focusing type of camera. The camera, specimen, and furnace are used within a vacuum chamber to avoid oxidation. The apparatus in its present form has been employed at temperatures up to 1000°C, but higher temperatures could be easily attained by making a

  8. Quantitative Mass Density Image Reconstructed from the Complex X-Ray Refractive Index

    PubMed Central

    Mukaide, Taihei; Iida, Atsuo; Watanabe, Masatoshi; Takada, Kazuhiro; Noma, Takashi

    2015-01-01

    We demonstrate a new analytical X-ray computed tomography technique for visualizing and quantifying the mass density of materials comprised of low atomic number elements with unknown atomic ratios. The mass density was obtained from the experimentally observed ratio of the imaginary and real parts of the complex X-ray refractive index. An empirical linear relationship between the X-ray mass attenuation coefficient of the materials and X-ray energy was found for X-ray energies between 8 keV and 30 keV. The mass density image of two polymer fibers was quantified using the proposed technique using a scanning-type X-ray microbeam computed tomography system equipped with a wedge absorber. The reconstructed mass density agrees well with the calculated one. PMID:26114770

  9. X-ray transmissive debris shield

    DOEpatents

    Spielman, R.B.

    1996-05-21

    An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

  10. X-ray transmissive debris shield

    DOEpatents

    Spielman, Rick B. (Albuquerque, NM)

    1996-01-01

    An X-ray debris shield for use in X-ray lithography that is comprised of an X-ray window having a layer of low density foam exhibits increased longevity without a substantial increase in exposure time. The low density foam layer serves to absorb the debris emitted from the X-ray source and attenuate the shock to the window so as to reduce the chance of breakage. Because the foam is low density, the X-rays are hardly attenuated by the foam and thus the exposure time is not substantially increased.

  11. X-Ray Data Booklet

    NSDL National Science Digital Library

    Attwood, David.

    2000-01-01

    The X-Ray Data Booklet is provided by the Center for X-ray Optics and Advanced Light Source of the Lawrence Berkeley National Laboratory, which is funded by the US Department of Energy. The online publication contains topics such as x-ray properties of elements, mass absorption coefficients, synchrotron radiation, scattering processes, low-energy electron ranges in matter, optics and detectors, specular reflectivities for grazing-incidence mirrors, and other practical information that has been produced and gathered as a result of research at the center. Additional features of the informative site include an interactive periodic table of X-Ray properties and free deliverable hardcopies of the document.

  12. X-Ray Spectroscopy of Gold Nanoparticles

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana N.; Montenegro, M.; Pradhan, A. K.; Pitzer, R.

    2009-06-01

    Inner shell transitions, such as 1s-2p, in heavy elements can absorb or produce hard X-rays, and hence are widely used in nanoparticles. Bio-medical research for cancer treatment has been using heavy element nanoparticles, embeded in malignant tumor, for efficient absorption of irradiated X-rays and leading emission of hard X-rays and energetic electrons to kill the surrounding cells. Ejection of a 1s electron during ionization of the element by absorption of a X-ray photon initiates the Auger cascades of emission of photons and electrons. We have investigated gold nanoparticles for the optimal energy range, below the K-edge (1s) ionization threshold, that corresponds to resonant absorption of X-rays with large attenuation coefficients, orders of magnitude higher over the background as well as to that at K-edge threshold. We applied these attenuation coefficients in Monte Carlo simulation to study the intensities of emission of photons and electrons by Auger cascades. The numerical experiments were carried out in a phantom of water cube with a thin layer, 0.1mm/g, of gold nanoparticles 10 cm inside from the surface using the well-known code Geant4. We will present results on photon and electron emission spectra from passing monochromatic X-ray beams at 67 keV, which is the resonant energy for resonant K_{?} lines, at 82 keV, the K-shell ionization threshold, and at 2 MeV where the resonant effect is non-existent. Our findings show a high peak in the gold nanoparticle absorption curve indicating complete absorption of radiation within the gold layer. The photon and electron emission spectra show resonant features. Acknowledgement: Partially supported by a Large Interdisciplinary Grant award of the Ohio State University and NASA APRA program (SNN). The computational work was carried out on the Cray X1 and Itanium 4 cluster at the Ohio Supercomputer Center, Columbus Ohio. "Resonant X-ray Irradiation of High-Z Nanoparticles For Cancer Theranostics" (refereed presentation), A Pradhan, S Nahar, M Montenegro, C Sur, M Mrozik, R Pitzer, E Silver, Y Yu, 50th Annual Meeting of the American Association of Physicists in Medicine in Houston, Texas, July 27 - 31, 2008

  13. Measurement of Acoustic Attenuation and Absorption Coefficients using Thermometry

    NASA Astrophysics Data System (ADS)

    Morris, Hugh; Rivens, Ian; Shaw, Adam; ter Haar, Gail

    2007-05-01

    Accurate knowledge of both the attenuation and the absorption coefficient of tissue are required when planning an optimal high intensity focused ultrasound treatment. A novel technique for simple measurement of this parameters has been developed in which a thin-film thermocouple (TFT) is placed between two layers of tissue of different thicknesses. The sample can be rotated about an axis through the junction of the TFT so that it can be insonated from either side leaving the tissue adjacent to the junction unchanged, but changing the overlying thickness. The attenuation and absorption coefficients can be calculated from the heating curves measured in the two orientations. Experiments have been carried out in both tissue mimicking material (TMM) and in ex vivo liver tissue. Weakly focused transducers, resonant at 1.05 MHz, 2.4 MHz and 3.55 MHz were used at free-field spatial peak intensities of 9-14 W/cm2. The temperature rise was measured as a function of time using a TFT. These thermocouples are not subject to the viscous heating artefact that is common to other thermocouple devices and so are advantageous for this purpose. Alignment was achieved with a 3D automated gantry system, which was controlled with specialised software. Timing and data acquisition were also controlled with this software. All experiments were carried out in degassed water. Results for TMM and degassed excised bovine liver are presented.

  14. Measurements of the hard-x-ray reflectivity of iridium

    SciTech Connect

    Romaine, S.; Bruni, R.; Gorenstein, P.; Zhong, Z

    2007-01-10

    In connection with the design of a hard-x-ray telescope for the Constellation X-Ray Observatory we measured the reflectivity of an iridium-coated zerodur substrate as a function of angle at 55, 60, 70, and 80 keV at the National Synchrotron Light Source of Brookhaven National Laboratory. The optical constants were derived from the reflectivity data. The real component of the index of refraction is in excellent agreement with theoretical values at all four energies. However, the imaginary component, which is related to the mass attenuation coefficient, is 50% to 70% larger at 55, 60, and 70 keV than theoretical values.

  15. Infrared Radiography: Modeling X-ray Imaging Without Harmful Radiation

    NASA Astrophysics Data System (ADS)

    Zietz, Otto; Mylott, Elliot; Widenhorn, Ralf

    2015-01-01

    Planar x-ray imaging is a ubiquitous diagnostic tool and is routinely performed to diagnose conditions as varied as bone fractures and pneumonia. The underlying principle is that the varying attenuation coefficients of air, water, tissue, bone, or metal implants within the body result in non-uniform transmission of x-ray radiation. Through the detection of transmitted radiation, the spatial organization and composition of materials in the body can be ascertained. In this paper, we describe an original apparatus that teaches these concepts by utilizing near infrared radiation and an up-converting phosphorescent screen to safely probe the contents of an opaque enclosure.

  16. Quantitative 3D petrography using x-ray tomography: Application to Bishop Tuff pumice clasts

    Microsoft Academic Search

    Guilherme A. R. Gualda; Mark Rivers

    2006-01-01

    Textures are traditionally studied using the petrographic microscope, which limits observations to 2D sections of 3D objects. Given the difficulty in retrieving information on shapes, sizes and spatial distribution of objects in 3D from random sections, a method that can yield observations in 3D is highly desirable.X-ray tomography yields a 3D map of the linear X-ray attenuation coefficient, which is

  17. Computed Tomography with an X-Ray Transmission Pencil Beam Scanner

    Microsoft Academic Search

    George X. Kambic; Robert H. Wake

    1977-01-01

    The pencil beam x-ray transmission computed tomographic (CT) scanner was the first type of scanner to be applied to radiologic medicine. It utilizes a rotate and traverse scanning mechanism. The scanner provides 2 dimensional images of a cross-section of the human body and relates an arbitrary CT number scale to the linear x-ray attenuation coefficient. The scanner can discriminate small

  18. Author's personal copy Assessment of satellite-derived diffuse attenuation coefficients and euphotic depths

    E-print Network

    Meyers, Steven D.

    sensing MODIS SeaWiFS Bio-optical algorithm Diffuse attenuation coefficient Euphotic depth Optical data to MODIS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. The products included the diffuse attenuAuthor's personal copy Assessment of satellite-derived diffuse attenuation coefficients

  19. Material Identification from X-ray Images Made by Energy-Differentiation Type X-ray Line Sensor

    Microsoft Academic Search

    Masao Matsumoto; Naoki Takayama

    \\u000a It was confirmed that linear attenuation coefficient and effective atomic number of objects could be identified by X-ray 2D\\u000a and CT images discriminated by different energy. The differences between theoretical and experimental values of linear attenuation\\u000a coefficient of each object from Xray images were 0.01-22.6% for carbon, 0.01%-23.1% for acrylic resin, and 0.07-22.1% for\\u000a aluminum. The effective atomic number of

  20. Representative Elementary Length to Measure Soil Mass Attenuation Coefficient

    PubMed Central

    Borges, J. A. R.; Pires, L. F.; Costa, J. C.

    2014-01-01

    With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (?s) is an important parameter for CT and GAT analysis. When experimentally determined (?es), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils for ?es measurements. Two radioactive sources were employed (241Am and 137Cs), three collimators (2–4?mm diameters), and 14 thickness (x) samples (2–15?cm). Results indicated ideal thickness intervals of 12–15 and 2–4?cm for the sources 137Cs and 241Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated that ?es average values obtained for x?>?4?cm and source 241Am might induce to the use of samples which are not large enough for soil bulk density evaluations (?s). As a consequence, ?s might be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study. PMID:24672338

  1. Representative elementary length to measure soil mass attenuation coefficient.

    PubMed

    Borges, J A R; Pires, L F; Costa, J C

    2014-01-01

    With increasing demand for better yield in agricultural areas, soil physical property representative measurements are more and more essential. Nuclear techniques such as computerized tomography (CT) and gamma-ray attenuation (GAT) have been widely employed with this purpose. The soil mass attenuation coefficient (?(s)) is an important parameter for CT and GAT analysis. When experimentally determined (?(es)), the use of suitable sized samples enable to evaluate it precisely, as well as to reduce measurement time and costs. This study investigated the representative elementary length (REL) of sandy and clayey soils for ?(es) measurements. Two radioactive sources were employed ((241)Am and (137)Cs), three collimators (2-4 mm diameters), and 14 thickness (x) samples (2-15 cm). Results indicated ideal thickness intervals of 12-15 and 2-4 cm for the sources (137)Cs and (241)Am, respectively. The application of such results in representative elementary area (REA) evaluations in clayey soil clods via CT indicated that ?(es) average values obtained for x > 4 cm and source (241)Am might induce to the use of samples which are not large enough for soil bulk density evaluations (?(s)). As a consequence, ?(s) might be under- or overestimated, generating inaccurate conclusions about the physical quality of the soil under study. PMID:24672338

  2. Quantitative x-ray microtomography with a conventional source

    NASA Astrophysics Data System (ADS)

    Davis, Graham; Evershed, Anthony; Elliott, James; Mills, David

    2010-09-01

    In 1981, Elliott and Dover designed an X-ray microtomography scanner as a means of measuring the local mineral concentration in teeth. Although slow, this first generation system gave accurate measurements of the X-ray linear attenuation coefficient (LAC) due to its use of energy dispersive photon counting apparatus. Attaining such accuracy with integrating detectors in third generation scanners is difficult, but has been the goal of our ongoing development. The current "MuCat 2" system uses a 6cm square CCD chip with a parallel fibre-optic faceplate coupled to a CsI scintillator. Time delay integration readout (with sliding camera) is used to eliminate ring artefacts and enable high dynamic range X-ray projections to be acquired. The beam is collimated with a moving aperture (tracking the camera) to reduce X-ray scatter. Beam hardening is reduced by the use of filtering and corrected using data from an aluminium step wedge to optimise a model of polychromatic X-ray generation, attenuation and detection. Adjustments can be made to the model to allow for known specimen composition. Projections are corrected for distortion and repeatable wobble in the rotation stage. Where high absolute accuracy of the LAC is required, a pure aluminium wire is included in the scan and used to "fine-tune" the grey level after reconstruction.

  3. Electrical conductivity anomaly and X-ray photoelectron spectroscopy investigation of YCr1-xMnxO3 negative temperature coefficient ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Zhao, Qing; Chang, Aimin; Li, Yiyu; Liu, Yin; Wu, Yiquan

    2014-03-01

    Electrical conductivity anomaly of perovskite-type YCr1-xMnxO3 negative temperature coefficient (NTC) ceramics produced by spark plasma sintering (SPS) has been investigated by using defect chemistry theory combination with X-ray photoelectron spectroscopy (XPS) analysis. From the results of the ln?-1/T curves and the XPS analysis, it can be considered that YCr1-xMnxO3 ceramics exhibit the hopping conductivity. The major carriers in YCrO3 are holes, which are compensated by the oxygen vacancies produced due to the introduction of Mn ions. The Mn4+ ion contents increase monotonically in the range of 0.2 ? x ? 0.5. The resistivity increases at first and then decreases with increasing Mn contents, which has the same varying tendency with activation energy. The electrical conductivity anomaly appearing in these ceramics may be due to the variation of Cr4+ and Mn4+ ions concentration as Mn content changes.

  4. Images of soft materials: a 3D visualization of interior of the sample in terms of attenuation coefficient

    NASA Astrophysics Data System (ADS)

    Golosio, B.; Brunetti, A.; Cesareo, R.; Amendolia, S. R.; Rao, D. V.; Seltzer, S. M.

    2001-06-01

    Images of soft materials are obtained using image intensifier based X-ray system (Rao et al., Nucl. Instr. and Meth. A 437 (1999) 141). The interior of the soft material is visualized using the novel software in order to know the distribution of attenuation coefficient in terms of density. The novel software is based mainly on graphical library and applicable to several operating systems without any change. It can be applied to several applications starting from biomedical to industries, for example, quality control. The results for walnut and brew tooth are presented as a set of images from the internal parts of the sample. A description of the principal parameters required for tomographic visualization is given and some results based on this technique are reported and discussed.

  5. Monitoring macro voids in mortar by X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Birgul, Recep

    2008-11-01

    In this study, X-ray computed tomography (CT) was shown to be a capable technique to quantify the evolution of macro voids and to monitor the strength development of mortar specimens. Two-dimensional image analysis was utilized to extract quantitative information from the X-ray CT data. In particular, monitoring and quantifying macro voids were of interest; thus nondestructive X-ray measurements were conducted on the same mortar specimen at different days. X-ray attenuations were then transformed into CT numbers, which was actually a map of linear attenuation coefficients in terms of Hounsfield Units; this map can be presented as a two-dimensional image. Analyses performed on these images revealed that the porosity of the mortar specimen reduced from 3.94% at the beginning to 3.06% at the end of the monitoring period.

  6. The remote sensing algorithm of spectral diffuse attenuation coefficient of ocean

    Microsoft Academic Search

    Qiankun Zhu; Xianqiang He; Zhihua Mao; Fang Gong

    2008-01-01

    Diffuse attenuation coefficient is an apparent optical property (AOP) which directly links to the inherent optical properties in ocean color remote sensing. So far, the study on the satellite retrieve algorithm of water diffuse attenuation coefficient has not been deeply-going, which is mainly discussed using the bands-ratio methods based on the in situ data. Only a few scientists apply the

  7. Skull x-ray

    MedlinePLUS

    X-ray - head; X-ray - skull; Skull radiography; Head x-ray ... You will be asked to lie on the x-ray table or sit in a chair. Your ... there is little or no discomfort during an x-ray. If there is a head injury , positioning ...

  8. A realistic projection simulator for laboratory based X-ray micro-CT

    NASA Astrophysics Data System (ADS)

    Dhaene, Jelle; Pauwels, Elin; De Schryver, Thomas; De Muynck, Amelie; Dierick, Manuel; Van Hoorebeke, Luc

    2015-01-01

    In X-ray computed tomography (CT) each voxel of the reconstructed image contains a calculated grey value which represents the linear attenuation coefficient for the materials in that voxel. Conventional laboratory based CT scanners use polychromatic X-ray sources and integrating detectors with an energy dependent efficiency. Consequently the reconstructed attenuation coefficients will depend on the spectrum of the source and the spectral sensitivity of the detector. Beam hardening will alter the spectrum significantly as the beam propagates through the sample. Therefore, sample composition and shape will affect the reconstructed attenuation coefficients as well. A polychromatic projection simulator has been developed at the 'Centre for X-ray Tomography' of the Ghent University (UGCT) which takes into account the aforementioned variables, allowing for complete and realistic simulations of CT scans for a wide range of geometrical setups. Monte Carlo simulations of the X-ray tubes and detectors were performed to model their spectral behaviour. In this paper, the implementation and features of the program are discussed. Simulated and real CT scans are compared to demonstrate the quantitative correctness of the simulations. Experiments performed at two different UGCT scanners yield a maximum deviation of 3.9% and 6.5% respectively, between the measured and simulated reconstructed attenuation coefficients.

  9. Biomedical elemental analysis and imaging using synchrotron x-ray microscopy

    SciTech Connect

    Jones, K.W.; Gordon, B.M.; Schidlovsky, G.; Spanne, P.; Dejun, Xue (Brookhaven National Lab., Upton, NY (USA)); Bockman, R.S. (Hospital for Special Surgery, New York, NY (USA)); Saubermann, A.J. (State Univ. of New York, Stony Brook, NY (USA). Health Science Center)

    1990-01-01

    The application of synchrotron x-ray microscopy to biomedical research is currently in progress at the Brookhaven National Synchrotron Light Source (NSLS). The current status of the x-ray microscope (XRM) is reviewed from a technical standpoint. Some of the items considered are photon flux, spatial resolution, quantitation, minimum detection limits, and beam-induced specimen damage. Images can be produced by measurement of fluorescent x rays or of the attenuation of the incident beam by the specimen. Maps of the elemental distributions or linear attenuation of the incident beam by the specimen. Maps of the elemental distributions or linear attenuation coefficients can be made by scanning the specimen past the beam. Computed microtomography (CMT) can be used for non- destructive images through the specimen in either the emission or absorption mode. Examples of measurements made with the XRM are given.

  10. Influence of resonant Raman scattering in the elemental analysis using X-ray emission based techniques

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Singh, Gurjeet; Kumar, Sanjeev; Mehta, D.; Singh, Nirmal

    2010-08-01

    A tabulation of characteristic X-ray energies across the periodic table are provided where those X-rays are expected to result in a significant fractional resonant Raman scattering (RRS) contribution to the X-ray attenuation from a particular shell/subshell of the same or another element. The tabulations can be considered as guideline so as to know what can be expected due to RRS in typical photon- and particle-induced X-ray emission spectrometry. The RRS contribution is not included in the available theoretical attenuation coefficients, which are generally used in estimation of the matrix corrections in routine quantitative elemental analysis based on various X-ray emission techniques. The radiative RRS peaks can also interfere with normal X-ray spectrum and influence the elemental analysis. The RRS cross-section depends upon the energy difference of the X-ray energy and the shell/subshell ionization threshold taken in the units of the shell/subshell energy width, density of available states near the Fermi level, and the band structure in case the element is in the solid form. Some aspects of the dependence of the RRS contribution on the chemical forms of the elements are also discussed.

  11. A three-dimensional x-ray scattering system for multi-parameter imaging of the human head

    Microsoft Academic Search

    Faysal El Khettabi; Ilan Yaar; Esam M A Hussein

    2003-01-01

    This work examines the suitability of a non-rotating one-side 3D x-ray scatter system for imaging the human head. The system simultaneously produces images of the x-ray attenuation coefficients at two photon energies, as well as an image of the electron density. The system relies on measuring the scattered radiation at two directions orthogonal to an incident beam that scans the

  12. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1991-01-01

    The annual progress report on Cosmic X Ray Physics for the period 1 Jan. to 31 Dec. 1990 is presented. Topics studied include: soft x ray background, new sounding rocket payload: x ray calorimeter, and theoretical studies.

  13. Cosmic x ray physics

    NASA Technical Reports Server (NTRS)

    Mccammon, Dan; Cox, D. P.; Kraushaar, W. L.; Sanders, W. T.

    1990-01-01

    The annual progress report on Cosmic X Ray Physics is presented. Topics studied include: the soft x ray background, proportional counter and filter calibrations, the new sounding rocket payload: X Ray Calorimeter, and theoretical studies.

  14. X-ray universe

    SciTech Connect

    Tucker, W.; Giacconi, R.

    1985-01-01

    This book is a selective and personal history of x-ray astronomy. The x-ray universe is considered along with the sensible world, historical aspects regarding the discovery and utilization of x-rays, the pioneers of x-ray astronomy, the discovery of an x-ray star, the riddle of the x-ray stars, developments leading to the Uhuru (x-ray Explorer) satellite and the study of neutron stars and black holes, the x-ray sky, a telescope for x-rays, the Einstein observatory (HEAO-2), stellar coronas and supernovas, active galaxies and quasars, clusters of galaxies and the missing mass, and the cosmic x-ray background. Attention is also given to NASA's Advanced x-Ray Astrophysics Facility, which will open a permanent window on the x-ray universe.

  15. Joint x-ray

    MedlinePLUS

    X-ray - joint; Arthrography; Arthrogram ... x-ray technologist will help you position the joint to be x-rayed on the table. Once in place, pictures are taken. The joint may be moved into other positions for more ...

  16. Computer Reconstructed X-Ray Imaging

    Microsoft Academic Search

    G. N. Hounsfield

    1979-01-01

    Computed tomography is a method for obtaining a series of radiographic pictures of contiguous slices through a solid object such as the human body. Each picture is computed from a set of X-ray transmission measurements and represents the distribution of X-ray attenuation in the slice. The high sensitivity of the method to changes in both density and atomic number has

  17. Improvement of analysis precision upon the atomic number and electron density measurement by the dual x-ray CT

    NASA Astrophysics Data System (ADS)

    Imura, Yukino; Morii, Hisashi; Koike, Akifumi; Okunoyama, Takaharu; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

    2010-08-01

    To identify the factor impairing the material identification parameters, which is provided by the dual-energy X-ray computed tomography method using a conventional X-ray tube and a CdTe detector, linear attenuation coefficient was measured by the radioactivity of radio isotopes and compared with theoretical figure. In our study, the atomic number and the electron density is calculated from the linear attenuation coefficient obtained in CT measurement by 64-channel CdTe line detector. To estimate accuracy of CdTe line sensor, it is needed to obtain the linear attenuation coefficient accurately. Using a single detector, the linear attenuation coefficient is verified for accuracy. The energy resolution of CdTe detectors and the method of reconstruction are discussed.

  18. Spin and its evolution for isolated neutron stars and X-ray binaries: the determination of the 'Diffusion coefficients' and Spindown Theorem

    E-print Network

    V. M. Lipunov; S. B. Popov

    1996-09-26

    In this work we give detail consideration of the possible scenario of evolution of isolated neutron stars and determine some characteristics of X-ray pulsars from their spin period evolution (the paper containes more detailed abstract).

  19. Correlation between Small-Angle X-ray Scattering spectra and apparent diffusion coefficients in the study of structure and interaction of sodium taurodeoxycholate micelles.

    PubMed

    Cozzolino, Sara; Galantini, Luciano; Leggio, Claudia; Pavel, Nicolae Viorel

    2005-04-01

    Small-Angle X-ray Scattering (SAXS) and Dynamic Light Scattering (DLS) measurements were carried out on aqueous micellar solutions of the ionic biological detergent sodium taurodeoxycholate (NaTDC). Apparent diffusion coefficients (D(app)) and SAXS spectra of NaTDC 0.1 M solutions at different ionic strengths (0.1-0.3 M NaCl) were reported. A comparative analysis of SAXS spectra and D(app) data was performed to infer information on particle structure and interaction potential. Uniform particles with a spherical, an oblate, and a prolate symmetry were used to model the micelles in the data interpretation. A hard-core interaction shell of suitable thickness and a screened Coulomb potential of the electric double layer (EDL potential) were alternatively used to represent the long-range repulsive tail of the interaction potential. The Percus Yevick and the Rescaled Mean Spherical Approximation were applied. To compare the data of the two techniques, for each sample, a D(app) was calculated from the SAXS best-fitting geometrical parameters and interparticle structure factor of the micelles. Hence, a fitting procedure involving both the scattering and D(app) data was performed. The interpretation of SAXS spectra does not allow the discrimination between the oblate and the prolate symmetries of the aggregates. On the other hand, the comparison of calculated and experimental D(app) values indicates that the prolate ellipsoid is better suited to represent the micelle shape. Moreover, the agreement between calculated and experimental D(app) values is sensitively better at the lowest NaCl concentration when the EDL potential is used. A rodlike micellar growth and a progressive screening of the electrostatic interactions is testified by the trends of best-fitting parameters as a function of the added electrolyte. PMID:16851673

  20. Calculation and validation of the use of effective attenuation coefficient for attenuation correction in In-111 SPECT.

    PubMed

    Seo, Youngho; Wong, Kenneth H; Hasegawa, Bruce H

    2005-12-01

    Nuclear medicine tracers using 111In as a radiolabel are increasing in their use, especially in the domain of oncologic imaging. In these applications, it often is critical to have the capability of quantifying radionuclide uptake and being able to relate it to the biological properties of the tumor. However, images from single photon emission computed tomography (SPECT) can be degraded by photon attenuation, photon scattering, and collimator blurring; without compensation for these effects, image quality can be degraded, and accurate and precise quantification is impossible. Although attenuation correction for SPECT is becoming more common, most implementations can only model single energy radionuclides such as 99mTc and 123I. Thus, attenuation correction for 111In is challenging because it emits two photons (171 and 245 keV) at nearly equal rates (90.2% and 94% emission probabilities). In this paper, we present a method of calculating a single "effective" attenuation coefficient for the dual-energy emissions of 111In, and that can be used to correct for photon attenuation in radionuclide images acquired with this radionuclide. Using this methodology, we can derive an effective linear attenuation coefficient Micro(eff) and an effective photon energy E(eff) based on the emission probabilities and linear attenuation coefficients of the 111In photons. This approach allows us to treat the emissions from 111In as a single photon with an effective energy of 210 keV. We obtained emission projection data from a tank filled with a uniform solution of 111In. The projection data were reconstructed using an iterative maximum-likelihood algorithm with no attenuation correction, and with attenuation correction assuming photon energies of 171, 245, and 210 keV (the derived E(eff)). The reconstructed tomographic images demonstrate that the use of no attenuation correction, or correction assuming photon energies of 171 or 245 keV introduces inaccuracies into the reconstructed radioactivity distribution when compared against the effective energy method. In summary, this work provides both a theoretical framework and experimental methodology of attenuation correction for the dual-energy emissions from 111In. Although these results are specific to 111In, the foundation could easily be extended to other multiple-energy isotopes. PMID:16475761

  1. Factors That Attenuate the Correlation Coefficient and Its Analogs.

    ERIC Educational Resources Information Center

    Dolenz, Beverly

    The correlation coefficient is an integral part of many other statistical techniques (analysis of variance, t-tests, etc.), since all analytic methods are actually correlational (G. V. Glass and K. D. Hopkins, 1984). The correlation coefficient is a statistical summary that represents the degree and direction of relationship between two variables.…

  2. A generalized porosity formalism for isotropic and anisotropic effective opacity and its effects on X-ray line attenuation in clumped O star winds

    NASA Astrophysics Data System (ADS)

    Sundqvist, Jon O.; Owocki, Stanley P.; Cohen, David H.; Leutenegger, Maurice A.; Townsend, Richard H. D.

    2012-02-01

    We present a generalized formalism for treating the porosity-associated reduction in continuum opacity that occurs when individual clumps in a stochastic medium become optically thick. As in previous work, we concentrate on developing bridging laws between the limits of optically thin and thick clumps. We consider geometries resulting in either isotropic or anisotropic effective opacity, and, in addition to an idealized model in which all clumps have the same local overdensity and scale, we also treat an ensemble of clumps with optical depths set by Markovian statistics. This formalism is then applied to the specific case of bound-free absorption of X-rays in hot star winds, a process not directly affected by clumping in the optically thin limit. We find that the Markov model gives surprisingly similar results to those found previously for the single-clump model, suggesting that porous opacity is not very sensitive to details of the assumed clump distribution function. Further, an anisotropic effective opacity favours escape of X-rays emitted in the tangential direction (the 'venetian blind' effect), resulting in a 'bump' of higher flux close to line centre as compared to profiles computed from isotropic porosity models. We demonstrate how this characteristic line shape may be used to diagnose the clump geometry, and we confirm previous results that for optically thick clumping to significantly influence X-ray line profiles, very large porosity lengths, defined as the mean free path between clumps, are required. Moreover, we present the first X-ray line profiles computed directly from line-driven instability simulations using a 3D patch method, and find that porosity effects from such models also are very small. This further supports the view that porosity has, at most, a marginal effect on X-ray line diagnostics in O stars, and therefore that these diagnostics do indeed provide a good 'clumping insensitive' method for deriving O star mass-loss rates.

  3. A Generalised Porosity Formalism for Isotropic and Anisotropic Effective Opacity and its Effects on X-ray Line Attenuation in Clumped O Star Winds

    NASA Technical Reports Server (NTRS)

    Sundqvist, Jon O.; Owocki, Stanley P.; Cohen, David H.; Leutenegger, Maurice A.

    2011-01-01

    We present a generalised formalism for treating the porosity-associated reduction in continuum opacity that occurs when individual clumps in a stochastic medium become optically thick. As in previous work, we concentrate on developing bridging laws between the limits of optically thin and thick clumps. We consider geometries resulting in either isotropic or anisotropic effective opacity, and, in addition to an idealised model in which all clumps have the same local overdensity and scale, we also treat an ensemble of clumps with optical depths set by Markovian statistics. This formalism is then applied to the specific case of bound-free absorption of X- rays in hot star winds, a process not directly affected by clumping in the optically thin limit. We find that the Markov model gives surprisingly similar results to those found previously for the single clump model, suggesting that porous opacity is not very sensitive to details of the assumed clump distribution function. Further, an anisotropic effective opacity favours escape of X-rays emitted in the tangential direction (the venetian blind effect), resulting in a bump of higher flux close to line centre as compared to profiles computed from isotropic porosity models. We demonstrate how this characteristic line shape may be used to diagnose the clump geometry, and we confirm previous results that for optically thick clumping to significantly influence X-ray line profiles, very large porosity lengths, defined as the mean free path between clumps, are required. Moreover, we present the first X-ray line profiles computed directly from line-driven instability simulations using a 3-D patch method, and find that porosity effects from such models also are very small. This further supports the view that porosity has, at most, a marginal effect on X-ray line diagnostics in O stars, and therefore that these diagnostics do indeed provide a good clumping insensitive method for deriving O star mass-loss rates.

  4. A Generalised Porosity Formalism for Isotropic and Anisotropic Effective Opacity and Its Effects on X-ray Line Attenuation in Clumped O Star Winds

    NASA Technical Reports Server (NTRS)

    Sundqvist, Jon O.; Owocki, Stanley P.; Cohen, David H.; Leutenegger, Maurice A.; Townsend, Richard H. D.

    2002-01-01

    We present a generalised formalism for treating the porosity-associated reduction in continuum opacity that occurs when individual clumps in a stochastic medium become optically thick. As in previous work, we concentrate on developing bridging laws between the limits of optically thin and thick clumps. We consider geometries resulting in either isotropic or anisotropic effective opacity, and, in addition to an idealised model in which all clumps have the same local overdensity and scale, we also treat an ensemble of clumps with optical depths set by Markovian statistics. This formalism is then applied to the specific case of bound-free absorption of X- rays in hot star winds, a process not directly affected by clumping in the optically thin limit. We find that the Markov model gives surprisingly similar results to those found previously for the single clump model, suggesting that porous opacity is not very sensitive to details of the assumed clump distribution function. Further, an anisotropic effective opacity favours escape of X-rays emitted in the tangential direction (the venetian blind effect), resulting in a bump of higher flux close to line centre as compared to profiles computed from isotropic porosity models. We demonstrate how this characteristic line shape may be used to diagnose the clump geometry, and we confirm previous results that for optically thick clumping to significantly influence X-ray line profiles, very large porosity lengths, defined as the mean free path between clumps, are required. Moreover, we present the first X-ray line profiles computed directly from line-driven instability simulations using a 3-D patch method, and find that porosity effects from such models also are very small. This further supports the view that porosity has, at most, a marginal effect on X-ray line diagnostics in O stars, and therefore that these diagnostics do indeed provide a good clumping insensitive method for deriving O star mass-loss rates.

  5. Abdominal x-ray

    MedlinePLUS

    Abdominal film; X-ray - abdomen; Flat plate; KUB x-ray ... Diagnose a pain in the abdomen or unexplained nausea Identify suspected problems in the urinary system, such as a kidney stone Identify blockage in the intestine Locate ...

  6. X-Ray Lasers

    ERIC Educational Resources Information Center

    Chapline, George; Wood, Lowell

    1975-01-01

    Outlines the prospects of generating coherent x rays using high-power lasers and indentifies problem areas in their development. Indicates possible applications for coherent x rays in the fields of chemistry, biology, and crystallography. (GS)

  7. The role of the reflection coefficient in precision measurement of ultrasonic attenuation

    NASA Technical Reports Server (NTRS)

    Generazio, E. R.

    1984-01-01

    Ultrasonic attenuation measurements using contact, pulse-echo techniques are sensitive to surface roughness and couplant thickness variations. This can reduce considerable inaccuracies in the measurement of the attenuation coefficient for broadband pulses. Inaccuracies arise from variations in the reflection coefficient at the buffer-couplant-sample interface. The reflection coefficient is examined as a function of the surface roughness and corresponding couplant thickness variations. Interrelations with ultrasonic frequency are illustrated. Reliable attenuation measurements are obtained only when the frequency dependence of the reflection coefficient is incorporated in signal analysis. Data are given for nickel 200 samples and a silicon nitride ceramic bar having surface roughness variations in the 0.3 to 3.0 microns range for signal bandwidths in the 50 to 100 MHz range.

  8. Quantitative edge illumination x-ray phase contrast tomography

    NASA Astrophysics Data System (ADS)

    Hagen, Charlotte K.; Diemoz, Paul C.; Endrizzi, Marco; Rigon, Luigi; Dreoosi, Diego; Arfelli, Fulvia; Lopez, Frances C. M.; Longo, Renata; Olivo, Alessandro

    2014-09-01

    This article discusses two experimental setups of edge illumination (EI) x-ray phase contrast imaging (XPCi) as well as the theory that is required to reconstruct quantitative tomographic maps using established methods, e.g. filtered back projection (FBP). Tomographic EI XPCi provides the option to reconstruct volumetric maps of different physical quantities, amongst which are the refractive index decrement from unity and the absorption coefficient, which can be used for dual-mode imaging. EI XPCi scans of a custom-built wire phantom using synchrotron and x-ray tube generated radiation were carried out, and tomographic maps of both parameters were reconstructed. This article further discusses the theoretical basis for the tomographic reconstruction of images showing combined phase and attenuation contrast. Corresponding experimental results are presented.

  9. X-ray spectropolarimeter

    SciTech Connect

    Baronova, E. O.; Stepanenko, M. M.; Stepanenko, A. M. [RRC Kurchatov Institute, 123182 Moscow (Russian Federation)

    2008-08-15

    We have constructed a novel single-crystal x-ray spectropolarimeter that separates spatially the two perpendicularly polarized components of an x-ray beam. We have tested this device by using an x-ray tube, and confirmed its performance to be satisfactory as expected from its design.

  10. Investigation of photon attenuation coefficient of some building materials used in Turkey

    NASA Astrophysics Data System (ADS)

    Dogan, B.; Altinsoy, N.

    2015-03-01

    In this study, some building materials regularly used in Turkey, such as concrete, gas concrete, pumice and brick have been investigated in terms of mass attenuation coefficient at different gamma-ray energies. Measurements were carried out by gamma spectrometry containing NaI(Tl) detector. Narrow beam gamma-ray transmission geometry was used for the attenuation measurements. The results are in good agreement with the theoretical calculation of XCOM code.

  11. X-Ray Data Booklet X-RAY DATA BOOKLET

    E-print Network

    Meagher, Mary

    X-Ray Data Booklet X-RAY DATA BOOKLET Center for X-ray Optics and Advanced Light Source Lawrence Berkeley National Laboratory Introduction X-Ray Properties of Elements Electron Binding Energies X-Ray Levels of Few Electron Ions Now Available Order X-Ray Data Booklet http://xdb.lbl.gov/ (1 of 3) [2

  12. Studies on effective atomic numbers, electron densities and mass attenuation coefficients in Au alloys.

    PubMed

    Han, I; Demir, L

    2010-01-01

    The total mass attenuation coefficients (mu/rho) for pure Au and Au99Be1, Au88Ge12, Au95Zn5 alloys were measured at 59.5 and 88.0 keV photon energies. The samples were irradiated with 241Am and 109Cd radioactive point source using transmission arrangement. The gamma- rays were counted by a Si(Li) detector with resolution of 160 eV at 5.9 keV. Total atomic and electronic cross-sections (sigmat and sigmae), effective atomic and electron densities (Zeff and Nel) were determined using the obtained mass attenuation coefficients for investigated Au alloys. The theoretical mass attenuation coefficients of each alloy were estimated using mixture rule. PMID:20421703

  13. Effect of external magnetic field on attenuation coefficient for magnetic substances.

    PubMed

    Kumar Gupta, Manoj; Dhaliwal, A S; Kahlon, K S

    2014-10-29

    The measurement of attenuation coefficient of some magnetic substances, to include diamagnetic: Cu, Zn, Ag, Te, Au, Pb, and Perspex; paramagnetic: Al, Ti, Mo, Dy, Ho, and Pt and ferromagnetic substances: Fe, Co, Ni, Gd, FeO, NiO, FeS, and Fe2O3, both in the presence and absence of an external magnetic field has been carried out using narrow beam transmission geometry by using gamma ray photons of incident energy 59.54keV from 100mCi, (241)Am point source. It was observed very keenly that the value of linear attenuation coefficient of various substances mentioned above decreased remarkably. It varied in the range of 1-2%, 2-6% and 6-9% for diamagnetic, paramagnetic and ferromagnetic substances respectively in the presence of an external magnetic field. Measured results elucidated it very clearly that linear attenuation coefficient at H=0T, 0.6T and 1.2T continued to decrease with a regular increase of magnetic field. It is also manifested that measurements of linear attenuation coefficient is not affected with the change in thickness of the given substance. Within error limits (1-3%) variations are observed with increases of thickness along with magnetic field. Further to it the obtained results of linear attenuation coefficient without magnetic field (H=0T) were compared with theoretical data tables of FFAST and WinXCOM. It was established that values obtained are well within the experimental errors. To the best of our knowledge no other study in relation to the effect of linear attenuation coefficient in the presence of magnetic field available as precedence. PMID:25464197

  14. A calibration transmission method to determine the gamma-ray linear attenuation coefficient without a collimator.

    PubMed

    Byun, Jong-In; Yun, Ju-Yong

    2015-08-01

    It is shown that the gamma-ray linear attenuation coefficient of a sample with unknown chemical composition can be determined through a systematic calibration of the correlation between the linear attenuation coefficient, gamma-ray energy and the relative degree of attenuation. For calibration, H2O, MnO2, NaCl, Na2CO3 and (NH4)2SO4 were used as reference materials. Point-like gamma-ray sources with modest activity of approximately 37kBq, along with an HPGe detector, were used in the measurements. A semi-empirical formula was derived to calculate the linear attenuation coefficients as a function of the relative count rate and the gamma-ray energy. The method was applied to the determination of the linear attenuation coefficients for K2CrO4 and SiO2 test samples in the same setup used in calibration. The experimental result agreed well with the ones calculated by elementary data. PMID:25997111

  15. The Physics Analysis of a Gas Attenuator with Argon as a Working Gas

    Microsoft Academic Search

    D. D. Ryutov; R. M. Bionta; M. A. McKernan; S. Shen; J. W. Trent

    2010-01-01

    A gas attenuator is an important element of the LCLS facility. The attenuator must operate in a broad range of x-ray energies, provide attenuation coefficient between 1 and 10 with the accuracy of 1% and, at the same time, be reliable and allow for many months of un-interrupted operation. S. Shen has recently carried out a detailed design study of

  16. Quantification of effective attenuation coefficients using continuous wavelet transform of photoacoustic signals.

    PubMed

    Hirasawa, Takeshi; Fujita, Masanori; Okawa, Shinpei; Kushibiki, Toshihiro; Ishihara, Miya

    2013-12-10

    A method for quantifying the effective attenuation coefficients of optical absorbers by using the continuous wavelet transform (CWT) to calculate the time-resolved frequency spectra of photoacoustic signals is proposed. Because the coefficients can be quantified according to the relative intensity of the frequency content of the signals, it is unnecessary to determine the fluences. A computational simulation reveals that the time-resolved frequency spectra exhibit better correlation with the coefficients than do power spectra calculated using a Fourier transformation. The CWT-based method was experimentally verified, and the coefficients were quantified with mean square error of 2.0??cm(-1). PMID:24513902

  17. Revealing the powdering methods of black makeup in Ancient Egypt by fitting microstructure based Fourier coefficients to the whole x-ray diffraction profiles of galena

    Microsoft Academic Search

    T. Ungár; P. Martinetto; G. Ribárik; E. Dooryhée; Ph. Walter; M. Anne

    2002-01-01

    Galena (PbS) is a major ingredient in ancient Egyptian eye makeup. The microstructure of PbS in Egyptian cosmetic powders is used as a fingerprint and is matched with the microstructures produced artificially in geological galena minerals. The microstructure of PbS is determined by x-ray diffraction peak profile analysis in terms of dislocation density, crystallite size, and size distribution. High-resolution powder

  18. An Ideal Observer for a Model of X-Ray Imaging in Breast Parenchymal Tissue

    Microsoft Academic Search

    Craig K. Abbey; John M. Boone

    2008-01-01

    We develop and evaluate an ideal observer for model of the 3D spatial distribution of x-ray attenuation coefficients in the\\u000a breast. This model relies on thresholding of an underlying Gaussian random field to generate binary objects representing the\\u000a distribution of adipose and glandular tissue in the breast parenchyma. Our motivation is to evaluate an emerging breast CT\\u000a device for breast

  19. X-ray binaries

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

  20. X-ray imager

    Microsoft Academic Search

    Grachik H. Avetisyan; Alexej K. Erkin; Vladimir B. Kulikov; Vitalij P. Kotov; Yuri A. Kuznetsov; Vladimir M. Trubnikov

    1997-01-01

    The paper presents the findings of an investigation into some characteristics of an X-ray imager. The imager is an assembly of modules, each incorporating a linear array of GaAs detectors connected electrically to a CCD multiplexer. The X-ray imager can be used in industrial and medical X-ray diagnostic equipment. Bibtex entry for this abstract Preferred format for this abstract (see

  1. X-ray transfer

    SciTech Connect

    Castor, J.I.

    1992-03-01

    The computational techniques for treating radiative transfer in general, and x-ray transfer in particular, are reviewed, with emphasis on the difficult problems associated with systems that are not in local thermodynamic equilibrium. Some special aspects of x-ray transfer are mentioned. The computer code ALTAIR, developed at LLNL to solve such problems, is described briefly, with an example of x-ray fluorescence in a Seyfert galaxy. Some of the prospects for experimental tests of x-ray radiative transfer theory are considered.

  2. A patient-equivalent attenuation phantom for estimating patient exposures from automatic exposure controlled x-ray examinations of the abdomen and lumbo-sacral spine

    SciTech Connect

    Conway, B.J.; Duff, J.E.; Fewell, T.R.; Jennings, R.J.; Rothenberg, L.N.; Fleischman, R.C. (Food and Drug Administration, Rockville, MD (USA))

    1990-05-01

    The Joint Commission on Accreditation of Healthcare Organizations requires diagnostic radiology facilities to known the approximate amount of radiation received by an average patient during radiographic examinations at the facility. Automatic exposure controlled (AEC) techniques are used for many of these exams, and a standard patient-equivalent phantom is necessary when estimating patient exposure on such systems. This is of particular importance if exposures are to be compared among AEC systems with different entrance x-ray spectra. We have developed a phantom, LucA1 Abdomen, to facilitate determining the average patient exposure from AEC anteroposterior (AP) abdomen and lumbo-sacral (LS) spine radiography. The phantom is relatively lightweight, transportable, sturdy, and made of readily available inexpensive materials (Lucite and aluminum). It accurately simulates the primary and scatter transmission through the soft tissue and L-4 spinal regions of a patient-equivalent anthropomorphic phantom for x-ray spectra typically used in abdomen/LS spine radiography. A clinical evaluation to verify the patient-equivalence of three commercial anthropomorphic phantoms (Humanoid, Rando, 3-M) and two acrylic/aluminum phantoms (ANSI and LucA1 Abdomen) has been conducted. The design and development of the LucA1 Abdomen phantom and the evaluation of all phantoms is described.

  3. Extending Coastal Zone Color Scanner estimates of the diffuse attenuation coefficient into Case II waters

    Microsoft Academic Search

    Richard W. Gould; Robert A. Arnone

    1994-01-01

    An iterative technique has been developed to improve coastal zone color scanner (CZCS) estimates of upwelled subsurface water radiances (Lu) in Case II waters. Regional relationships between the diffuse attenuation coefficient measured at 490 nm (K490) and Lu measured at 443, 520, and 550 nm were developed using data collected in the northern Gulf of Mexico in April 1993. These

  4. Modeling the vertical distributions of downwelling plane irradiance and diffuse attenuation coefficient in optically deep waters

    Microsoft Academic Search

    Xiaoju Pan; Richard C. Zimmerman

    2010-01-01

    The diffuse attenuation coefficient (Kd) is critical to understand the vertical distribution of underwater downwelling irradiance (Ed). Theoretically Ed is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kd is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse

  5. Emission-based estimation of lung attenuation coefficients for attenuation correction in time-of-flight PET/MR

    NASA Astrophysics Data System (ADS)

    Mehranian, Abolfazl; Zaidi, Habib

    2015-06-01

    In standard segmentation-based MRI-guided attenuation correction (MRAC) of PET data on hybrid PET/MRI systems, the inter/intra-patient variability of linear attenuation coefficients (LACs) is ignored owing to the assignment of a constant LAC to each tissue class. This can lead to PET quantification errors, especially in the lung regions. In this work, we aim to derive continuous and patient-specific lung LACs from time-of-flight (TOF) PET emission data using the maximum likelihood reconstruction of activity and attenuation (MLAA) algorithm. The MLAA algorithm was constrained for estimation of lung LACs only in the standard 4-class MR attenuation map using Gaussian lung tissue preference and Markov random field smoothness priors. MRAC maps were derived from segmentation of CT images of 19 TOF-PET/CT clinical studies into background air, lung, soft tissue and fat tissue classes, followed by assignment of predefined LACs of 0, 0.0224, 0.0864 and 0.0975?cm?1, respectively. The lung LACs of the resulting attenuation maps were then estimated from emission data using the proposed MLAA algorithm. PET quantification accuracy of MRAC and MLAA methods was evaluated against the reference CT-based AC method in the lungs, lesions located in/near the lungs and neighbouring tissues. The results show that the proposed MLAA algorithm is capable of retrieving lung density gradients and compensate fairly for respiratory-phase mismatch between PET and corresponding attenuation maps. It was found that the mean of the estimated lung LACs generally follow the trend of the reference CT-based attenuation correction (CTAC) method. Quantitative analysis revealed that the MRAC method resulted in average relative errors of???5.2???±???7.1% and???6.1???±???6.7% in the lungs and lesions, respectively. These were reduced by the MLAA algorithm to???0.8???±???6.3% and???3.3???±???4.7%, respectively. In conclusion, we demonstrated the potential and capability of emission-based methods in deriving patient-specific lung LACs to improve the accuracy of attenuation correction in TOF PET/MR imaging, thus paving the way for their adaptation in the clinic.

  6. Emission-based estimation of lung attenuation coefficients for attenuation correction in time-of-flight PET/MR.

    PubMed

    Mehranian, Abolfazl; Zaidi, Habib

    2015-06-21

    In standard segmentation-based MRI-guided attenuation correction (MRAC) of PET data on hybrid PET/MRI systems, the inter/intra-patient variability of linear attenuation coefficients (LACs) is ignored owing to the assignment of a constant LAC to each tissue class. This can lead to PET quantification errors, especially in the lung regions. In this work, we aim to derive continuous and patient-specific lung LACs from time-of-flight (TOF) PET emission data using the maximum likelihood reconstruction of activity and attenuation (MLAA) algorithm. The MLAA algorithm was constrained for estimation of lung LACs only in the standard 4-class MR attenuation map using Gaussian lung tissue preference and Markov random field smoothness priors. MRAC maps were derived from segmentation of CT images of 19 TOF-PET/CT clinical studies into background air, lung, soft tissue and fat tissue classes, followed by assignment of predefined LACs of 0, 0.0224, 0.0864 and 0.0975?cm(-1), respectively. The lung LACs of the resulting attenuation maps were then estimated from emission data using the proposed MLAA algorithm. PET quantification accuracy of MRAC and MLAA methods was evaluated against the reference CT-based AC method in the lungs, lesions located in/near the lungs and neighbouring tissues. The results show that the proposed MLAA algorithm is capable of retrieving lung density gradients and compensate fairly for respiratory-phase mismatch between PET and corresponding attenuation maps. It was found that the mean of the estimated lung LACs generally follow the trend of the reference CT-based attenuation correction (CTAC) method. Quantitative analysis revealed that the MRAC method resulted in average relative errors of??-5.2???±???7.1% and??-6.1???±???6.7% in the lungs and lesions, respectively. These were reduced by the MLAA algorithm to??-0.8???±???6.3% and??-3.3???±???4.7%, respectively. In conclusion, we demonstrated the potential and capability of emission-based methods in deriving patient-specific lung LACs to improve the accuracy of attenuation correction in TOF PET/MR imaging, thus paving the way for their adaptation in the clinic. PMID:26047036

  7. X-ray grid-detector apparatus

    DOEpatents

    Boone, John M. (Folsom, CA); Lane, Stephen M. (Oakland, CA)

    1998-01-27

    A hybrid grid-detector apparatus for x-ray systems wherein a microchannel plate structure has an air-interspaced grid portion and a phosphor/optical fluid-filled grid portion. The grids are defined by multiple adjacent channels separated by lead-glass septa. X-rays entering the air-interspaced grid portion at an angle of impingement upon the septa are attenuated, while non-impinging x-rays pass through to the phosphor/fluid filled portion. X-ray energy is converted to luminescent energy in the phosphor/fluid filled portion and the resultant beams of light are directed out of the phosphor/optical fluid filled portion to an imaging device.

  8. X-ray beamsplitter

    DOEpatents

    Ceglio, N.M.; Stearns, D.G.; Hawryluk, A.M.; Barbee, T.W. Jr.

    1987-08-07

    An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5--50 pairs of alternate Mo/Si layers with a period of 20--250 A. The support membrane is 10--200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window. 6 figs.

  9. X-ray beamsplitter

    DOEpatents

    Ceglio, Natale M. (Livermore, CA); Stearns, Daniel S. (Mountain View, CA); Hawryluk, Andrew M. (Modesto, CA); Barbee, Jr., Troy W. (Palo Alto, CA)

    1989-01-01

    An x-ray beamsplitter which splits an x-ray beam into two coherent parts by reflecting and transmitting some fraction of an incident beam has applications for x-ray interferometry, x-ray holography, x-ray beam manipulation, and x-ray laser cavity output couplers. The beamsplitter is formed of a wavelength selective multilayer thin film supported by a very thin x-ray transparent membrane. The beamsplitter resonantly transmits and reflects x-rays through thin film interference effects. A thin film is formed of 5-50 pairs of alternate Mo/Si layers with a period of 20-250 A. The support membrane is 10-200 nm of silicon nitride or boron nitride. The multilayer/support membrane structure is formed across a window in a substrate by first forming the structure on a solid substrate and then forming a window in the substrate to leave a free-standing structure over the window.

  10. X-Rays

    MedlinePLUS

    ... are a type of radiation called electromagnetic waves. X-ray imaging creates pictures of the inside of your body. The images show the parts of your body in different shades of black and white. ... Calcium in bones absorbs x-rays the most, so bones look white. Fat and ...

  11. X-ray

    MedlinePLUS

    ... Most experts feel that the benefits of appropriate x-ray imaging greatly outweigh any risks. Young children and babies in the womb are more sensitive to the risks of x-rays. Tell your health care provider if you think ...

  12. X-Rays

    MedlinePLUS

    ... without detail on a dental X-ray, but teeth show up much lighter. Restorations such as crowns and fillings are even denser than bone. They show up as solid, bright white areas on X-rays. Dental decay and caries (cavities) appear as darker patches. ...

  13. X-Ray Waveguides

    NASA Astrophysics Data System (ADS)

    Bukreev, Ianna; Cedola, Alessia; Pellicia, Daniele; Jark, Werner; Lagomarsino, Stefano

    2013-01-01

    This chapter deals with the fundamental properties of X-ray waveguides (WGs), whose development is a logical consequence of the theoretical and experimental work on X-ray standing waves. The different coupling modes and the formation of the wavefield inside the WG are reviewed. Some fabrication procedures and relevant applications are also briefly described.

  14. X-Rays

    NSDL National Science Digital Library

    This problem set is designed to test students' understanding of x-rays. Students are given wavelengths and asked to calculate minimum potential energy, radiation frequency, and whether or not the mineral can be used as a radiation filter. They are also asked to determine the 2-theta for different crystal face x-ray diffractions given cell edge length and radiation wavelength.

  15. X-ray binaries

    Microsoft Academic Search

    H. Schatz; K. E. Rehm

    2006-01-01

    We review the nuclear astrophysics aspects of accreting neutron stars in\\u000aX-ray binaries. We summarize open astrophysical questions in light of recent\\u000aobservations and their relation to the underlying nuclear physics. Recent\\u000aprogress in the understanding of the nuclear physics, especially of X-ray\\u000abursts, is also discussed.

  16. X-ray Spectrometry.

    ERIC Educational Resources Information Center

    Markowicz, Andrzej A.; Van Grieken, Rene E.

    1984-01-01

    Provided is a selective literature survey of X-ray spectrometry from late 1981 to late 1983. Literature examined focuses on: excitation (photon and electron excitation and particle-induced X-ray emission; detection (wavelength-dispersive and energy-dispersive spectrometry); instrumentation and techniques; and on such quantitative analytical…

  17. Diel cycles of the particulate beam attenuation coefficient under varying trophic conditions in the northwestern Mediterranean Sea: Observations and modeling

    E-print Network

    Antoine, David

    Diel cycles of the particulate beam attenuation coefficient under varying trophic conditions in the diel variability of the particulate beam attenuation coefficient (cp) were investigated at 4 and 9 m physical and trophic situations. We observed a diel cycle in cp during the winter mixing of the water

  18. Higher order parametric x rays

    NASA Astrophysics Data System (ADS)

    Osborne, Michael J.

    1991-12-01

    Parametric x-radiation (PXR) may be described as the Bragg scattering of virtual photons to produce real x-rays which satisfy the Bragg condition dsin theta = n(lambda), where theta is the angle between the electron beam direction and a crystal axis. Enhanced higher order parametric x-radiation from the (002) plane of a mosaic graphite crystal has been observed. Production of PXR of the order n = 2 exceed that from the first order, and x-rays of order up to n = 6 are readily seen. The production of higher order x-radiation is obtained by using a thick crystal where the formation and attenuation lengths are exploited to enhance higher energy x-ray formation relative to the lower energy first order x-radiation. Photons of energy 5 to 30 KeV have been measured. The experiment was conducted with a 90 MeV electron beam from the Naval Postgraduate School electron linear accelerator. A three axis target position program, Easy-Mover, was developed to allow for precision orientation of the crystal axis with respect to the electron beam.

  19. Acoustic attenuation coefficients for polycrystalline materials containing crystallites of any symmetry class.

    PubMed

    Kube, Christopher M; Turner, Joseph A

    2015-06-01

    This letter provides a theoretical extension to the elastic properties of polycrystals in order to describe elastic wave scattering from grain boundaries. The extension allows the longitudinal and shear attenuation coefficients for scattering to be derived and is valid for polycrystals containing crystallites of any symmetry class. Attenuation curves are given for polycrystalline SiO2, ZrO2, and SnF2, which contain monoclinic crystallites. This work will allow ultrasonic techniques to be applied to new classes of materials containing nontrivial microstructures. PMID:26093458

  20. Some Effects of Temperature on X-Ray Absorption

    Microsoft Academic Search

    H. S. Read

    1926-01-01

    Effect of temperature on the average atomic absorption coefficients of Ag and Ni for x-rays.-The previous results of the author showing a change with temperature of the average atomic absorption coefficients of various metals for x-rays have been confirmed in the case of Ag and Ni. The complete radiation from an x-ray tube operated at 50,000 volts was used. Heating

  1. X-ray laser

    DOEpatents

    Nilsen, Joseph (Livermore, CA)

    1991-01-01

    An X-ray laser (10) that lases between the K edges of carbon and oxygen, i.e. between 44 and 23 Angstroms, is provided. The laser comprises a silicon (12) and dysprosium (14) foil combination (16) that is driven by two beams (18, 20) of intense line focused (22, 24) optical laser radiation. Ground state nickel-like dysprosium ions (34) are resonantly photo-pumped to their upper X-ray laser state by line emission from hydrogen-like silicon ions (32). The novel X-ray laser should prove especially useful for the microscopy of biological specimens.

  2. Panoramic Dental X-Ray

    MedlinePLUS

    ... x-rays. top of page What does the equipment look like? A panoramic x-ray machine consists ... current x-ray images for diagnosis and disease management. The digital format also allows the dentist to ...

  3. The X-ray universe

    NASA Astrophysics Data System (ADS)

    Tucker, Wallace; Giacconi, Riccardo

    This book is a selective and personal history of X-ray astronomy. The X-ray universe is considered along with the sensible world, historical aspects regarding the discovery and utilization of X-rays, the pioneers of X-ray astronomy, the discovery of an X-ray star, the riddle of the X-ray stars, developments leading to the Uhuru (X-ray Explorer) satellite and the study of neutron stars and black holes, the X-ray sky, a telescope for X-rays, the Einstein observatory (HEAO-2), stellar coronas and supernovas, active galaxies and quasars, clusters of galaxies and the missing mass, and the cosmic X-ray background. Attention is also given to NASA's Advanced X-Ray Astrophysics Facility, which will open a permanent window on the X-ray universe.

  4. Investigation of the relationship between linear attenuation coefficients and CT Hounsfield units using radionuclides for SPECT

    Microsoft Academic Search

    Saxby Brown; Dale L. Bailey; Kathy Willowson; Clive Baldock

    2008-01-01

    This study has investigated the relationship between linear attenuation coefficients (?) and Hounsfield units (HUs) for six materials covering the range of values found clinically. Narrow-beam ? values were measured by performing radionuclide transmission scans using 99mTc, 123I, 131I, 201Tl and 111In. The ? values were compared to published data. The relationships between ? and HU were determined. These relationships

  5. Diffuse attenuation coefficient of downwelling irradiance: An evaluation of remote sensing methods

    Microsoft Academic Search

    Zhong-Ping Lee; Miroslaw Darecki; Kendall L. Carder; Curtiss O. Davis; Dariusz Stramski; W. Joseph Rhea

    2005-01-01

    The propagation of downwelling irradiance at wavelength ? from surface to a depth (z) in the ocean is governed by the diffuse attenuation coefficient, $\\\\bar{K}_{d}$(?). There are two standard methods for the derivation of $\\\\bar{K}_{d}$(?) in remote sensing, which both are based on empirical relationships involving the blue-to-green ratio of ocean color. Recently, a semianalytical method to derive $\\\\bar{K}_{d}$(?) from

  6. X rays in medicine

    SciTech Connect

    Hendee, W.R. [Medical College of Wisconsin, Milwaukee, Wisconsin (United States)

    1995-11-01

    For almost a century, x rays have been used for medical imaging and for radiation therapy. Now these two clinical regimes are converging in the latest technology. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.

  7. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    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)

  8. X-Ray Diffraction

    NSDL National Science Digital Library

    Matter.org

    This site from the University of London presents a tutorial on several methods of X-ray diffraction, including the powder, rotating crystal, and Laue methods Each section includes interactive Java applets, exercises, and links to a glossary of terms.

  9. Total mass attenuation coefficient evaluation of ten materials commonly used to simulate human tissue

    NASA Astrophysics Data System (ADS)

    Ferreira, C. C.; Ximenes, R. E.; Garcia, C. A. B.; Vieira, J. W.; Maia, A. F.

    2010-11-01

    To study the doses received by patient submitted to ionizing radiation, several materials are used to simulate the human tissue and organs. The total mass attenuation coefficient is a reasonable way for evaluating the usage in dosimetry of these materials. The total mass attenuation coefficient is determined by photon energy and constituent elements of the material. Currently, the human phantoms are composed by a unique material that presents characteristics similar to the mean proprieties of the different tissues within the region. Therefore, the phantoms are usually homogeneous and filled with a material similar to soft tissue. We studied ten materials used as soft tissue-simulating. These materials were named: bolus, nylon®, orange articulation wax, red articulation wax, PMMA, modelling clay, bee wax, paraffin 1, paraffin 2 and pitch. The objective of this study was to verify the best material to simulate the human cerebral tissue. We determined the elementary composition, mass density and, therefore, calculated the total mass attenuation coefficient of each material. The results were compared to the values established by the International Commission on Radiation Units and Measurements - ICRU, report n° 44, and by the International Commission on Radiation Protection - ICRP, report n° 89, to determine the best material for this energy interval. These results indicate that new head phantoms can be constructed with nylon®.

  10. Phase contrast imaging using a micro focus x-ray source

    NASA Astrophysics Data System (ADS)

    Zhou, Wei; Majidi, Keivan; Brankov, Jovan G.

    2014-09-01

    Phase contrast x-ray imaging, a new technique to increase the imaging contrast for the tissues with close attenuation coefficients, has been studied since mid 1990s. This technique reveals the possibility to show the clear details of the soft tissues and tumors in small scale resolution. A compact and low cost phase contrast imaging system using a conventional x-ray source is described in this paper. Using the conventional x-ray source is of great importance, because it provides the possibility to use the method in hospitals and clinical offices. Simple materials and components are used in the setup to keep the cost in a reasonable and affordable range.Tungsten K?1 line with the photon energy 59.3 keV was used for imaging. Some of the system design details are discussed. The method that was used to stabilize the system is introduced. A chicken thigh bone tissue sample was used for imaging followed by the image quality, image acquisition time and the potential clinical application discussion. High energy x-ray beam can be used in phase contrast imaging. Therefore the radiation dose to the patients can be greatly decreased compared to the traditional x-ray radiography.

  11. Comparison of photon attenuation coefficients (2-150 KeV) for diagnostic imaging simulations

    NASA Astrophysics Data System (ADS)

    Dodge, Charles W., III; Flynn, Michael J.

    2004-05-01

    The Radiology Research Laboratory at the Henry Ford Hospital has been involved in modeling x-ray units in order to predict image quality. A critical part of that modeling process is the accurate choice of interaction coefficients. This paper serves as a review and comparison of existing interaction models. Our objective was to obtain accurate and easily calculated interaction coefficients, at diagnostically relevant energies. We obtained data from: McMaster, Lawrence Berkeley Lab data (LBL), XCOM and FFAST Data from NIST, and the EPDL-97 database via LLNL. Our studies involve low energy photons; therefore, comparisons were limited to Coherent (Rayleigh), Incoherent (Compton) and Photoelectric effects, which were summed to determine a total interaction cross section. Without measured data, it becomes difficult to definitively choose the most accurate method. However, known limitations in the McMaster data and smoothing of photo-edge transitions can be used as a guide to establish more valid approaches. Each method was compared to one another graphically and at individual points. We found that agreement between all methods was excellent when away from photo-edges. Near photo-edges and at low energies, most methods were less accurate. Only the Chanter (FFAST) data seems to have consistently and accurately predicted the placement of edges (through M-shell), while minimizing smoothing errors. The EPDL-97 data by LLNL was the best over method in predicting coherent and incoherent cross sections.

  12. X-ray radiography for container inspection

    DOEpatents

    Katz, Jonathan I. (Clayton, MO); Morris, Christopher L. (Los Alamos, NM)

    2011-06-07

    Arrangements of X-ray inspection systems are described for inspecting high-z materials in voluminous objects such as containers. Inspection methods may involve generating a radiographic image based on detected attenuation corresponding to a pulsed beams of radiation transmitted through a voluminous object. The pulsed beams of radiation are generated by a high-energy source and transmitted substantially downward along an incident angle, of approximately 1.degree. to 30.degree., to a vertical axis extending through the voluminous object. The generated radiographic image may be analyzed to detect on localized high attenuation representative of high-z materials and to discriminate high-z materials from lower and intermediate-z materials on the basis of the high density and greater attenuation of high-z material for higher energy (3-10 MeV) X-rays, and the compact nature of threatening masses of fissionable materials.

  13. Simultaneous reconstruction of emission activity and attenuation coefficient distribution from TOF data, acquired with external transmission source.

    PubMed

    Panin, V Y; Aykac, M; Casey, M E

    2013-06-01

    The simultaneous PET data reconstruction of emission activity and attenuation coefficient distribution is presented, where the attenuation image is constrained by exploiting an external transmission source. Data are acquired in time-of-flight (TOF) mode, allowing in principle for separation of emission and transmission data. Nevertheless, here all data are reconstructed at once, eliminating the need to trace the position of the transmission source in sinogram space. Contamination of emission data by the transmission source and vice versa is naturally modeled. Attenuated emission activity data also provide additional information about object attenuation coefficient values. The algorithm alternates between attenuation and emission activity image updates. We also proposed a method of estimation of spatial scatter distribution from the transmission source by incorporating knowledge about the expected range of attenuation map values. The reconstruction of experimental data from the Siemens mCT scanner suggests that simultaneous reconstruction improves attenuation map image quality, as compared to when data are separated. In the presented example, the attenuation map image noise was reduced and non-uniformity artifacts that occurred due to scatter estimation were suppressed. On the other hand, the use of transmission data stabilizes attenuation coefficient distribution reconstruction from TOF emission data alone. The example of improving emission images by refining a CT-based patient attenuation map is presented, revealing potential benefits of simultaneous CT and PET data reconstruction. PMID:23648397

  14. Journal of X-Ray Science and Technology 20 (2012) 199211 199 DOI 10.3233/XST-2012-0329

    E-print Network

    Wang, Ge

    2012-01-01

    , PCA 1. Introduction In a conventional x-ray computed tomography (CT) system, the x-ray source hasJournal of X-Ray Science and Technology 20 (2012) 199­211 199 DOI 10.3233/XST-2012-0329 IOS Press to the energy fluence integrated over the entire incidence spectrum. Given that x-ray attenuation is dependent

  15. Lumbosacral spine x-ray

    MedlinePLUS

    X-ray - lumbosacral spine; X-ray - lower spine ... be placed over the lower part of your spine. You will be asked to hold your breath ... x-ray. The most common reason for lumbosacral spine x-ray is to look for the cause ...

  16. Calculation of radiation attenuation coefficients in Portland cements mixed with silica fume, blast furnace slag and natural zeolite

    Microsoft Academic Search

    ?brahim Türkmen; Yüksel Özdemir; Murat Kurudirek; Faruk Demir; Önder Simsek; Ramazan Demirbo?a

    2008-01-01

    This paper presents the radiation attenuation coefficients expressed as mass attenuation coefficients for Portland cement, zeolite, blast furnace slag, silica fume and their mixed types in function of the Photon energy over the energy range of 1keV to 2MeV. It was observed that different percentages of constituents in cement and cement mixed with different additives such as zeolite, silica fume

  17. X-ray astronomical spectroscopy

    NASA Technical Reports Server (NTRS)

    Holt, Stephen S.

    1987-01-01

    The contributions of the Goddard group to the history of X-ray astronomy are numerous and varied. One role that the group has continued to play involves the pursuit of techniques for the measurement and interpretation of the X-ray spectra of cosmic sources. The latest development is the selection of the X-ray microcalorimeter for the Advanced X-ray Astrophysics Facility (AXAF) study payload. This technology is likely to revolutionize the study of cosmic X-ray spectra.

  18. X-ray Crystallography

    NSDL National Science Digital Library

    In this activity, by the Concord Consortium's Molecular Literacy project, students are introduced to the fundamental principles of X-ray crystallography and "guides students through a series of activities for learning how structural information can be derived from X-ray diffraction patterns." Upon completion of this activity students should be able to describe what can be detected with X-ray crystallography (proteins in particular) and explain the impact of temperature, atom size, and impurities in the test. The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In the activity, students are allowed to explore at their own pace in a digital environment full of demonstrations, illustrations, and models they can manipulate. In addition to the activity, visitors will find an overview of the activity, a test and rubric, central concepts, and their correlation to AAAS standards.

  19. X-ray laser driven gold targets

    NASA Astrophysics Data System (ADS)

    Petrova, Tz. B.; Whitney, K. G.; Davis, J.

    2014-03-01

    The femtosecond population dynamics of gold irradiated by a coherent high-intensity (>1017 W/cm2) x-ray laser pulse is investigated theoretically. There are two aspects to the assembled model. One is the construction of a detailed model of platinum-like gold inclusive of all inner-shell states that are created by photoionization of atomic gold and decay either by radiative or Auger processes. Second is the computation of the population dynamics that ensues when an x-ray pulse is absorbed in gold. The hole state generation depends on the intensity and wavelength of the driving x-ray pulse. The excited state populations reached during a few femtosecond timescales are high enough to generate population inversions, whose gain coefficients are calculated. These amplified lines in the emitted x-ray spectrum provide important diagnostics of the radiation dynamics and also suggest a nonlinear way to increase the frequency of the coherent output x-ray pulses relative to the frequency of the driver input x-ray pulse.

  20. An Effect of Temperature on X-Ray Absorption

    Microsoft Academic Search

    H. S. Read

    1926-01-01

    The effect of temperature on the average atomic absorption coefficients for x-rays.-The variation with temperature of the absorption by sheets of Al, Cu, Fe, Ni, Ag, and Pb of the total x-radiation from a tungsten x-ray tube operated at 50 kv has been studied. The measurements were made by balancing the ionization currents produced by two x-ray beams from the

  1. Magnetic imaging with soft X-ray microscopy

    Microsoft Academic Search

    Peter Fischer; Greg Denbeaux; Thomas Eimüller; Dagmar Goll; Gisela Schütz

    2002-01-01

    Recent achievements in magnetic transmission soft X-ray microscopy are reviewed. The magnetic contrast is given by X-ray magnetic circular dichroism, i.e., the dependence of the absorption coefficient of circularly polarized X-rays on the projection of the magnetization in a ferromagnetic system onto the photon propagation direction. A lateral resolution down at 25 nm is provided by Fresnel zone plates used

  2. X-ray microtomography

    SciTech Connect

    Landis, Eric N., E-mail: landis@maine.edu [Department of Civil and Environmental Engineering, University of Maine, 5711 Boardman Hall, Orono, Maine 04469 (United States); Keane, Denis T., E-mail: dtkeane@northwestern.edu [Department of Materials Science and Engineering, Northwestern University (United States); DND-CAT, Advanced Photon Source, Argonne National Laboratory, Bldg. 432/A002, 9700 S. Cass Ave, Argonne, Illinois 60439 (United States)

    2010-12-15

    In this tutorial, we describe X-ray microtomography as a technique to nondestructively characterize material microstructure in three dimensions at a micron level spatial resolution. While commercially available laboratory scale instrumentation is available, we focus our attention on synchrotron-based systems, where we can exploit a high flux, monochromatic X-ray beam to produce high fidelity three-dimensional images. A brief description of the physics and the mathematical analysis behind the technique is followed by example applications to specific materials characterization problems, with a particular focus on the utilization of three-dimensional image processing that can be used to extract a wide range of useful information.

  3. Electron density and effective atomic number (Zeff) determination through x-ray Moiré deflectometry

    NASA Astrophysics Data System (ADS)

    Valdivia Leiva, Maria Pia; Stutman, Dan; Finkenthal, Michael

    2014-10-01

    Talbot-Lau based Moiré deflectometry is a powerful density diagnostic capable of delivering refraction information and attenuation from a single image, through the accurate detection of X-ray phase-shift and intensity. The technique is able to accurately measure both the real part of the index of refraction ? (directly related to electron density) and the attenuation coefficient ? of an object placed in the x-ray beam. Since the atomic number Z (or Zeff for a composite sample) is proportional to these quantities, an elemental map of the effective atomic number can be obtained with the ratio of the phase and the absorption image. The determination of Zeff from refraction and attenuation measurements with Moiré deflectometry could be of high interest in various fields of HED research such as shocked materials and ICF experiments as Zeff is linked, by definition, to the x-ray absorption properties of a specific material. This work is supported by U.S. DoE/NNSA Grant No. 435 DENA0001835.

  4. Dynamic changes of integrated backscatter, attenuation coefficient and bubble activities during high-intensity focused ultrasound (HIFU) treatment.

    PubMed

    Zhang, Siyuan; Wan, Mingxi; Zhong, Hui; Xu, Cheng; Liao, Zhenzhong; Liu, Huanqing; Wang, Supin

    2009-11-01

    This paper simultaneously investigated the transient characteristics of integrated backscatter (IBS), attenuation coefficient and bubble activities as time traces before, during and after HIFU treatment, with different HIFU parameters (acoustic power and duty cycle) in both transparent tissue-mimicking phantoms and freshly excised bovine livers. These dynamic changes of acoustic parameters and bubble activities were correlated with the visualization of lesion development selected from photos, conventional B-mode ultrasound images and differential IBS images over the whole procedure of HIFU treatment. Two-dimensional radiofrequency (RF) data were acquired by a modified diagnostic ultrasound scanner to estimate the changes of mean IBS and attenuation coefficient averaged in the lesion region, and to construct the differential IBS images and B-mode ultrasound images simultaneously. Bubble activities over the whole procedure of HIFU treatment were investigated by the passive cavitation detection (PCD) method and the changes in subharmonic and broadband noise were correlated with the transient characteristics of IBS and attenuation coefficient. When HIFU was switched on, IBS and attenuation coefficient increased with the appearance of bubble clouds in the B-mode and differential IBS image. At the same time, the level of subharmonic and broadband noise rose abruptly. Then, there was an initial decrease in the attenuation coefficient, followed by an increase when at lower HIFU power. As the lesion appeared, IBS and attenuation coefficient both increased rapidly to a value twice that of normal. Then the changes in IBS and attenuation coefficient showed more complex patterns, but still showed a slower trend of increases with lesion development. Violent bubble activities were visible in the gel and were evident as strongly echogenic regions in the differential IBS images and B-mode images simultaneously. This was detected by a dramatic high level of subharmonic and broadband noise at the same time. These bubble activities caused fluctuations in IBS and attenuation coefficient during HIFU treatment. After HIFU, IBS and attenuation coefficient decreased gradually accompanied by the fadeout of bright hyperechoic spot in the B-mode and differential IBS image, but were still higher than normal when they were stable. The increases of IBS and attenuation coefficient were greater when using higher acoustic power or a higher duty cycle of the therapeutic emission. These experiments indicated that the bubble activities had the dominant effects on the transient characteristics of IBS and attenuation. This should be taken into consideration when using the dynamic acoustic-property changes for the potentially real-time monitoring imaging of HIFU treatment. PMID:19716225

  5. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV

    NASA Astrophysics Data System (ADS)

    Buhr, H.; Büermann, L.; Gerlach, M.; Krumrey, M.; Rabus, H.

    2012-12-01

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given.

  6. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV.

    PubMed

    Buhr, H; Büermann, L; Gerlach, M; Krumrey, M; Rabus, H

    2012-12-21

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given. PMID:23192280

  7. Atomic Number and Electron Density Measurement Using a Conventional X-ray Tube and a CdTe Detector

    NASA Astrophysics Data System (ADS)

    Zou, Wenjuan; Nakashima, Takuya; Onishi, Yoshiaki; Koike, Akifumi; Shinomiya, Bunji; Morii, Hisashi; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

    2008-09-01

    In order to apply the dual-energy technique to material identification, a new computed tomography scanning system was proposed using a conventional X-ray tube and a CdTe detector. This system can provide information of projection data at two distinct energy bands for scanned materials. After introducing an approximation, the measured projection data were reconstructed to obtain the distributions of the X-ray linear attenuation coefficients of the materials at two different energies. Then, the corresponding atomic number and electron density can be derived with the dual-energy X-ray computed tomography (DXCT) method adopted. By comparing the obtained results with theoretical ones, the feasibility of using this system for identifying low-Z materials was demonstrated in this study.

  8. X-ray lithography using holographic images

    DOEpatents

    Howells, M.S.; Jacobsen, C.

    1997-03-18

    Methods for forming X-ray images having 0.25 {micro}m minimum line widths on X-ray sensitive material are presented. A holographic image of a desired circuit pattern is projected onto a wafer or other image-receiving substrate to allow recording of the desired image in photoresist material. In one embodiment, the method uses on-axis transmission and provides a high flux X-ray source having modest monochromaticity and coherence requirements. A layer of light-sensitive photoresist material on a wafer with a selected surface is provided to receive the image(s). The hologram has variable optical thickness and variable associated optical phase angle and amplitude attenuation for transmission of the X-rays. A second embodiment uses off-axis holography. The wafer receives the holographic image by grazing incidence reflection from a hologram printed on a flat metal or other highly reflecting surface or substrate. In this second embodiment, an X-ray beam with a high degree of monochromaticity and spatial coherence is required. 15 figs.

  9. X-ray lithography using holographic images

    DOEpatents

    Howells, Malcolm S. (Berkeley, CA); Jacobsen, Chris (Sound Beach, NY)

    1997-01-01

    Methods for forming X-ray images having 0.25 .mu.m minimum line widths on X-ray sensitive material are presented. A holgraphic image of a desired circuit pattern is projected onto a wafer or other image-receiving substrate to allow recording of the desired image in photoresist material. In one embodiment, the method uses on-axis transmission and provides a high flux X-ray source having modest monochromaticity and coherence requirements. A layer of light-sensitive photoresist material on a wafer with a selected surface is provided to receive the image(s). The hologram has variable optical thickness and variable associated optical phase angle and amplitude attenuation for transmission of the X-rays. A second embodiment uses off-axis holography. The wafer receives the holographic image by grazing incidence reflection from a hologram printed on a flat metal or other highly reflecting surface or substrate. In this second embodiment, an X-ray beam with a high degree of monochromaticity and spatial coherence is required.

  10. X-Ray Spacing

    NSDL National Science Digital Library

    David Barthelmy

    This site features a collection of single-phase X-ray powder diffraction patterns for the three most intense D values of an extensive list of minerals. The information is presented in the form of tables of interplanar spacings (D), relative intensities, hkl plane. There are also links to more information about each mineral, such as chemical formula, composition, environment, and name origin.

  11. Studies on mass attenuation coefficient, effective atomic number and electron density of some thermoluminescent dosimetric compounds

    NASA Astrophysics Data System (ADS)

    Önder, P.; Tur?ucu, A.; Demir, D.; Gürol, A.

    2012-12-01

    Mass attenuation coefficient, ?m , effective atomic number, Zeff, and effective electron density, Nel, were determined experimentally and theoretically for some thermoluminescent dosimetric (TLD) compounds such as MgSO4, CdSO4, Al2O3, Mg2SiO4, ZnSO4, CaSO4, CaF2, NaSO4, Na4P2O7, Ca5F(PO4)3, SiO2, CaCO3 and BaSO4 at 8.04, 8.91, 13.37, 14.97, 17.44, 19.63, 22.10, 24.90, 30.82, 32.06, 35.40, 36.39, 37.26, 43.74, 44.48, 50.38, 51.70, 53.16, 80.99, 276.40, 302.85, 356.01, 383.85 and 661.66 keV photon energies by using an HPGe detector with a resolution of 182 eV at 5.9 keV. The theoretical mass attenuation coefficients were estimated using mixture rule. The calculated values were compared with the experimental values for all compounds. Good agreement has been observed between experimental and theoretical values within experimental uncertainties.

  12. Measurements of mass attenuation coefficient, effective atomic number and electron density of some amino acids

    NASA Astrophysics Data System (ADS)

    Kore, Prashant S.; Pawar, Pravina P.

    2014-05-01

    The mass attenuation coefficients of some amino acids, such as DL-aspartic acid-LR(C4H7NO4), L-glutamine (C4H10N2O3), creatine monohydrate LR(C4H9N3O2H2O), creatinine hydrochloride (C4H7N3O·HCl) L-asparagine monohydrate(C4H9N3O2H2O), L-methionine LR(C5H11NO2S), were measured at 122, 356, 511, 662, 1170, 1275 and 1330 keV photon energies using a well-collimated narrow beam good geometry set-up. The gamma-rays were detected using NaI (Tl) scintillation detection system with a resolution of 0.101785 at 662 keV. The attenuation coefficient data were then used to obtain the effective atomic numbers (Zeff), and effective electron densities (Neff) of amino acids. It was observed that the effective atomic number (Zeff) and effective electron densities (Neff) initially decrease and tend to be almost constant as a function of gamma-ray energy. Zeff and Neff experimental values showed good agreement with the theoretical values with less than 1% error for amino acids.

  13. Dimensionality and noise in energy selective x-ray imaging

    PubMed Central

    Alvarez, Robert E.

    2013-01-01

    Purpose: To develop and test a method to quantify the effect of dimensionality on the noise in energy selective x-ray imaging. Methods: The Cramèr-Rao lower bound (CRLB), a universal lower limit of the covariance of any unbiased estimator, is used to quantify the noise. It is shown that increasing dimensionality always increases, or at best leaves the same, the variance. An analytic formula for the increase in variance in an energy selective x-ray system is derived. The formula is used to gain insight into the dependence of the increase in variance on the properties of the additional basis functions, the measurement noise covariance, and the source spectrum. The formula is also used with computer simulations to quantify the dependence of the additional variance on these factors. Simulated images of an object with three materials are used to demonstrate the trade-off of increased information with dimensionality and noise. The images are computed from energy selective data with a maximum likelihood estimator. Results: The increase in variance depends most importantly on the dimension and on the properties of the additional basis functions. With the attenuation coefficients of cortical bone, soft tissue, and adipose tissue as the basis functions, the increase in variance of the bone component from two to three dimensions is 1.4 × 103. With the soft tissue component, it is 2.7 × 104. If the attenuation coefficient of a high atomic number contrast agent is used as the third basis function, there is only a slight increase in the variance from two to three basis functions, 1.03 and 7.4 for the bone and soft tissue components, respectively. The changes in spectrum shape with beam hardening also have a substantial effect. They increase the variance by a factor of approximately 200 for the bone component and 220 for the soft tissue component as the soft tissue object thickness increases from 1 to 30 cm. Decreasing the energy resolution of the detectors increases the variance of the bone component markedly with three dimension processing, approximately a factor of 25 as the resolution decreases from 100 to 3 bins. The increase with two dimension processing for adipose tissue is a factor of two and with the contrast agent as the third material for two or three dimensions is also a factor of two for both components. The simulated images show that a maximum likelihood estimator can be used to process energy selective x-ray data to produce images with noise close to the CRLB. Conclusions: The method presented can be used to compute the effects of the object attenuation coefficients and the x-ray system properties on the relationship of dimensionality and noise in energy selective x-ray imaging systems. PMID:24320442

  14. An examination of mass thickness measurements with X-ray sources

    Microsoft Academic Search

    Chen Mincong; Li Hongmei; Chen Ziyu; Shen Ji

    2008-01-01

    A method using X-rays to measure mass thickness is discussed. The method utilizes a filter to absorb low energy and characteristic photons so that the hardened X-ray spectra have a peaked energy distribution. An equivalent X-ray energy, which defines the attenuation in a material of interest can be used. The effect on the X-ray spectra of different filters is examined

  15. X-ray lithography masking

    NASA Technical Reports Server (NTRS)

    Smith, Henry I. (Inventor); Lim, Michael (Inventor); Carter, James (Inventor); Schattenburg, Mark (Inventor)

    1998-01-01

    X-ray masking apparatus includes a frame having a supporting rim surrounding an x-ray transparent region, a thin membrane of hard inorganic x-ray transparent material attached at its periphery to the supporting rim covering the x-ray transparent region and a layer of x-ray opaque material on the thin membrane inside the x-ray transparent region arranged in a pattern to selectively transmit x-ray energy entering the x-ray transparent region through the membrane to a predetermined image plane separated from the layer by the thin membrane. A method of making the masking apparatus includes depositing back and front layers of hard inorganic x-ray transparent material on front and back surfaces of a substrate, depositing back and front layers of reinforcing material on the back and front layers, respectively, of the hard inorganic x-ray transparent material, removing the material including at least a portion of the substrate and the back layers of an inside region adjacent to the front layer of hard inorganic x-ray transparent material, removing a portion of the front layer of reinforcing material opposite the inside region to expose the surface of the front layer of hard inorganic x-ray transparent material separated from the inside region by the latter front layer, and depositing a layer of x-ray opaque material on the surface of the latter front layer adjacent to the inside region.

  16. Fluctuation X-Ray Scattering

    SciTech Connect

    Saldin, PI: D. K.; Co-I's: J. C. H. Spence and P. Fromme

    2013-01-25

    The work supported by the grant was aimed at developing novel methods of finding the structures of biomolecules using x-rays from novel sources such as the x-ray free electron laser and modern synchrotrons

  17. Encapsulating X-Ray Detectors

    NASA Technical Reports Server (NTRS)

    Conley, Joseph M.; Bradley, James G.

    1987-01-01

    Vapor-deposited polymer shields crystals from environment while allowing X rays to pass. Polymer coating transparental to X rays applied to mercuric iodide detector in partial vacuum. Coating protects crystal from sublimation, chemical attack, and electrical degradation.

  18. X-Rays for Children

    MedlinePLUS

    ... Orthodontic X-rays (also called cephalometric or lateral skull) — This type of X-ray shows the head ... jaws and the relationship of bones in the skull. It helps an orthodontist make an accurate diagnosis ...

  19. Beam hardening in X-ray reconstructive tomography

    Microsoft Academic Search

    R A Brooks; G Di Chiro

    1976-01-01

    As a polychromatic X-ray beam passes through matter, low energy photons are preferentially absorbed, and the (logarithmic) attenuation is no longer a linear function of absorber thickness. This leads to various artifacts in reconstructive tomography. If a water bag is used, the nonlinear attenuation in bone causes a distortion of the bone values and a spill-over inside the skull, or

  20. Bone X-Ray (Radiography)

    MedlinePLUS

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

  1. A confocal three-dimensional micro X-ray scattering technology based on Rayleigh to Compton ratio for identifying materials with similar density and different weight percentages of low-Z elements

    NASA Astrophysics Data System (ADS)

    Li, Fangzuo; Liu, Zhiguo; Sun, Tianxi; Yang, Chaolin; Sun, Xuepeng; Sun, Weiyuan; He, Jialin; Ding, Xunliang

    2015-07-01

    A point-by-point Rayleigh to Compton scattering ratio (R/C) imaging for two polymer materials with similar density and different weight percentages of low-Z elements was carried out by using the confocal three-dimensional (3D) micro X-ray scatter tomographic technology based on polycapillary X-ray optics. This confocal 3D micro X-ray scatter tomographic technique was based on the confocal configuration of a polycapillary focusing X-ray lens (PFXRL) in the excitation channel and a polycapillary parallel X-ray lens (PPXRL) in the detection channel, which let only the X-rays scattered from the confocal micro-volume overlapped by the input focal spot of the PPXRL and the output focal spot of the PFXRL be detected by the detector. The main scope of this study was using the confocal 3D micro X-ray scattering tomography based on the R/C ratio to characterize and identify materials with nearly equal low density and different weight percentages of low-Z elements, as other radiological techniques are difficult to discriminate them for their very close attenuation coefficients ? . A mapping of R/C ratios for two thermoplastic polymer materials was obtained, which provided the spatially resolved distribution of their effective atom numbers, and their differences were accordingly presented. This confocal 3D micro X-ray scatter tomographic technique has potential applications in fields such as material identification, dosimetry, medical imaging, carbonation cancer, and so on.

  2. Dependence of optical attenuation coefficient and mechanical tension of irradiated human cartilage measured by optical coherence tomography.

    PubMed

    Martinho Junior, A C; Freitas, A Z; Raele, M P; Santin, S P; Soares, F A N; Herson, M R; Mathor, M B

    2015-03-01

    As banked human tissues are not widely available, the development of new non-destructive and contactless techniques to evaluate the quality of allografts before distribution for transplantation is very important. Also, tissues will be processed accordingly to standard procedures and to minimize disease transmission most tissue banks will include a decontamination or sterilization step such as ionizing radiation. In this work, we present a new method to evaluate the internal structure of frozen or glycerol-processed human cartilages, submitted to various dosis of irradiation, using the total optical attenuation coefficient retrieved from optical coherence tomography (OCT) images. Our results show a close relationship between tensile properties and the total optical attenuation coefficient of cartilages. Therefore, OCT associated with the total optical attenuation coefficient open a new window to evaluate quantitatively biological changes in processed tissues. PMID:24322969

  3. Dependence of optical attenuation coefficient and mechanical tension of irradiated human cartilage measured by optical coherence tomography.

    PubMed

    Martinho, A C; Freitas, A Z; Raele, M P; Santin, S P; Soares, F A N; Herson, M R; Mathor, M B

    2014-09-01

    As banked human tissues are not widely available, the development of new non-destructive and contactless techniques to evaluate the quality of allografts before distribution for transplantation is very important. Also, tissues will be processed accordingly to standard procedures and to minimize disease transmission most tissue banks will include a decontamination or sterilization step such as ionizing radiation. In this work, we present a new method to evaluate the internal structure of frozen or glycerol processed human cartilages, submitted to various dosis of irradiation, using the total optical attenuation coefficient retrieved from optical coherence tomography (OCT) images. Our results show a close relationship between tensile properties and the total optical attenuation coefficient of cartilages. Therefore, OCT associated with the total optical attenuation coefficient open a new window to evaluate quantitatively biological changes in processed tissues. PMID:23887800

  4. Jovian X-ray emissions

    NASA Technical Reports Server (NTRS)

    Waite, J. H.; Lewis, W. S.; Gladstone, G. R.; Fabian, A. C.; Brandt, W. N.

    1996-01-01

    The Einstein and Rosat observations of X-ray emissions from Jupiter are summarized. Jupiter's soft X-ray emission is observed to originate from the planet's auroral zones, and specifically, from its equatorial region. The processes responsible for these emissions are not established. The brightness distribution of the Jovian X-rays is characterized by the dependence on central meridian longitude and by north-south and morning-afternoon asymmetries. The X-rays observed during the impact of the comet Shoemaker-Levy 9 are believed to be impact-induced brightenings of the X-ray aurora.

  5. X-ray spectra and quality parameters from Monte Carlo simulation and analytical filters.

    PubMed

    Salehi, Z; Ya Ali, N K; Yusoff, A L

    2012-11-01

    BEAMnrc was used to derive the X-ray spectra, from which HVL and homogeneity coefficient were determined, for different kVp and filtration settings. Except for the peak at 61 keV, the spectra are in good agreement with the IPEM report 78 data for the case of filtered beams, whereas the unfiltered beams exhibit softer spectra. Although the current attenuation data deviates from the IPEM 78 data by ~±0.5%, this has negligible effects on the calculated HVL values. PMID:22940409

  6. Soft X-ray shock loading and momentum coupling in meteorite and planetary materials

    NASA Astrophysics Data System (ADS)

    Remo, J. L.; Furnish, M. D.; Lawrence, R. J.

    2012-03-01

    X-ray momentum coupling coefficients, CM, were determined by measuring stress waveforms in planetary materials subjected to impulsive radiation loading from the SNL Z-machine. Targets were prepared from iron and stone meteorites, dunite (primarily magnesium rich olivine) in solid and powder forms (~5 - 300 ?m grains), and Si, Al, and Fe. All samples were ~1 mm thick and, except for Si, backed by LiF single-crystal windows. The spectra of the incident x-rays included thermal radiation (blackbody 170 - 237 eV) and line emissions from the pinch material (Cu, Ni, Al, or stainless steel). Target fluences of 0.4 - 1.7 kJ/cm2 at intensities 43 - 260 GW/cm2 produced front surface plasma pressures of 2.6 - 12.4 GPa. Stress waves driven into the samples were attenuating due to the short ~5 ns duration of the drive pulse. CM was determined using the fact that an attenuating wave impulse is constant, and accounted for the mechanical impedance mismatch between samples and window. Values ranged from 0.8 - 3.1 x 10-5 s/m. CTH hydrocode modeling of x-ray coupling to porous and fully dense silica corroborated experimental results and extrapolations to other materials.

  7. The effect of scintillator response on signal difference to noise ratio in X-ray medical imaging

    NASA Astrophysics Data System (ADS)

    Ninos, K.; Cavouras, D.; Fountos, G.; Kandarakis, I.

    2010-10-01

    The aim of the present study was to examine the effect of scintillator material properties on the signal difference to noise ratio (SdNR) under X-ray imaging conditions. To this aim, SdNR was modelled in terms of scintillator material properties such as the quantum detection efficiency (QDE), the intrinsic energy conversion efficiency (ICE) and the light transmission efficiency (LTE). Scintillators were assumed to be in the form of scintillator layers (phosphor screens) with various thicknesses ranging from 70 to 110 mg/cm2. Data on the X-ray absorption and optical properties of the scintillators were either calculated from tabulated data, i.e. X-ray attenuation coefficients for QDE estimation, or were obtained from previous experimental studies. It was found that in a wide range of X-ray tube voltages the Gd2O2S:Tb scintillator produced higher SdNR values, while the CsI:Tl scintillator was better at lower voltages (below 65 kVp). It was additionally verified that, in the range of X-ray diagnostic energies, SdNR increases with the thickness of the scintillator layer screen. In conclusion, SdNR may be critically affected by scintillator properties and, hence, it may be significantly improved by appropriately selecting the type and thickness of the phosphor screen to be integrated into an imaging system.

  8. Soft x-ray lasers

    SciTech Connect

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

    1988-12-01

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

  9. Binary x-ray pulsars

    SciTech Connect

    Rappaport, S. (Massachusetts Inst. of Tech., Cambridge); Joss, P.C.

    1980-01-01

    Progress made over the last decade in the understanding of the binary x-ray pulsars is reviewed. The characteristics of the pulse profiles of the known binary x-ray pulsars are discussed, and observed variations in pulse period corresponding to the spin-up of the neutron star are considered. Determinations of the orbits and binary system parameters of the binary x-ray pulsars from measurements of pulse arrival times are then examined. Attention is also given to current problems in binary x-ray pulsars, including the apsidal motion test, which allows the determination of the mass distribution within a star, the x-ray source 4U 1626-67, which is believed to be a highly compact binary x-ray source, and the observation of very faint x-ray pulsars with the Einstein Observatory.

  10. X-ray satellite

    NASA Technical Reports Server (NTRS)

    1985-01-01

    An overview of the second quarter 1985 development of the X-ray satellite project is presented. It is shown that the project is proceeding according to plan and that the projected launch date of September 9, 1987 is on schedule. An overview of the work completed and underway on the systems, subsystems, payload, assembly, ground equipment and interfaces is presented. Problem areas shown include cost increases in the area of focal instrumentation, the star sensor light scattering requirements, and postponements in the data transmission subsystems.

  11. Generation of first hard X-ray pulse at Tsinghua Thomson Scattering X-ray Source

    NASA Astrophysics Data System (ADS)

    Du, Yingchao; Yan, Lixin; Hua, Jianfei; Du, Qiang; Zhang, Zhen; Li, Renkai; Qian, Houjun; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

    2013-05-01

    Tsinghua Thomson Scattering X-ray Source (TTX) is the first-of-its-kind dedicated hard X-ray source in China based on the Thomson scattering between a terawatt ultrashort laser and relativistic electron beams. In this paper, we report the experimental generation and characterization of the first hard X-ray pulses (51.7 keV) via head-on collision of an 800 nm laser and 46.7 MeV electron beams. The measured yield is 1.0 × 106 per pulse with an electron bunch charge of 200 pC and laser pulse energy of 300 mJ. The angular intensity distribution and energy spectra of the X-ray pulse are measured with an electron-multiplying charge-coupled device using a CsI scintillator and silicon attenuators. These measurements agree well with theoretical and simulation predictions. An imaging test using the X-ray pulse at the TTX is also presented.

  12. X-ray-illuminated stellar winds - Optically thick wind models for massive X-ray binaries

    NASA Technical Reports Server (NTRS)

    Stevens, Ian R.

    1991-01-01

    The work of Stevens and Kallman (1990) on the effect of accretion-powered X-rays from the neutron star on the dynamics of the line-driven stellar wind of the early-type primary is extended. Radiative force multipliers that now depend on the column of attenuating material, as well as the ionization parameter, are calculated. Optical depth effects are found to suppress the effects of X-ray ionization on the force multipliers. A number of dynamical models for the winds of massive X-ray binary systems (MXRBs) are calculated with these force multipliers. Unlike the optically thin models, self-consistent dynamical solutions are found for reasonable values of the X-ray luminosity. These solutions also reveal the presence of nonlinear mechanisms that affect wind dynamics, whereby relatively small changes in the force multipliers can lead to significant changes in the wind structure. The models find the existence of a self-consistent region of solution at an X-ray luminosity of about 10 to the 36th ergs/s and suggest the possible existence of high-luminosity states.

  13. New large-area x-ray image sensor

    NASA Astrophysics Data System (ADS)

    Ouimette, Donald R.; Nudelman, Sol; Aikens, Richard S.

    1998-07-01

    A new high speed/high resolution X-ray detector called the XEBIT (X-ray sensitive Electron Beam Image Tube) is currently under development at the University of Connecticut Health Center. This large area (9' diameter) direct conversion detector is based on an X-ray photoconductor called thallium bromide. The device utilizes cathode ray tube technology to provide a 30 frame per second raster scanned electron beam to both charge and readout the photoconductor. Thallium bromide is a high Z material with a linear attenuation coefficient of 28.11 cm-1 at 60 kev. This high stopping power results in a quantum efficiency of 57% at 60 kev for 300 micron thick layers. Thallium bromide is a very good X-ray photoconductor that requires 6.5 ev to create an electron-hole pair. For 60 kev photons, this results in a gain 9230 per absorbed photon. With a hole-mobility lifetime product of 1.5 X 10-6 cm2/volt, good charge collection can be achieved at reasonable field strengths. Thallium bromide has a very high band gap of 2.7 ev and a dielectric constant of 33. Its resistivity, which is 5 X 109 ohm-cm at room temperature, is dominated by ionic conductivity. Fortunately, ionic conductivity has a strong temperature dependence that can be significantly reduced with moderate cooling to -25 degrees centigrade. The XEBIT uses thallium bromide as an X- ray photoconductor in a vidicon type image tube. Its principals of operation are very similar to the standard light sensitive vidicon that were utilized extensively in the commercial television industry. A scanning electron beam charges the TlBr surface, with respect to the positively biased front surface, providing the necessary electric field across the photoconductor for charge transport. X-rays then penetrate the window and are absorbed by the thallium bromide. The absorbed photons generate large numbers of electron-hole pairs due to the high conversion gain. Electrons drift under the electric field to the positive bias electrode and the holes drift to the vacuum surface and annihilate stored charge. This results in an image dependent charge pattern on the vacuum surface of the photoconductor. A subsequent scan of the photoconductor generates the capacitively coupled signal by replacing the annihilated electrons. The XEBIT utilizes well-developed display tube technology to provide a very cost effective alternative to image intensifier and screen/film based systems. The XEBIT is currently under development as a replacement for X-ray Image Intensifiers in medical imaging applications. The first devices are 9 inch prototypes designed to be no larger than standard intensifiers. It will replace the image intensifier/optics/video camera with one direct conversion device. The XEBIT suffers from no veiling glare and has far superior contrast resolution with over 50 percent modulation at 5 line pairs per millimeter. The XEBIT is capable of full field imaging as well as under scanning to view smaller regions with higher detail.

  14. Impact of SeaWIFS derived diffuse attenuation coefficients (K d_490) on the dynamics and thermodynamics of OGCM simulations

    NASA Astrophysics Data System (ADS)

    Agarwal, Neeraj; Sharma, Rashmi; Agarwal, Vijay K.

    2006-12-01

    The realism of the impact of penetrative solar radiation, an effect we refer to as biological heating, on the upper ocean thermodynamics has been studied using an Ocean General Circulation Model (OGCM). Daily fields of winds, air temperature, specific humidity, net long-wave and shortwave radiation from NCEP were used to force the model. In the control run (cntl-R), diffuse attenuation coefficient (K d) which signifies the visible radiation penetration is parameterized for clear water condition. In the experimental run (exp-R), attenuation coefficient for blue-green wavelength (K d_490) obtained from SeaWiFS sensor was used to determine the penetrative depth of solar radiation. Use of satellite derived K d_490 alters the upper ocean thermodynamics quite significantly. Model simulated parameters sea surface temperature (SST), current and mixed layer depth (MLD) were found to be sensitive to the choice of diffuse attenuation coefficients that limit the penetration of solar radiation into the ocean. The SST cools and MLD deepens in clear water regions (large attenuation depths) due to heat penetration in deeper layers, while the surface gets heated and MLD shoals in regions of high turbidity (low attenuation depths) due to heat trapping.

  15. Miniature x-ray source

    DOEpatents

    Trebes, James E. (Livermore, CA); Stone, Gary F. (Livermore, CA); Bell, Perry M. (Tracy, CA); Robinson, Ronald B. (Modesto, CA); Chornenky, Victor I. (Minnetonka, MN)

    2002-01-01

    A miniature x-ray source capable of producing broad spectrum x-ray emission over a wide range of x-ray energies. The miniature x-ray source comprises a compact vacuum tube assembly containing a cathode, an anode, a high voltage feedthru for delivering high voltage to the anode, a getter for maintaining high vacuum, a connection for an initial vacuum pump down and crimp-off, and a high voltage connection for attaching a compact high voltage cable to the high voltage feedthru. At least a portion of the vacuum tube wall is highly x-ray transparent and made, for example, from boron nitride. The compact size and potential for remote operation allows the x-ray source, for example, to be placed adjacent to a material sample undergoing analysis or in proximity to the region to be treated for medical applications.

  16. Solar X-ray physics

    SciTech Connect

    Bornmann, P.L. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

    1991-01-01

    Research on solar X-ray phenomena performed by American scientists during 1987-1990 is reviewed. Major topics discussed include solar images observed during quiescent times, the processes observed during solar flares, and the coronal, interplanetary, and terrestrial phenomena associated with solar X-ray flares. Particular attention is given to the hard X-ray emission observed at the start of the flare, the energy transfer to the soft X-ray emitting plasma, the late resolution of the flare as observed in soft X-ray, and the rate of occurrence of solar flares as a function of time and latitude. Pertinent aspects of nonflaring, coronal X-ray emission and stellar flares are also discussed. 175 refs.

  17. In situ measurements of attenuation coefficient for evaluating the hardness of cataract lens by a high frequency ultrasonic needle transducer

    Microsoft Academic Search

    Chih-Chung Huang; Ruimin Chen; Po-Hsiang Tsui; Qifa Zhou; Mark S. Humayun; K. Kirk Shung

    2009-01-01

    A cataract is a clouding of the lens in the eye that affects vision. Phacoemulsification is the mostly common surgical method for treating cataracts, and determining the optimal phacoemulsification energy is dependent on measuring the hardness of the lens. This study explored the use of an ultrasound needle transducer for in situ minimally invasive measurements of ultrasound attenuation coefficient to

  18. Topological X-Rays Revisited

    ERIC Educational Resources Information Center

    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…

  19. X-ray crystal interferometers

    NASA Astrophysics Data System (ADS)

    Lider, V. V.

    2014-11-01

    Various configurations of the X-ray crystal interferometer are reviewed. The interferometer applications considered include metrology, the measurement of fundamental physical constants, the study of weakly absorbing phase objects, time-resolved diagnostics, the determination of hard X-ray beam parameters, and the characterization of structural defects in the context of developing an X-ray Michelson interferometer. The three-crystal Laue interferometer (LLL-interferometer), its design, and the experimental opportunities it offers are given particular attention.

  20. Ancient administrative handwritten documents: X-ray analysis and imaging.

    PubMed

    Albertin, F; Astolfo, A; Stampanoni, M; Peccenini, Eva; Hwu, Y; Kaplan, F; Margaritondo, G

    2015-03-01

    Handwritten characters in administrative antique documents from three centuries have been detected using different synchrotron X-ray imaging techniques. Heavy elements in ancient inks, present even for everyday administrative manuscripts as shown by X-ray fluorescence spectra, produce attenuation contrast. In most cases the image quality is good enough for tomography reconstruction in view of future applications to virtual page-by-page `reading'. When attenuation is too low, differential phase contrast imaging can reveal the characters from refractive index effects. The results are potentially important for new information harvesting strategies, for example from the huge Archivio di Stato collection, objective of the Venice Time Machine project. PMID:25723946

  1. X-ray Absorption Spectroscopy

    SciTech Connect

    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.

  2. X-ray computerized tomography analysis and density estimation using a sediment core from the Challenger Mound area in the Porcupine Seabight, off Western Ireland

    NASA Astrophysics Data System (ADS)

    Tanaka, Akiko; Nakano, Tsukasa; Ikehara, Ken

    2011-02-01

    X-ray computerized tomography (CT) analysis was used to image a half-round core sample of 50 cm long recovered from near Challenger Mound in the Porcupine Seabight, off western Ireland during the Integrated Ocean Drilling Program Expedition 307. This allowed three-dimensional examination of complex shapes of pebbles and ice-rafted debris in sedimentary sequences. X-ray CT analysis was also used for the determination of physical properties; a comparison between bulk density by the mass-volume method and estimated density based on linear attenuation coefficients of X-ray CT images provides insight into a spatially detailed and precise map of density variation in samples through the distribution of CT numbers.

  3. Nanoimaging cells using soft X-ray tomography.

    PubMed

    Parkinson, Dilworth Y; Epperly, Lindsay R; McDermott, Gerry; Le Gros, Mark A; Boudreau, Rosanne M; Larabell, Carolyn A

    2013-01-01

    Soft X-ray microscopy is ideally suited to visualizing and quantifying biological cells. Specimens, including eukaryotic cells, are imaged intact, unstained and fully hydrated, and therefore visualized in a near-native state. The contrast in soft X-ray microscopy is generated by the differential attenuation of X-rays by the molecules in the specimen-water is relatively transmissive to this type of illumination compared to carbon and nitrogen. The attenuation of X-rays by the specimen follows the Beer-Lambert law, and therefore both linear and a quantitative measure of thickness and chemical species present at each point in the cell. In this chapter, we will describe the procedures and computational methods that lead to 50 nm (or better) tomographic reconstructions of cells using soft X-ray microscope data, and the subsequent segmentation and analysis of these volumetric reconstructions. In addition to being a high-fidelity imaging modality, soft X-ray tomography is relatively high-throughput; a complete tomographic data set can be collected in a matter of minutes. This new modality is being applied to imaging cells that range from small prokaryotes to stem cells obtained from mammalian tissues. PMID:23086890

  4. Modeling the vertical distributions of downwelling plane irradiance and diffuse attenuation coefficient in optically deep waters

    NASA Astrophysics Data System (ADS)

    Pan, Xiaoju; Zimmerman, Richard C.

    2010-08-01

    The diffuse attenuation coefficient (Kd) is critical to understand the vertical distribution of underwater downwelling irradiance (Ed). Theoretically Ed is composed of the direct solar beam and the diffuse sky irradiance. Applying the statistical results from Hydrolight radiative transfer simulations, Kd is expressed into a mathematical equation (named as PZ06) integrated from the contribution of direct solar beam and diffuse sky irradiance with the knowledge of sky and water conditions. The percent root mean square errors (RMSE) for the vertical distribution of Ed(z) under various sky and water conditions between PZ06 and Hydrolight results are typically less than 4%. Field observations from the southern Middle Atlantic Bight (SMAB) and global in situ data set (NOMAD) also confirmed the validity of PZ06 in reproducing Kd. PZ06 provides an alternative and improvement to the simpler models (e.g., Gordon, 1989; and Kirk, 1991) and an operational ocean color algorithm, while the latter two kinds of models are valid to limited sky and water conditions. PZ06 can be applied to study Kd from satellite remotely sensed images and seems to improve Kd derivation over current operational ocean color algorithm.

  5. Seasonal variability in the vertical attenuation coefficient at 490 nm (K490) in waters around Puerto Rico and US Virgin Islands.

    E-print Network

    Gilbes, Fernando

    Virgin Islands, MODIS Aqua, ENVI #12;INTRODUCTION The vertical diffuse attenuation coefficient (Kd properties. The vertical diffuse attenuation coefficient (Kd) was evaluated for the waters around Puerto Rico and the US Virgin Islands. The MODIS K490 of Band 3 Level-2 daily images were processed with a resolution

  6. Determination of the total attenuation coefficient for six contact lens materials using the Beer-Lambert law.

    PubMed

    Hull, C C; Crofts, N C

    1996-03-01

    The Beer-Lambert law has been used to determine the total attenuation coefficient, mu t, of three hard and three soft contact lens materials. The three hard contact lens materials were PMMA, Polycon II and Boston IV whereas the 3 soft materials were chosen with differing water contents of 38, 55 and 70%, respectively. The total attenuation coefficients of all six materials were obtained from measurements of the axial transmission at 632.8 nm of a series of plano powered lenses varying in axial thickness from 0.5 to 3.5 mm. The value of the total attenuation coefficient depends on both scattering and absorption and hence PMMA and Boston IV, which both incorporated a handling tint, showed significantly higher values (P < 0.0001) of mu t (0.562 +/- 0.010 mm-1 and 0.820 +/- 0.008 mm-1, respectively) than Polycon II (mu t = 0.025 +/- 0.005 mm-1). A comparison between Polycon II and the three hydrated soft contact lens materials showed a significant increase (P < 0.02) in the total attenuation coefficients for the 38% and 55% water content materials, and a weakly significant increase for the 70% water content soft lens material (P < 0.1). On the assumption that the absorption coefficients of these four materials are approximately constant, then this change would be due to an increase in the scattering coefficient of the material and could contribute to an increase in intraocular scatter. No significant difference (P > 0.5) was found between any of the hydrated soft contact lens materials tested. PMID:8762777

  7. Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. XI. N V-VI and F VII-VIII for Ultraviolet and X-Ray Modeling

    NASA Astrophysics Data System (ADS)

    Nahar, Sultana N.

    2006-05-01

    The inverse processes of photoionization and electron-ion recombination for h?+N V<-->N VI+e, h?+N VI<-->N VII+e, h?+F VII<-->F VIII+e, and h?+F VIII<-->F IX+e are studied in detail using a self-consistent unified method for the total electron-ion recombination. The method enables calculation of the total and level-specific recombination rate coefficients ?R and ?R(i), subsuming both radiative and dielectronic recombination (RR and DR). The photoionization and recombination cross sections ?PI and ?RC are computed using an identical wave function expansion for both processes in the close coupling approximation using the R-matrix method. The results include total and partial photoionization cross sections and recombination rate coefficients for all fine-structure levels up to n<=10, about 100 for Li-like N V and F VII with 1/2<=J<=17/2, and over 170 for He-like N VI and F VIII with 0<=J<=10. Level-specific ?PI(nSLJ) and ?R(T nSLJ) are calculated for the first time for these ions. The coupled-channel wave function expansions for N V and F VII consist of 17 levels of cores N VI and F VIII, respectively, and for N VI and F VIII consist of 16 levels of cores N VII and F IX, respectively. Relativistic fine structure is considered through the Breit-Pauli R-matrix method. The single-valued total ?R(T) is presented over an extended temperature range for astrophysical and laboratory plasma applications. Although the total unified ?R(T) for all ions agree well with the available published RR+DR rates, significant differences are noted at the DR peak for N V. Total ?RC(E) and ?R(E) as functions of photoelectron energy are presented for comparison with experiments. Total rates for H-like N VII and F IX are also given for completeness. The cross sections ?PI and ?RC include important atomic effects such as radiation damping, channel couplings, and interference of DR and RR, and should be accurate to within 10%-15%. The comprehensive data sets are applicable for ionization balance and recombination-cascade models for UV and X-ray lines.

  8. X-ray diagnostics for TFTR

    SciTech Connect

    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.

  9. X-ray coherent scattering form factors of tissues, water and plastics using energy dispersion

    NASA Astrophysics Data System (ADS)

    King, B. W.; Landheer, K. A.; Johns, P. C.

    2011-07-01

    A key requirement for the development of the field of medical x-ray scatter imaging is accurate characterization of the differential scattering cross sections of tissues and phantom materials. The coherent x-ray scattering form factors of five tissues (fat, muscle, liver, kidney, and bone) obtained from butcher shops, four plastics (polyethylene, polystyrene, lexan (polycarbonate), nylon), and water have been measured using an energy-dispersive technique. The energy-dispersive technique has several improvements over traditional diffractometer measurements. Most notably, the form factor is measured on an absolute scale with no need for scaling factors. Form factors are reported in terms of the quantity x = ?-1sin (?/2) over the range 0.363-9.25 nm-1. The coherent form factors of muscle, liver, and kidney resemble those of water, while fat has a narrower peak at lower x, and bone is more structured. The linear attenuation coefficients of the ten materials have also been measured over the range 30-110 keV and parameterized using the dual-material approach with the basis functions being the linear attenuation coefficients of polymethylmethacrylate and aluminum.

  10. An explicit formula for the coherent SH waves' attenuation coefficient in random porous materials with low porosities.

    PubMed

    Zhang, Jun; Ye, Wenjing

    2015-09-01

    In this paper, the attenuation coefficient of coherent SH waves in random porous material with uniformly randomly distributed elliptical cavities of different aspect ratios is studied. Based on an analysis of the mechanism for attenuation, a simple macro model for the attenuation coefficient is proposed. The macro model says that the attenuation coefficient can be expressed as a function of the mean scattering cross section and the number density of cavities at low porosities. Then, large-scale numerical simulations using the pre-corrected Fast Fourier Transform (pFFT) algorithm accelerated Boundary Element Method (BEM) are conducted to specify this macro model. Finally, this macro model is compared with four theoretical models derived for composite/porous materials with circular inclusions at the porosity p=3.17% and 5%. Results show this macro model agree well with three of them. Compared to the existing theoretical models, the form of this macro model is simple and has a clear physical meaning. In addition, it is applicable to cases with relatively complex cavities. PMID:25983311

  11. X-ray based extensometry

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  12. X-Ray Exam: Ankle

    MedlinePLUS

    What It Is An ankle X-ray is a safe and painless test that uses a small amount of radiation to make an image of the ankle. ... back part of the foot (tarsal bones). An X-ray machine sends a beam of radiation through ...

  13. X-Ray Diffraction Apparatus

    NASA Technical Reports Server (NTRS)

    Blake, David F. (Inventor); Bryson, Charles (Inventor); Freund, Friedmann (Inventor)

    1996-01-01

    An x-ray diffraction apparatus for use in analyzing the x-ray diffraction pattern of a sample is introduced. The apparatus includes a beam source for generating a collimated x-ray beam having one or more discrete x-ray energies, a holder for holding the sample to be analyzed in the path of the beam, and a charge-coupled device having an array of pixels for detecting, in one or more selected photon energy ranges, x-ray diffraction photons produced by irradiating such a sample with said beam. The CCD is coupled to an output unit which receives input information relating to the energies of photons striking each pixel in the CCD, and constructs the diffraction pattern of photons within a selected energy range striking the CCD.

  14. X-ray shearing interferometer

    DOEpatents

    Koch, Jeffrey A. (Livermore, CA)

    2003-07-08

    An x-ray interferometer for analyzing high density plasmas and optically opaque materials includes a point-like x-ray source for providing a broadband x-ray source. The x-rays are directed through a target material and then are reflected by a high-quality ellipsoidally-bent imaging crystal to a diffraction grating disposed at 1.times. magnification. A spherically-bent imaging crystal is employed when the x-rays that are incident on the crystal surface are normal to that surface. The diffraction grating produces multiple beams which interfere with one another to produce an interference pattern which contains information about the target. A detector is disposed at the position of the image of the target produced by the interfering beams.

  15. The precise measurement of the attenuation coefficients of various IR optical materials applicable to immersion grating

    NASA Astrophysics Data System (ADS)

    Kaji, Sayumi; Sarugaku, Yuki; Ikeda, Yuji; Kobayashi, Naoto; Nakanishi, Kenshi; Kondo, Sohei; Yasui, Chikako; Kawakita, Hideyo

    2014-07-01

    Immersion grating is a next-generation diffraction grating which has the immersed the diffraction surface in an optical material with high refractive index of n > 2, and can provide higher spectral resolution than a classical reflective grating. Our group is developing various immersion gratings from the near- to mid-infrared region (Ikeda et al.1, 2, 3, 4, Sarugaku et al.5, and Sukegawa et al.6). The internal attenuation ?att of the candidate materials is especially very important to achieve the high efficiency immersion gratings used for astronomical applications. Nevertheless, because there are few available data as ?att < 0.01cm-1 in the infrared region, except for measurements of CVD-ZnSe, CVD-ZnS, and single-crystal Si in the short near-infrared region reported by Ikeda et al.7, we cannot select suitable materials as an immersion grating in an aimed wavelength range. Therefore, we measure the attenuation coefficients of CdTe, CdZnTe, Ge, Si, ZnSe, and ZnS that could be applicable to immersion gratings. We used an originally developed optical unit attached to a commercial FTIR which covers the wide wavelength range from 1.3?m to 28?m. This measurement system achieves the high accuracy of (triangle)?att ~ 0.01cm-1. As a result, high-resistivity single-crystal CdZnTe, single-crystal Ge, single-crystal Si, CVD-ZnSe, and CVD-ZnS show ?att < 0.01cm-1 at the wavelength range of 5.5 - 19.0?m, 2.0 - 10.5?m, 1.3 - 5.4?m, 1.7 - 13.2?m, and 1.9 - 9.2?m, respectively. This indicates that these materials are good candidates for high efficiency immersion grating covering those wavelength ranges. We plan to make similar measurement under the cryogenic condition as T <= 10K for the infrared, especially mid-infrared applications.

  16. Aluminum Alloy X-ray Image Classification Using Texture Analysis

    Microsoft Academic Search

    Jun Lu; Qiuqi Ruan

    2006-01-01

    This paper presents an automatic classification approach to the X-ray image classification issue of aluminum alloy by image texture analysis methods. Different from the common processing methods, the texture-based approach (XTexture) treats the X-ray image as a special texture image for further processing. By extracting self-correlation moment and wavelet-coefficient moments as the basic classification features based on image texture analysis,

  17. The Physics Analysis of a Gas Attenuator with Argon as a Working Gas

    SciTech Connect

    Ryutov,, D.D.

    2010-12-07

    A gas attenuator is an important element of the LCLS facility. The attenuator must operate in a broad range of x-ray energies, provide attenuation coefficient between 1 and 10{sup 4} with the accuracy of 1% and, at the same time, be reliable and allow for many months of un-interrupted operation. S. Shen has recently carried out a detailed design study of the attenuator based on the use of nitrogen as a working gas. In this note we assess the features of the attenuator based on the use of argon. We concentrate on the physics issues, not the design features.

  18. Self-detection of x-ray Fresnel transmittivity using photoelectron-induced gas ionization

    E-print Network

    Stoupin, Stanislav

    2015-01-01

    Electric response of an x-ray mirror enclosed in a gas flow ionization chamber was studied under the conditions of total external reflection for hard x-rays. It is shown that the electric response of the system as a function of the incidence angle is defined by x-ray Fresnel transmittivity and photon-electron attenuation properties of the mirror material. A simple interpretation of quantum yield of the system is presented. The approach provides non-invasive in-situ diagnostics of hard x-ray optics, easy access to complementary x-ray transmittivity data in x-ray reflectivity experiments and can also pave the way to novel schemes for angle and energy resolving x-ray detectors.

  19. ImaSim, a software tool for basic education of medical x-ray imaging in radiotherapy and radiology

    NASA Astrophysics Data System (ADS)

    Landry, Guillaume; deBlois, François; Verhaegen, Frank

    2013-11-01

    Introduction: X-ray imaging is an important part of medicine and plays a crucial role in radiotherapy. Education in this field is mostly limited to textbook teaching due to equipment restrictions. A novel simulation tool, ImaSim, for teaching the fundamentals of the x-ray imaging process based on ray-tracing is presented in this work. ImaSim is used interactively via a graphical user interface (GUI). Materials and methods: The software package covers the main x-ray based medical modalities: planar kilo voltage (kV), planar (portal) mega voltage (MV), fan beam computed tomography (CT) and cone beam CT (CBCT) imaging. The user can modify the photon source, object to be imaged and imaging setup with three-dimensional editors. Objects are currently obtained by combining blocks with variable shapes. The imaging of three-dimensional voxelized geometries is currently not implemented, but can be added in a later release. The program follows a ray-tracing approach, ignoring photon scatter in its current implementation. Simulations of a phantom CT scan were generated in ImaSim and were compared to measured data in terms of CT number accuracy. Spatial variations in the photon fluence and mean energy from an x-ray tube caused by the heel effect were estimated from ImaSim and Monte Carlo simulations and compared. Results: In this paper we describe ImaSim and provide two examples of its capabilities. CT numbers were found to agree within 36 Hounsfield Units (HU) for bone, which corresponds to a 2% attenuation coefficient difference. ImaSim reproduced the heel effect reasonably well when compared to Monte Carlo simulations. Discussion: An x-ray imaging simulation tool is made available for teaching and research purposes. ImaSim provides a means to facilitate the teaching of medical x-ray imaging.

  20. Automatic detection of bone fragments in poultry using multi-energy x-rays

    SciTech Connect

    Gleason, Shaun S. (Knoxville, TN); Paulus, Michael J. (Knoxville, TN); Mullens, James A. (Knoxville, TN)

    2002-04-09

    At least two linear arrays of x-ray detectors are placed below a conveyor belt in a poultry processing plant. Multiple-energy x-ray sources illuminate the poultry and are detected by the detectors. Laser profilometry is used to measure the poultry thickness as the x-ray data is acquired. The detector readout is processed in real time to detect the presence of small highly attenuating fragments in the poultry, i.e., bone, metal, and cartilage.

  1. Heavy metallic oxide nanoparticles for enhanced sensitivity in semiconducting polymer x-ray detectors

    Microsoft Academic Search

    A Intaniwet; C A Mills; M Shkunov; P J Sellin; J L Keddie

    2012-01-01

    Semiconducting polymers have previously been used as the transduction material in x-ray dosimeters, but these devices have a rather low detection sensitivity because of the low x-ray attenuation efficiency of the organic active layer. Here, we demonstrate a way to overcome this limitation through the introduction of high density nanoparticles having a high atomic number (Z) to increase the x-ray

  2. Computed tomography and X-ray fluorescence CT of biological samples

    NASA Astrophysics Data System (ADS)

    Pereira, G. R.; Anjos, M. J.; Rocha, H. S.; Faria, P.; Pérez, C. A.; Lopes, R. T.

    2007-10-01

    Transmission microtomography ( ?CT) and X-ray fluorescence microtomography (XRF ?CT) are complementary and noninvasive techniques used for sample characterization. ?CT provide information on the attenuation coefficients, while XRF ?CT can provide the distribution of all elements in a sample. XRF ?CT is a noninvasive technique, based on the detection of X-ray fluorescence emitted by the elements in the sample, and it is used to complement other techniques for sample characterization. The experiments were performed at the X-Ray Fluorescence (XRF) beamline of the Brazilian Synchrotron Light Laboratory (LNLS), Campinas, Brazil. A monochromatic beam of 9.8 keV was used for excitation of the elements within samples and the fluorescence photons were detected by an HPGe detector. The incident beam was monitored by an ionization chamber and a fast scintillator detector was used to detect the transmitted radiation. In this work, several intestine and breast tissue samples were investigated in order to verify the concentration of some elements correlated with the characteristics and pathology of each tissue observed by transmission ?CT. All XRF ?CT were reconstructed using a filtered back-projection algorithm. In those samples the elements Zn, Cu, and Fe were observed.

  3. Laboratory x-ray lasers

    SciTech Connect

    Matthews, D.L.

    1989-08-01

    One of the most innovative spinoffs of ICF technology and physics has been the development of the x-ray wavelength laser. The first incontrovertible demonstration of this type of laser came from LLNL in 1984 using the Novette laser to pump a selenium foil target. The power and energy of Novette were then needed to produce a column of plasma of sufficient length to achieve a sufficient gainlength product ({approximately}5.5, this corresponds to an amplification of {approximately}250X) that could unquestionably illustrate the lasing effect. LLNL ICF expertise was also required to develop time-resolved spectrometers used to view the lasing transitions at {approximately}20 nm, a region of the XUV spectrum normally dominated by high backgrounds. The design of the x-ray laser amplifier, which required maintaining nonequilibrium level populations in a tailored plasma having the proper conditions for gain and x-ray laser beam propagation, was accomplished with modified versions of ICF kinetics and hydrodynamics codes. Since the first demonstration, our progress in the development of the x-ray laser has been rapid. New achievements include production of megawatt power levels at 20 nm, amplified spontaneous emission levels approaching saturation intensity (GL {approximately}17 {at} 20 nm, efficiency (x-ray laser energy/pump energy) {approximately}10{sup {minus}6}), the demonstration of double and triple pass amplification (hinting at the possibility of producing x-ray wavelength resonators), the focusing of x-ray lasers to pump other types of lasers and the first demonstration of an x-ray hologram produced by an x-ray laser. The generation of amplification at ever shorter wavelength is possible using various types of inversion schemes. We depict below this progress benchmarked against production of gain in the water window (2.2 to 4.4 nm,), where applications to biological imaging may be facilitated.

  4. X-Ray photonics: X-rays inspire electron movies

    NASA Astrophysics Data System (ADS)

    Vrakking, Marc J. J.; Elsaesser, Thomas

    2012-10-01

    The advent of high-energy, short-pulse X-ray sources based on free-electron lasers, laser plasmas and high-harmonic generation is now making it possible to probe the dynamics of electrons within molecules.

  5. X-ray fluorescence microtomography analyzing reference samples

    NASA Astrophysics Data System (ADS)

    Pereira, G. R.; Lopes, R. T.; Anjos, M. J.; Rocha, H. S.; Pérez, C. A.

    2007-08-01

    The X-ray fluorescence microtomography (XRFCT) is a non-destructive technique to complement other techniques used for samples characterization. The common techniques provide only information on the attenuation coefficients (transmission microtomography) or electronic density (Compton microtomography) and no information on the distribution of the elements inside of the sample can be obtained in these cases. XRFCT is based on the detection of fluorescence photons emitted by the elements in the sample. As the energy of photons of fluorescence has a particular value for each element, it is possible to obtain the distribution of all the elements in a sample, since that a minimum of fluorescence signal is detected. The experiments were performed at the X-ray fluorescence beamline (D09B-XRF) of the Brazilian Synchrotron Light Source (LNLS), Campinas, Brazil. A monochromatic beam and a white beam was used for the excitation of the elements and the fluorescence photons have been detected by a HPGe detector, placed at 90° to the incident beam. The beam was monitored by an ionization chamber and a fast scintillator detector was used to detect the transmitted radiation. In order to study the performance of the system, some reference samples made of polyethylene filled with standard solutions were analyzed, and some tissues of human breast (normal tissue, benign tumor and malignant tumor) have been analyzed in order to verify the efficiency of the system in determination of the elemental distribution in these kinds of samples. All the tomographic images were reconstructed using a filtered-back projection algorithm. In the breast tissue samples, the elements of higher concentration were Zn, Cu and Fe.

  6. X-Ray Imaging System

    NASA Technical Reports Server (NTRS)

    1986-01-01

    The FluoroScan Imaging System is a high resolution, low radiation device for viewing stationary or moving objects. It resulted from NASA technology developed for x-ray astronomy and Goddard application to a low intensity x-ray imaging scope. FlouroScan Imaging Systems, Inc, (formerly HealthMate, Inc.), a NASA licensee, further refined the FluoroScan System. It is used for examining fractures, placement of catheters, and in veterinary medicine. Its major components include an x-ray generator, scintillator, visible light image intensifier and video display. It is small, light and maneuverable.

  7. X-Ray Diffraction Microscopy

    NASA Astrophysics Data System (ADS)

    Thibault, Pierre; Elser, Veit

    2010-04-01

    X-ray diffraction phenomena have been used for decades to study matter at the nanometer and subnanometer scales. X-ray diffraction microscopy uses the far-field scattering of coherent X-rays to form the 2D or 3D image of a scattering object in a way that resembles crystallography. In this review, we describe the main principles, benefits, and limitations of diffraction microscopy. After sampling some of the milestones of this young technique and its close variants, we conclude with a short assessment of the current state of the field.

  8. The Physics of the Gas Attenuator for the Linac Coherent Light Source (LCLS)

    SciTech Connect

    Ryutov, D.D.; Bionta, R.M.; Hau-Riege, S.P.; Kishiyama, K.I.; McMahon, D.; Roeben, M.D.; Shen, S.; /LLNL, Livermore; Stefan, P.M.; /SLAC; ,

    2011-02-07

    A systematic assessment of a variety of physics issues affecting the performance of the LCLS X-ray beam attenuator is presented. Detailed analysis of the gas flow in the gas attenuator and in the apertures is performed. A lot of attention is directed towards the gas ionization and heating by intense X-ray pulses. The role of these phenomena in possible deviations of the attenuation coefficient from its 'dialed in' value is evaluated and found small in most cases. Other sources of systematic and statistical errors are also discussed. The regimes where the errors may reach a few percent correspond to the lower X-ray energies (less than 2 keV) and highest beam intensities. Other effects discussed include chemical interaction of the gas with apertures, shock formation in the transonic flow in the apertures of the attenuator, generation of electromagnetic wakes in the gas, and head-to-tail variation of the attenuation caused by the ionization of gas or solid. Possible experimental tests of the consistency of the physics assumptions used in the concept of the gas attenuator are discussed. Interaction of X-rays with the solid attenuator (that will be used at higher X-ray energies, from 2.5 to 8 keV) is considered and thermo-mechanical effects caused by the beam heating are evaluated. Wave-front distortions induced by non-uniform heating of both the solid and the gas are found to be small. An overall conclusion drawn from the analysis presented is that the attenuator will be a reliable and highly versatile device, provided that some caution is exercised in its use for highest beam intensities at lowest X-ray energies.

  9. Building X-ray lasers

    NASA Astrophysics Data System (ADS)

    2010-12-01

    The SLAC Linac Coherent Light Source is now the world's brightest source of coherent ångström-wavelength X-rays. Paul Emma, the man who made this achievement possible, spoke to Nature Photonics about the challenges involved.

  10. Miniature x-ray source

    DOEpatents

    Trebes, James E. (Livermore, CA); Bell, Perry M. (Tracy, CA); Robinson, Ronald B. (Modesto, CA)

    2000-01-01

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

  11. X-rays and Cosmology

    E-print Network

    A. C. Fabian

    2000-01-11

    The role of X-ray observations for cosmological studies and conclusions is briefly explored. X-rays currently yield cosmologically interesting results on the abundances, evolution and gas content of clusters of galaxies, on the clustering and evolution of active galaxies and on the X-ray Background. They are unlikely in the long term future to give the most precise values of the cosmological parameters, although in the short term the baryon fraction of clusters and the Sunyaev-Zeldovich effect will remain important determinants and checks for some parameters. X-rays will however continue to play an important role in studying the astrophysics of the formation and growth of black holes, galaxies, groups and clusters. It is possible that this role will be crucial, if winds from active galaxies are responsible for breaking the simple gravitational scaling laws for clusters.

  12. Chiropractic x-ray rationale

    PubMed Central

    Sherman, Ray

    1986-01-01

    The use of x-ray is important to the chiropractic profession. The reasons for this significance are enumerated and discussed. The relevance of roentgenology to present and future chiropractic practice is set forth.

  13. Nanoscale X-ray imaging

    Microsoft Academic Search

    Anne Sakdinawat; David Attwood

    2010-01-01

    Recent years have seen significant progress in the field of soft- and hard-X-ray microscopy, both technically, through developments in source, optics and imaging methodologies, and also scientifically, through a wide range of applications. While an ever-growing community is pursuing the extensive applications of today's available X-ray tools, other groups are investigating improvements in techniques, including new optics, higher spatial resolutions,

  14. X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    1993-05-01

    The primary advantage of the X-ray computed tomography (XRCT) NDE method is that features are not superposed in the image, thereby rendering them easier to interpret than radiographic projection images. Industrial XRCT systems, unlike medical diagnostic systems, have no size and dosage constraints; they are accordingly used for systems from the scale of gas turbine blades, with hundreds-of-kV energies, to those of the scale of ICBMs, requiring MV-level X-ray energies.

  15. X-ray astronomical spectroscopy

    NASA Technical Reports Server (NTRS)

    Holt, S. S.

    1980-01-01

    The current status of the X-ray spectroscopy of celestial X-ray sources, ranging from nearby stars to distant quasars, is reviewed. Particular emphasis is placed on the role of such spectroscopy as a useful and unique tool in the elucidation of the physical parameters of the sources. The spectroscopic analysis of degenerate and nondegenerate stellar systems, galactic clusters and active galactic nuclei, and supernova remnants is discussed.

  16. Improved Algorithms for Accurate Retrieval of UV - Visible Diffuse Attenuation Coefficients in Optically Complex, Inshore Waters

    NASA Technical Reports Server (NTRS)

    Cao, Fang; Fichot, Cedric G.; Hooker, Stanford B.; Miller, William L.

    2014-01-01

    Photochemical processes driven by high-energy ultraviolet radiation (UVR) in inshore, estuarine, and coastal waters play an important role in global bio geochemical cycles and biological systems. A key to modeling photochemical processes in these optically complex waters is an accurate description of the vertical distribution of UVR in the water column which can be obtained using the diffuse attenuation coefficients of down welling irradiance (Kd()). The Sea UV Sea UVc algorithms (Fichot et al., 2008) can accurately retrieve Kd ( 320, 340, 380,412, 443 and 490 nm) in oceanic and coastal waters using multispectral remote sensing reflectances (Rrs(), Sea WiFS bands). However, SeaUVSeaUVc algorithms are currently not optimized for use in optically complex, inshore waters, where they tend to severely underestimate Kd(). Here, a new training data set of optical properties collected in optically complex, inshore waters was used to re-parameterize the published SeaUVSeaUVc algorithms, resulting in improved Kd() retrievals for turbid, estuarine waters. Although the updated SeaUVSeaUVc algorithms perform best in optically complex waters, the published SeaUVSeaUVc models still perform well in most coastal and oceanic waters. Therefore, we propose a composite set of SeaUVSeaUVc algorithms, optimized for Kd() retrieval in almost all marine systems, ranging from oceanic to inshore waters. The composite algorithm set can retrieve Kd from ocean color with good accuracy across this wide range of water types (e.g., within 13 mean relative error for Kd(340)). A validation step using three independent, in situ data sets indicates that the composite SeaUVSeaUVc can generate accurate Kd values from 320 490 nm using satellite imagery on a global scale. Taking advantage of the inherent benefits of our statistical methods, we pooled the validation data with the training set, obtaining an optimized composite model for estimating Kd() in UV wavelengths for almost all marine waters. This optimized composite set of SeaUVSeaUVc algorithms will provide the optical community with improved ability to quantify the role of solar UV radiation in photochemical and photobiological processes in the ocean.

  17. Extragalactic X-ray sources

    SciTech Connect

    Pounds, K.A. (Leicester, University, Leicester, England); Fabian, A.C. (Cambridge University, Cambridge, England)

    1980-01-01

    Surveys of the extragalactic X-ray sky based on data obtained from the Uhuru and Ariel V satellites are considered. The X-ray luminosity function of clusters is discussed the total density of X-ray clusters is found to approach that of all Abell clusters at a luminosity of 10 to the 43rd ergs/sec. It is concluded that for cluster X-ray sources, the bulk of the X-rays below about 10 keV result from thermal bremsstrahlung, predominantly from the cores of the clusters the mass of gas in the core is only a few percent of the total core binding mass, and the X-ray data are consistent with an iron abundance in the hot gas which is about half the cosmic value. Attention is also given to the structure of the nearby rich clusters Perseus, Virgo and Coma, to variability in Seyfert X-radiation and to high-excitation narrow emission line galaxies.

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

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

  19. Cooled window for X-rays or charged particles

    DOEpatents

    Logan, C.M.

    1996-04-16

    A window is disclosed that provides good structural integrity and a very high capacity for removal of the heat deposited by x-rays, electrons, or ions, with minimum attenuation of the desired beam. The window is cooled by providing microchannels therein through which a coolant is pumped. For example, the window may be made of silicon with etched microchannels therein and covered by a silicon member. A window made of silicon with a total thickness of 520 {micro}m transmits 96% of the x-rays at an energy of 60 keV, and the transmission is higher than 90% for higher energy photons. 1 fig.

  20. X-Ray Detector: An x-ray radiation detector design code

    Microsoft Academic Search

    Rick B. Spielman

    1990-01-01

    X-Ray Detector (XRD) is an x-ray detector design code. It is intended to aid in the rapid design of x-ray detector packages. The design capabilities of XRD include filters, x-ray mirrors, x-ray diodes, silicon PIN diodes, GaAs PIN diodes, photoconducting detectors, bolometers, and x-ray film. XRD uses x-ray cross-section information stored in easily-modified external libraries. Interactive calculations are completed in

  1. X-ray Emission from Massive Stars

    E-print Network

    Cohen, David

    X-ray Emission from Massive Stars David Cohen Department of Physics and Astronomy Swarthmore be related to the production of X-rays on massive stars. If so, massive stars' X-rays are much different than those found our own Sun and other cooler stars like the Sun that produce X-rays via magnetic activity

  2. Ultrafast X-ray Sources

    SciTech Connect

    George Neil

    2010-04-19

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

  3. The Discovery of Soft X-ray Loud Broad Absorption Line Quasars

    E-print Network

    Kajal K. Ghosh; Brian Punsly

    2008-01-08

    It is been known for more than a decade that BALQSOs (broad absorption line quasars) are highly attenuated in the X-ray regime compared to other quasars, especially in the soft band ($density ratios that are higher than typical nonBAL radio quiet quasars. Our sample of 3 sources includes one LoBALQSO (low ionization BALQSO) which are generally considered to be the most highly attenuated in the X-rays. The three QSOs are the only known BALQSOs that have X-ray observations that are consistent with no intrinsic soft X-ray absorption. The existence of a large X-ray luminosity and the hard ionizing continuum that it presents to potential UV absorption gas is in conflict with the ionization states that are conducive to line driving forces within BAL winds (especially for the LoBALs).

  4. Dark-field X-ray imaging of unsaturated water transport in porous materials

    SciTech Connect

    Yang, F., E-mail: fei.yang@empa.ch, E-mail: michele.griffa@empa.ch; Di Bella, C.; Lura, P. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600 (Switzerland); Institute for Building Materials (IfB), ETH Zurich, Zürich 8093 (Switzerland); Prade, F.; Herzen, J.; Sarapata, A.; Pfeiffer, F. [Physik-Department and Institut für Medizintechnik, Technische Universität München, Garching (Germany); Griffa, M., E-mail: fei.yang@empa.ch, E-mail: michele.griffa@empa.ch; Jerjen, I. [Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf 8600 (Switzerland)

    2014-10-13

    We introduce in this Letter an approach to X-ray imaging of unsaturated water transport in porous materials based upon the intrinsic X-ray scattering produced by the material microstructural heterogeneity at a length scale below the imaging system spatial resolution. The basic principle for image contrast creation consists in a reduction of such scattering by permeation of the porosity by water. The implementation of the approach is based upon X-ray dark-field imaging via Talbot-Lau interferometry. The proof-of-concept is provided by performing laboratory-scale dark-field X-ray radiography of mortar samples during a water capillary uptake experiment. The results suggest that the proposed approach to visualizing unsaturated water transport in porous materials is complementary to neutron and magnetic resonance imaging and alternative to standard X-ray imaging, the latter requiring the use of contrast agents because based upon X-ray attenuation only.

  5. Broad beam and narrow beam attenuation in Lipowitz's metal

    SciTech Connect

    el-Khatib, E.E.; Podgorsak, E.B.; Pla, C.

    1987-01-01

    Attenuation properties of Lipowitz's metal have been studied for narrow and broad beams of cobalt-60 gamma rays and 4-10 MV x-rays. The measured transmitted fraction for geometries used in radiotherapy depends on the field size and depth of measurement. Therefore a calculation of dose for partially attenuated beams based on narrow beam attenuation coefficients can cause large errors in dosimetry. Our simple calculation of transmitted fractions based on primary attenuation and scattered radiation agrees quite well with the measured data for therapeutic geometries. Also given is a table for linear, mass attenuation, and mass energy absorption coefficients of Lipowitz's metal in the photon energy range from 10 keV to 10 MeV.

  6. Highly porous nanoberyllium for X-ray beam speckle suppression.

    PubMed

    Goikhman, Alexander; Lyatun, Ivan; Ershov, Petr; Snigireva, Irina; Wojda, Pawel; Gorlevsky, Vladimir; Semenov, Alexander; Sheverdyaev, Maksim; Koletskiy, Viktor; Snigirev, Anatoly

    2015-05-01

    This paper reports a special device called a `speckle suppressor', which contains a highly porous nanoberyllium plate squeezed between two beryllium windows. The insertion of the speckle suppressor in an X-ray beam allows manipulation of the spatial coherence length, thus changing the effective source size and removing the undesirable speckle structure in X-ray imaging experiments almost without beam attenuation. The absorption of the nanoberyllium plate is below 1% for 1?mm thickness at 12?keV. The speckle suppressor was tested on the ID06 ESRF beamline with X-rays in the energy range from 9 to 15?keV. It was applied for the transformation of the phase-amplitude contrast to the pure amplitude contrast in full-field microscopy. PMID:25931099

  7. X-ray high-resolution vascular network imaging.

    PubMed

    Plouraboue, F; Cloetens, P; Fonta, C; Steyer, A; Lauwers, F; Marc-Vergnes, J P

    2004-08-01

    This paper presents the first application of high-resolution X-ray synchrotron tomography to the imaging of large microvascular networks in biological tissue samples. This technique offers the opportunity of analysing the full three-dimensional vascular network from the micrometre to the millimetre scale. This paper presents the specific sample preparation method and the X-ray imaging procedure. Either barium or iron was injected as contrast agent in the vascular network. The impact of the composition and concentration of the injected solution on the X-ray synchrotron tomography images has been studied. Two imaging modes, attenuation and phase contrast, are compared. Synchrotron high-resolution computed tomography offers new prospects in the three-dimensional imaging of in situ biological vascular networks. PMID:15315500

  8. Highly porous nanoberyllium for X-ray beam speckle suppression

    PubMed Central

    Goikhman, Alexander; Lyatun, Ivan; Ershov, Petr; Snigireva, Irina; Wojda, Pawel; Gorlevsky, Vladimir; Semenov, Alexander; Sheverdyaev, Maksim; Koletskiy, Viktor; Snigirev, Anatoly

    2015-01-01

    This paper reports a special device called a ‘speckle suppressor’, which contains a highly porous nanoberyllium plate squeezed between two beryllium windows. The insertion of the speckle suppressor in an X-ray beam allows manipulation of the spatial coherence length, thus changing the effective source size and removing the undesirable speckle structure in X-ray imaging experiments almost without beam attenuation. The absorption of the nanoberyllium plate is below 1% for 1?mm thickness at 12?keV. The speckle suppressor was tested on the ID06 ESRF beamline with X-rays in the energy range from 9 to 15?keV. It was applied for the transformation of the phase–amplitude contrast to the pure amplitude contrast in full-field microscopy. PMID:25931099

  9. X-ray Studies of Galaxies

    NASA Technical Reports Server (NTRS)

    Brown, Beth A.

    2006-01-01

    I will give a brief history of X-ray astronomy, and discuss the current X-ray observatories and their discoveries. I will then focus on the discovery of X-rays from galaxies and galaxy clusters and why astronomers look at galaxies in X-rays (multiwavelength studies). Finally, I will discuss diffuse emission and X-ray source populations in normal (non-AGN) galaxies.

  10. Soft X-ray interferometry and holography

    Microsoft Academic Search

    S. Aoki; S. Kikuta

    1986-01-01

    Four types of soft X-ray interferometers are proposed, and two of them, Lloyd's mirror and Young's experiment are examined. Phase shifts of refracting objects are observed with these interferometers. Two types of X-ray holograms are taken. Gabor in-line X-ray holograms are recorded by using undulator radiation on X-ray resists. Two-dimensional lensless Fourier-transform X-ray holograms are recorded and reconstructed with visible

  11. X-ray sensitive video camera

    Microsoft Academic Search

    Randy Luhta; John A. Rowlands

    1993-01-01

    By converting the absorbed X-ray image directly to an electrical video signal, the x-ray sensitive video camera offers improved resolution and reduced veiling glare over a conventional x-ray image intensifier for medical fluoroscopy. Unfortunately, currently available x-ray sensitive video cameras are limited to a 1' field of view and poor quantum efficiency. We are developing an x-ray sensitive vidicon for

  12. Material separation in x-ray CT with energy resolved photon-counting detectors

    SciTech Connect

    Wang Xiaolan; Meier, Dirk; Taguchi, Katsuyuki; Wagenaar, Douglas J.; Patt, Bradley E.; Frey, Eric C. [Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland 21287 (United States); Gamma Medica-Ideas (AS), N-1364 Oslo (Norway); Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland 21287 (United States); Gamma Medica-Ideas, Northridge, California 91324 (United States); Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland 21287 (United States)

    2011-03-15

    Purpose: The objective of the study was to demonstrate that, in x-ray computed tomography (CT), more than two types of materials can be effectively separated with the use of an energy resolved photon-counting detector and classification methodology. Specifically, this applies to the case when contrast agents that contain K-absorption edges in the energy range of interest are present in the object. This separation is enabled via the use of recently developed energy resolved photon-counting detectors with multiple thresholds, which allow simultaneous measurements of the x-ray attenuation at multiple energies. Methods: To demonstrate this capability, we performed simulations and physical experiments using a six-threshold energy resolved photon-counting detector. We imaged mouse-sized cylindrical phantoms filled with several soft-tissue-like and bone-like materials and with iodine-based and gadolinium-based contrast agents. The linear attenuation coefficients were reconstructed for each material in each energy window and were visualized as scatter plots between pairs of energy windows. For comparison, a dual-kVp CT was also simulated using the same phantom materials. In this case, the linear attenuation coefficients at the lower kVp were plotted against those at the higher kVp. Results: In both the simulations and the physical experiments, the contrast agents were easily separable from other soft-tissue-like and bone-like materials, thanks to the availability of the attenuation coefficient measurements at more than two energies provided by the energy resolved photon-counting detector. In the simulations, the amount of separation was observed to be proportional to the concentration of the contrast agents; however, this was not observed in the physical experiments due to limitations of the real detector system. We used the angle between pairs of attenuation coefficient vectors in either the 5-D space (for non-contrast-agent materials using energy resolved photon-counting acquisition) or a 2-D space (for contrast agents using energy resolved photon-counting acquisition and all materials using dual-kVp acquisition) as a measure of the degree of separation. Compared to dual-kVp techniques, an energy resolved detector provided a larger separation and the ability to separate different target materials using measurements acquired in different energy window pairs with a single x-ray exposure. Conclusions: We concluded that x-ray CT with an energy resolved photon-counting detector with more than two energy windows allows the separation of more than two types of materials, e.g., soft-tissue-like, bone-like, and one or more materials with K-edges in the energy range of interest. Separating material types using energy resolved photon-counting detectors has a number of advantages over dual-kVp CT in terms of the degree of separation and the number of materials that can be separated simultaneously.

  13. Prospects for in vivo estimation of photon linear attenuation coefficients using postprocessing dual-energy CT imaging on a commercial scanner: Comparison of analytic and polyenergetic statistical reconstruction algorithms

    PubMed Central

    Evans, Joshua D.; Whiting, Bruce R.; O’Sullivan, Joseph A.; Politte, David G.; Klahr, Paul H.; Yu, Yaduo; Williamson, Jeffrey F.

    2013-01-01

    Purpose: Accurate patient-specific photon cross-section information is needed to support more accurate model-based dose calculation for low energy photon-emitting modalities in medicine such as brachytherapy and kilovoltage x-ray imaging procedures. A postprocessing dual-energy CT (pDECT) technique for noninvasive in vivo estimation of photon linear attenuation coefficients has been experimentally implemented on a commercial CT scanner and its accuracy assessed in idealized phantom geometries. Methods: Eight test materials of known composition and density were used to compare pDECT-estimated linear attenuation coefficients to NIST reference values over an energy range from 10 keV to 1 MeV. As statistical image reconstruction (SIR) has been shown to reconstruct images with less random and systematic error than conventional filtered backprojection (FBP), the pDECT technique was implemented with both an in-house polyenergetic SIR algorithm, alternating minimization (AM), as well as a conventional FBP reconstruction algorithm. Improvement from increased spectral separation was also investigated by filtering the high-energy beam with an additional 0.5 mm of tin. The law of propagated uncertainty was employed to assess the sensitivity of the pDECT process to errors in reconstructed images. Results: Mean pDECT-estimated linear attenuation coefficients for the eight test materials agreed within 1% of NIST reference values for energies from 1 MeV down to 30 keV, with mean errors rising to between 3% and 6% at 10 keV, indicating that the method is unbiased when measurement and calibration phantom geometries are matched. Reconstruction with FBP and AM algorithms conferred similar mean pDECT accuracy. However, single-voxel pDECT estimates reconstructed on a 1 × 1 × 3 mm3 grid are shown to be highly sensitive to reconstructed image uncertainty; in some cases pDECT attenuation coefficient estimates exhibited standard deviations on the order of 20% around the mean. Reconstruction with the statistical AM algorithm led to standard deviations roughly 40% to 60% less than FBP reconstruction. Additional tin filtration of the high energy beam exhibits similar pDECT estimation accuracy as the unfiltered beam, even when scanning with only 25% of the dose. Using the law of propagated uncertainty, low Z materials are found to be more sensitive to image reconstruction errors than high Z materials. Furthermore, it is estimated that reconstructed CT image uncertainty must be limited to less than 0.25% to achieve a target linear-attenuation coefficient estimation uncertainty of 3% at 28 keV. Conclusions: That pDECT supports mean linear attenuation coefficient measurement accuracies of 1% of reference values for energies greater than 30 keV is encouraging. However, the sensitivity of the pDECT measurements to noise and systematic errors in reconstructed CT images warrants further investigation in more complex phantom geometries. The investigated statistical reconstruction algorithm, AM, reduced random measurement uncertainty relative to FBP owing to improved noise performance. These early results also support efforts to increase DE spectral separation, which can further reduce the pDECT sensitivity to measurement uncertainty. PMID:24320525

  14. Optimized Volumetric Scanning for X-Ray Array Sources

    SciTech Connect

    Lehman, S K; Foudray, A M; Wang, A; Kallman, J S; Martz, H

    2009-09-29

    Non-destructive evaluation (NDE) is the science and technology of determining non-invasively the internal structure of manufactured parts, objects, and materials. NDE application areas include medicine, industrial manufacturing, military, homeland security, and airport luggage screening. X-ray measurement systems are most widely used because of their ability to image through a wide range of material densities (from human tissue in medical applications to the dense materials of weapon components). Traditional x-ray systems involve a single source and detector system that rotate and/or translate about the object under evaluation. At each angular location, the source projects x-rays through the object. The rays undergo attenuation proportional to the density of the object's constitutive material. The detector records a measure of the attenuation. Mathematical algorithms are used to invert the forward attenuated ray projection process to form images of the object. This is known as computed tomography (CT). In recent years, the single-source x-ray NDE systems have been generalized to arrays of x-ray sources. Array sources permit multiple views of the object with fewer rotations and translations of the source/detector system. The spatially diverse nature of x-ray array sources has the potential of reducing data collection time, reducing imaging artifacts, and increasing the resolution of the resultant images. Most of the existing CT algorithms were not derived from array source models with a spatially diverse set of viewing perspectives. Single-source x-ray CT data collection, processing, and imaging methods and algorithms are not applicable when the source location is expanded from one dimension (a rotating and/or translating point source) to two (a rotating and/or translating array). They must be reformulated. The goal of this project is to determine the applicability of x-ray array sources to problems of interest to LLNL and its customers. It is believed array source data collection will be faster while yielding higher resolution reconstructions with fewer artifacts. There are three tasks in the research: (1) Develop forward array source analytic and computational models; (2) Research and develop array source reconstruction algorithms; and (3) Perform experiments.

  15. Measurement of polycapillary parameters in the long-wave x-ray spectrum

    Microsoft Academic Search

    Dmitrii I. Gruev; Svetlana V. Nikitina; Vladimir P. Petukhov; Aleksei A. Priladyshev

    2002-01-01

    The results of measurements of x-ray polycapillary transmission coefficient for 1.5 keV photons are given. As a source of quasi-monochromatic x-ray, a transmission-type aluminum anode x-ray tube was used for investigation of capillaries' optic features. The dependence of radiation intensity at the exit from the poly-capillary tube on the diameter of the radiation source, capillary length, and focal distance was

  16. Ultrafast X-ray Absorption Spectroscopy using Laser-Driven Electron X-ray Sources (LEXS)

    E-print Network

    Guo, Ting

    Ultrafast X-ray Absorption Spectroscopy using Laser-Driven Electron X-ray Sources (LEXS) Guangjun: ultrafast x-rays, x-ray absorption spectroscopy, terawatt lasers, ultrafast reaction dynamics, atomic motion Shields Avenue, Davis, CA 95616 ABSTRACT A laser driven electron x-ray source (LEXS) using a high

  17. Portable X-Ray Device

    NASA Technical Reports Server (NTRS)

    1983-01-01

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

  18. Multi-frequency characterization of the speed of sound and attenuation coefficient for longitudinal transmission of freshly excised human skulls.

    PubMed

    Pichardo, Samuel; Sin, Vivian W; Hynynen, Kullervo

    2011-01-01

    For medical applications of ultrasound inside the brain, it is necessary to understand the relationship between the apparent density of skull bone and its corresponding speed of sound and attenuation coefficient. Although there have been previous studies exploring this phenomenon, there is still a need to extend the measurements to cover more of the clinically relevant frequency range. The results of measurements of the longitudinal speed of sound and attenuation coefficient are presented for specimens of human calvaria. The study was performed for the frequencies of 0.27, 0.836, 1.402, 1.965 and 2.525 MHz. Specimens were obtained from fresh cadavers through a protocol with the Division of Anatomy of the University of Toronto. The protocol was approved by the Research Ethics Board of Sunnybrook Health Sciences Centre. The specimens were mounted in polycarbonate supports that were marked for stereoscopic positioning. Computer tomography (CT) scans of the skulls mounted on their supports were performed, and a three-dimensional skull surface was reconstructed. This surface was used to guide a positioning system to ensure the normal sound incidence of an acoustic signal. This signal was produced by a focused device with a diameter of 5 cm and a focal length of 10 cm. Measurements of delay in time of flight were carried out using a needle hydrophone. Measurements of effective transmitted energy were carried out using a radiation force method with a 10 µg resolution scale. Preliminary functions of speed of sound and attenuation coefficient, both of which are related to apparent density, were established using a multi-layer propagation model that takes into account speed of sound, density and thickness of the layer. An optimization process was executed from a large set of random functions and the best functions were chosen for those ones that closest reproduced the experimental observations. The final functions were obtained after a second pass of the optimization process was executed, but this time using a finite-difference time-difference solution of the Westervelt equation, which is more precise than the multi-layer model but much more time consuming for computation. For six of seven specimens, measurements were carried out on five locations on the calvaria, and for the other specimen three measurements were made. In total, measurements were carried out on 33 locations. Results indicated the presence of dispersion effects and that these effects are different according to the type of bone in the skull (cortical and trabecular). Additionally, both the speed of sound and attenuation showed dependence on the skull density that varied with the frequency. Using the optimal functions and the information of density from the CT scans, the average values (±s.d.) of the speed of sound for cortical bone were estimated to be 2384(± 130), 2471(± 90), 2504(± 120), 2327(± 90) and 2053(± 40) m s(-1) for the frequencies of 270, 836, 1402, 1965 and 2526 kHz, respectively. For trabecular bone, and in the same order of frequency values, the speeds of sound were 2140(± 130), 2300(± 100), 2219(± 200), 2133(± 130) and 1937(± 40) m s(-1), respectively. The average values of the attenuation coefficient for cortical bone were 33(± 9), 240(± 9) and 307(± 30) Np m(-1) for the frequencies of 270, 836, and 1402, respectively. For trabecular bone, and in the same order of frequency values, the average values of the attenuation coefficient were 34(± 13), 216(± 16) and 375(± 30) Np m(-1), respectively. For frequencies of 1.965 and 2.525 MHz, no measurable radiation force was detected with the setup used. PMID:21149950

  19. Multi-frequency characterization of the speed of sound and attenuation coefficient for longitudinal transmission of freshly excised human skulls

    PubMed Central

    Pichardo, Samuel; Sin, Vivian W; Hynynen, Kullervo

    2011-01-01

    For medical applications of ultrasound inside the brain, it is necessary to understand the relationship between the apparent density of skull bone and its corresponding speed of sound and attenuation coefficient. Although there have been previous studies exploring this phenomenon, there is still a need to extend the measurements to cover more of the clinically relevant frequency range. The results of measurements of the longitudinal speed of sound and attenuation coefficient are presented for specimens of human calvaria. The study was performed for the frequencies of 0.27, 0.836, 1.402, 1.965 and 2.525 MHz. Specimens were obtained from fresh cadavers through a protocol with the Division of Anatomy of the University of Toronto. The protocol was approved by the Research Ethics Board of Sunnybrook Health Sciences Centre. The specimens were mounted in polycarbonate supports that were marked for stereoscopic positioning. Computer tomography (CT) scans of the skulls mounted on their supports were performed, and a three-dimensional skull surface was reconstructed. This surface was used to guide a positioning system to ensure the normal sound incidence of an acoustic signal. This signal was produced by a focused device with a diameter of 5 cm and a focal length of 10 cm. Measurements of delay in time of flight were carried out using a needle hydrophone. Measurements of effective transmitted energy were carried out using a radiation force method with a 10 ?g resolution scale. Preliminary functions of speed of sound and attenuation coefficient, both of which are related to apparent density, were established using a multi-layer propagation model that takes into account speed of sound, density and thickness of the layer. An optimization process was executed from a large set of random functions and the best functions were chosen for those ones that closest reproduced the experimental observations. The final functions were obtained after a second pass of the optimization process was executed, but this time using a finite-difference time-difference solution of the Westervelt equation, which is more precise than the multi-layer model but much more time consuming for computation. For six of seven specimens, measurements were carried out on five locations on the calvaria, and for the other specimen three measurements were made. In total, measurements were carried out on 33 locations. Results indicated the presence of dispersion effects and that these effects are different according to the type of bone in the skull (cortical and trabecular). Additionally, both the speed of sound and attenuation showed dependence on the skull density that varied with the frequency. Using the optimal functions and the information of density from the CT scans, the average values (±s.d.) of the speed of sound for cortical bone were estimated to be 2384(±130), 2471(±90), 2504(±120), 2327(±90) and 2053(±40) m s?1 for the frequencies of 270, 836, 1402, 1965 and 2526 kHz, respectively. For trabecular bone, and in the same order of frequency values, the speeds of sound were 2140(±130), 2300(±100), 2219(±200), 2133(±130) and 1937(±40) m s?1, respectively. The average values of the attenuation coefficient for cortical bone were 33(±9), 240(±9) and 307(±30) Np m?1 for the frequencies of 270, 836, and 1402, respectively. For trabecular bone, and in the same order of frequency values, the average values of the attenuation coefficient were 34(±13), 216(±16) and 375(±30) Np m?1, respectively. For frequencies of 1.965 and 2.525 MHz, no measurable radiation force was detected with the setup used. PMID:21149950

  20. L -subshell vacancy decay processes for elements with 52?Z?57 following ionization using Mn K? x rays

    NASA Astrophysics Data System (ADS)

    Sharma, Veena; Kumar, Sanjeev; Mehta, D.; Singh, Nirmal

    2008-07-01

    The Li - (i=1-3) subshell x-ray spectra for the T52e , I53 , C55s , B56a , and L57a elements excited by Mn K? ( EK?2=5.888keV and EK?1=5.899keV ) x rays have been investigated using the F55e radioisotope in conjunction with a Cr absorber. A low-energy Ge detector was used to measure the L x rays at an emission angle ?=126° , where the second-order Legendre polynomial term P2 (cos?) associated with the angular distribution is annulled. In the case of the B56a and L57a elements, alignment of the L3 -subshell vacancy states was investigated through angular distribution measurements of the emitted L3 -subshell x rays. The L?1,2 and L?2,15 x-ray groups are observed to be nearly isotropic, while the data for the pure Ll (L3-M1) x-ray emission are indicative of a small anisotropic trend, though within experimental error. The integral x-ray fluorescence cross sections are deduced and interpreted in terms of Li -subshell photoionization cross sections, fluorescence and Coster-Kronig yields, and x-ray emission rates. The L2 -subshell x-ray cross sections for L57a measured using targets of lanthanum (III) fluoride and dilanthanum (III) trioxide are found to be unusually higher. The enhancement is observed due to the contribution of the L2 -subshell radiative resonant Raman scattering (RRS) of Mn K? x rays having energy around the L2 -subshell binding energy of L57a in these compounds. Also, the observed enhancement of the L3 -subshell x-ray cross sections in L57a is suggestive of intrashell vacancy transfer via L2-L3 Coster-Kronig RRS transitions. The L2 -subshell total RRS cross sections in L57a have been deduced from the present measured attenuation coefficients for Mn K? x rays in La2O3 and LaF3 . The L2 -subshell radiative and total RRS cross sections in L57a using LaF3 are higher by ˜30% than those using La2O3 . The contribution of processes predicted in the framework of Mozouchi’s four-band model involving inner subshells along with the valence and conduction bands of these wide-band-gap insulator compounds is likely to account for the observed results. The L2 -subshell radiative and L2-L3 Coster-Kronig yields and the ratio of the L2-M4 and L2-N4 radiative RRS intensities in both La compounds are found to be same and are consistent with values from photoexcited vacancy decay. The L2 -subshell radiative RRS was also observed to be isotropic.

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

    SciTech Connect

    Sisniega, A.; Vaquero, J. J., E-mail: juanjose.vaquero@uc3m.es [Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Madrid ES28911 (Spain); Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007 (Spain); Desco, M. [Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Madrid ES28911 (Spain) [Departamento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Madrid ES28911 (Spain); Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007 (Spain); Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Madrid ES28029 (Spain)

    2014-01-15

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

  2. Estimation of the Inherent Optical Properties of Natural Waters from the Irradiance Attenuation Coefficient and Reflectance in the Presence of Raman Scattering

    Microsoft Academic Search

    Hubert Loisel; Dariusz Stramski

    2000-01-01

    By means of radiative transfer simulations we developed a model for estimating the absorption a , the scattering b , and the backscattering b b coefficients in the upper ocean from irradiance reflectance just beneath the sea surface, R ( 0 ), and the average attenuation coefficient for downwelling irradiance, K d 1 , between the surface and the first

  3. Alpha proton x ray spectrometer

    NASA Technical Reports Server (NTRS)

    Rieder, Rudi; Waeke, H.; Economou, T.

    1994-01-01

    Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

  4. Hard X ray imaging telescope

    Microsoft Academic Search

    P. Lubin

    1990-01-01

    This final report covers the work carried out under the LLNL Contract Number B063682, Subcontractor Regents University of California at Santa Barbara. The research carried out under this contract involves the construction of a telemetry, target acquisition and guidance system, and of a light-weight gondola to house an x ray spectrometer. This work is part of the design and construction

  5. Synchrotron X-ray Measurements

    E-print Network

    Synchrotron X-ray Measurements NANOMATERIALS Our objective is to provide comprehensive descriptions of the semiconductor industry's "Grand Challenges" is to develop an alternative to the SiO2 gate dielectric. Integrated circuits exhibiting greater speed and lower power consumption are no longer attainable with ultrathin ( 2

  6. X-Ray Diffractive Optics

    NASA Technical Reports Server (NTRS)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

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

  7. X-ray backscatter imaging

    NASA Astrophysics Data System (ADS)

    Dinca, Dan-Cristian; Schubert, Jeffrey R.; Callerame, J.

    2008-04-01

    In contrast to transmission X-ray imaging systems where inspected objects must pass between source and detector, Compton backscatter imaging allows both the illuminating source as well as the X-ray detector to be on the same side of the target object, enabling the inspection to occur rapidly and in a wide variety of space-constrained situations. A Compton backscatter image is similar to a photograph of the contents of a closed container, taken through the container walls, and highlights low atomic number materials such as explosives, drugs, and alcohol, which appear as especially bright objects by virtue of their scattering characteristics. Techniques for producing X-ray images based on Compton scattering will be discussed, along with examples of how these systems are used for both novel security applications and for the detection of contraband materials at ports and borders. Differences between transmission and backscatter images will also be highlighted. In addition, tradeoffs between Compton backscatter image quality and scan speed, effective penetration, and X-ray source specifications will be discussed.

  8. Lights, X-rays, oxygen!

    PubMed

    Jez, Joseph M; Blankenship, Robert E

    2014-08-14

    Photosystem II uses metal ions to oxidize water to form O2. Two recent papers employ the new technique of serial femtosecond crystallography utilizing X-ray free-electron lasers and nanocrystals to obtain initial structures of intermediate states of photosystem II catalysis at the site of oxygen production. PMID:25126779

  9. Measurements of the thermal coefficient of optical attenuation at different depth regions of in vivo human skins using optical coherence tomography: a pilot study.

    PubMed

    Su, Ya; Yao, X Steve; Li, Zhihong; Meng, Zhuo; Liu, Tiegen; Wang, Longzhi

    2015-02-01

    We present detailed measurement results of optical attenuation's thermal coefficients (referenced to the temperature of the skin surface) in different depth regions of in vivo human forearm skins using optical coherence tomography (OCT). We first design a temperature control module with an integrated optical probe to precisely control the surface temperature of a section of human skin. We propose a method of using the correlation map to identify regions in the skin having strong correlations with the surface temperature of the skin and find that the attenuation coefficient in these regions closely follows the variation of the surface temperature without any hysteresis. We observe a negative thermal coefficient of attenuation in the epidermis. While in dermis, the slope signs of the thermal coefficient of attenuation are different at different depth regions for a particular subject, however, the depth regions with a positive (or negative) slope are different in different subjects. We further find that the magnitude of the thermal coefficient of attenuation coefficient is greater in epidermis than in dermis. We believe the knowledge of such thermal properties of skins is important for several noninvasive diagnostic applications, such as OCT glucose monitoring, and the method demonstrated in this paper is effective in studying the optical and biological properties in different regions of skin. PMID:25780740

  10. Identification of steel by X-ray fluorescence analysis with a pyroelectric X-ray generator

    Microsoft Academic Search

    Hiroyuki Ida; Jun Kawai

    2004-01-01

    An application of X-ray fluorescence analysis with a pyroelectric X-ray generator is presented. Steel standard samples were identified by X-ray fluorescence analysis with this novel X-ray generator to check its capability for performing qualitative and quantitative analysis as an X-ray source for X-ray fluorescence spectrometers. Cr, Ni, V, Co, and W were detected in steel standard samples. V and Cr

  11. The Discovery of Soft X-Ray-loud Broad Absorption Line Quasars

    NASA Astrophysics Data System (ADS)

    Ghosh, Kajal K.; Punsly, Brian

    2008-02-01

    It has been known for more than a decade that BALQSOs (broad absorption line quasars) are highly attenuated in the X-ray regime compared to other quasars, especially in the soft band (<1 keV). Using X-ray selection techniques, we have found ``soft X-ray-loud'' BALQSOs that, by definition, have soft X-ray (0.3 keV) to UV (3000 Å) flux density ratios that are higher than typical non-BAL radio-quiet quasars. Our sample of three sources includes one LoBALQSO (low-ionization BALQSO), which is generally considered to be the most highly attenuated in X-rays. The three QSOs are the only known BALQSOs that have X-ray observations that are consistent with no intrinsic soft X-ray absorption. The existence of a large X-ray luminosity and the hard ionizing continuum that it presents to potential UV absorption gas is in conflict with the ionization states that are conducive to line-driving forces within BAL winds (especially for the LoBALs).

  12. Center for X-Ray Optics, 1986

    SciTech Connect

    Not Available

    1987-07-01

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

  13. Imaging techniques in X-ray astronomy.

    NASA Technical Reports Server (NTRS)

    Gursky, H.

    1973-01-01

    Some of the imaging problems encountered in space-borne X-ray astronomy are reviewed, along with the techniques considered for their solution. Following a discussion of X-ray focussing and X-ray image processing, the development of X-ray imaging devices is surveyed. It is shown that the imaging devices that will be used in X-ray astronomy will take advantage of developments intended for infrared and optical astronomy. The special requirements of X-ray observation - especially, single photon detection and high time resolution - rule out the use of existing devices, particularly because of readout problems.

  14. Filtration of micron-sized particles in granular media revealed by x-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Al-Abduwani, F. A. H.; Farajzadeh, R.; van den Broek, W. M. G. T.; Currie, P. K.; Zitha, P. L. J.

    2005-10-01

    We investigate the deep-bed filtration of micron-sized hematite particles suspended in distilled water during flow in siliceous granular porous media, where particle retention is mostly due to surface (van der Waals and electrostatic) interactions. We show that x-ray computed tomography enables three-dimensional images of the filtration process to be generated. The one-dimensional filtrate concentration profiles obtained by averaging the images over sections perpendicular to the flow direction are rapidly decaying functions of the distance from the porous medium inlet and slide upward in the course of time, consistently with the filtration model presented by Herzig et al. [Ind. Eng. Chem. 62, 8 (1970)]. Finally, the filtration coefficient is found to decrease rapidly as a function of time: This indicates that the attractive interaction responsible for the retention of the hematite particles is strongly attenuated as the particles accumulate of the pore surfaces.

  15. Theoretical study of the X-ray emission from astrophysical shock waves

    NASA Technical Reports Server (NTRS)

    Raymond, J.

    1986-01-01

    Theoretical X-ray emission spectra are needed to interpret the X-ray emission observed by many low and moderate resolution X-ray instruments, and to provide diagnosis of physical conditions for high resolution spectra. Over the past decade, a set of model codes which compute the X-ray and XUV emission for a wide set of physical conditions, including high or low densities, photoionized gas, and time-dependent ionization balance was developed. In the past year, the atomic rate coefficients in the code was improved. Further capabilities were added, and applied to several astrophysical problems.

  16. Inversion of the broken ray transform in the case of energy-dependent attenuation.

    PubMed

    Krylov, R; Katsevich, A

    2015-06-01

    Broken Ray transform (BRT) arises when one considers a narrow x-ray beam propagating through medium under the assumption of single scattering. Previous algorithms for inverting the BRT assumed that the medium is characterized by a single attenuation coefficient ?. However x-rays lose their energy after Compton scattering and the energy loss depends on the scattering angle. Since the attenuation coefficient depends on energy, the ?'s before and after scattering are different. When there are three or more detectors one should distinguish not only between ?'s that are 'seen' by x-rays before and after scattering, but also between ?'s that are 'seen' by x-rays traveling towards different detectors.The main thrust of this paper is inversion of the BRT with N ? 3 detectors under the assumption that the attenuation coefficient can be accurately approximated by a linear function of energy within the window of relevant energies. When the number of detectors is four or greater, we derive a family of inversion formulas. If N > 4, we find the optimal formula, which provides the best stability with respect to noise in the data. If N = 4, the family collapses into a single formula and no optimization is possible. If ? is independent of energy, N = 3 is sufficient for inversion. We also develop iterative reconstruction algorithms that can use global and local data. The results of testing the algorithms are presented. PMID:25974246

  17. Inversion of the broken ray transform in the case of energy-dependent attenuation

    NASA Astrophysics Data System (ADS)

    Krylov, R.; Katsevich, A.

    2015-06-01

    Broken Ray transform (BRT) arises when one considers a narrow x-ray beam propagating through medium under the assumption of single scattering. Previous algorithms for inverting the BRT assumed that the medium is characterized by a single attenuation coefficient ?. However x-rays lose their energy after Compton scattering and the energy loss depends on the scattering angle. Since the attenuation coefficient depends on energy, the ?’s before and after scattering are different. When there are three or more detectors one should distinguish not only between ?’s that are ‘seen’ by x-rays before and after scattering, but also between ?’s that are ‘seen’ by x-rays traveling towards different detectors. The main thrust of this paper is inversion of the BRT with N ? 3 detectors under the assumption that the attenuation coefficient can be accurately approximated by a linear function of energy within the window of relevant energies. When the number of detectors is four or greater, we derive a family of inversion formulas. If N > 4, we find the optimal formula, which provides the best stability with respect to noise in the data. If N = 4, the family collapses into a single formula and no optimization is possible. If ? is independent of energy, N = 3 is sufficient for inversion. We also develop iterative reconstruction algorithms that can use global and local data. The results of testing the algorithms are presented.

  18. Beam-hardening in simulated X-ray tomography

    Microsoft Academic Search

    K. Ramakrishna; K. Muralidhar; P. Munshi

    2006-01-01

    Polychromatic X-ray sources are used universally in computerized tomography to obtain adequate intensity of photons. These sources, however, can produce some artifacts in the reconstructed image due to non-linearity. Beam-hardening is one such artifact, which produces false line integrals due the photon-energy dependence of the attenuation co-efficient.The present investigation deals with the process of estimating the equivalent monoenergetic data, m,

  19. Determination of power-law attenuation coefficient and dispersion spectra in multi-wall carbon nanotube

    E-print Network

    Gladden, Josh

    for a set of multi-wall carbon nanotube MWCNT -nylon composites from pure nylon to 20% MWCNT by weight coefficients of the respective samples are found to decrease with increasing MWCNT content and a similar trend with increasing MWCNT content indicating an increase in the mechanical moduli. © 2009 Acoustical Society

  20. Practical energy response estimation of photon counting detectors for spectral X-ray imaging

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Goo; Lee, Jongha; Sung, Younghun; Lee, SeongDeok

    2010-04-01

    Spectral X-ray imaging is a promising technique to drastically improve the diagnostic quality of radiography and computed tomography (CT), since it enables material decomposition and/or identification based on the energy dependency of material-specific X-ray attenuation. Unlike the charge-integration based X-ray detectors, photon counting X-ray detectors (PCXDs) can discriminate the energies of incident X-ray photons and thereby multi-energy images can be obtained in single exposure. However, the measured data are not accurate since the spectra of incident X-rays are distorted according to the energy response function (ERF) of a PCXD. Thus ERF should be properly estimated in advance for accurate spectral imaging. This paper presents a simple method for ERF estimation based on a polychromatic X-ray source that is widely used for medical imaging. The method consists of three steps: source spectra measurement, detector spectra reconstruction, and ERF inverse estimation. Real spectra of an X-ray tube are first measured at all kVs by using an X-ray spectrometer. The corresponding detector spectra are obtained by threshold scans. The ERF is then estimated by solving the inverse problem. Simulations are conducted to demonstrate the concept of the proposed method.

  1. a Laboratory-Based X-Ray Phase Contrast Imaging Scanner with Applications in Biomedical and Non-Medical Disciplines

    NASA Astrophysics Data System (ADS)

    Hagen, C. K.; Diemoz, P. C.; Endrizzi, M.; Munro, P. R. T.; Szafraniec, M. B.; Millard, T. P.; Speller, R.; Olivo, D. A.

    2014-02-01

    X-ray phase contrast imaging (XPCi) provides a much higher visibility of low-absorbing details than conventional, attenuation-based radiography. This is due to the fact that image contrast is determined by the unit decrement of the real part of the complex refractive index of an object rather than by its imaginary part (the absorption coefficient), which can be up to 1000 times larger for energies in the X-ray regime. This finds applications in many areas, including medicine, biology, material testing, and homeland security. Until lately, XPCi has been restricted to synchrotron facilities due to its demanding coherence requirements on the radiation source. However, edge illumination XPCi, first developed by one of the authors at the ELETTRA Synchrotron in Italy, substantially relaxes these requirements and therefore provides options to overcome this problem. Our group has built a prototype scanner that adapts the edge-illumination concept to standard laboratory conditions and extends it to large fields of view. This is based on X-ray sources and detectors available off the shelf, and its use has led to impressive results in mammography, cartilage imaging, testing of composite materials and security inspection. This article presents the method and the scanner prototype, and reviews its applications in selected biomedical and non-medical disciplines.

  2. MATHEMATICAL TECHNIQUES FOR X-RAY ANALYZERS

    EPA Science Inventory

    Mathematical techniques and subsequent computer software were developed to process energy-dispersive x-ray fluorescence spectra for elemental analysis of airborne particulate matter collected on filters. The research concerned two areas: (1) determination of characteristic x-ray ...

  3. Spectral analysis of X-ray binaries

    E-print Network

    Fridriksson, Joel Karl

    2011-01-01

    In this thesis, I present work from three separate research projects associated with observations of X-ray binaries. Two of those revolve around spectral characteristics of neutron star low-mass X-ray binaries (NS-LMXBs), ...

  4. Aspergillosis - chest x-ray (image)

    MedlinePLUS

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

  5. Producing X-rays at the APS

    SciTech Connect

    None

    2011-01-01

    An introduction and overview of the Advanced Photon Source at Argonne National Laboratory, the technology that produces the brightest X-ray beams in the Western Hemisphere, and the research carried out by scientists using those X-rays.

  6. Producing X-rays at the APS

    ScienceCinema

    None

    2013-04-19

    An introduction and overview of the Advanced Photon Source at Argonne National Laboratory, the technology that produces the brightest X-ray beams in the Western Hemisphere, and the research carried out by scientists using those X-rays.

  7. Soft X-ray Polarimetry

    NASA Astrophysics Data System (ADS)

    Marshall, Herman; Schulz, Norbert S.; Heilmann, Ron; Kochanski, Kelly

    2012-09-01

    We developed an instrument design capable of measuring linear X-ray polarization over a broad-band using conventional spectroscopic optics. A set of multilayer-coated flats reflects the dispersed X-rays to the instrument detectors. The intensity variation with position angle is measured to determine three Stokes parameters: I, Q, and U -- all as a function of energy. By laterally grading the multilayer optics and matching the dispersion of the gratings, one may take advantage of high multilayer reflectivities and achieve modulation factors >50% over the entire 0.2 to 0.8 keV band. This instrument could be used in a small orbiting mission or the approach could be used on a large dispersive spectrometric facility. We present progress on laboratory work to demonstrate the capabilities of key components.

  8. Microgap x-ray detector

    SciTech Connect

    Wuest, Craig R. (Danville, CA); Bionta, Richard M. (Livermore, CA); Ables, Elden (Livermore, CA)

    1994-01-01

    An x-ray detector which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope.

  9. Microgap x-ray detector

    DOEpatents

    Wuest, C.R.; Bionta, R.M.; Ables, E.

    1994-05-03

    An x-ray detector is disclosed which provides for the conversion of x-ray photons into photoelectrons and subsequent amplification of these photoelectrons through the generation of electron avalanches in a thin gas-filled region subject to a high electric potential. The detector comprises a cathode (photocathode) and an anode separated by the thin, gas-filled region. The cathode may comprise a substrate, such a beryllium, coated with a layer of high atomic number material, such as gold, while the anode can be a single conducting plane of material, such as gold, or a plane of resistive material, such as chromium/silicon monoxide, or multiple areas of conductive or resistive material, mounted on a substrate composed of glass, plastic or ceramic. The charge collected from each electron avalanche by the anode is passed through processing electronics to a point of use, such as an oscilloscope. 3 figures.

  10. The Electromagnetic Spectrum: X-Rays

    NSDL National Science Digital Library

    This site provided by National Aeronautics and Space Administration contains an introduction to X-rays and their uses in medicine and astronomy. Descriptions of the first X-ray observations, how they are used to visualize parts of the body, and results from X-ray astronomy are provided. The site contains striking astronomical images made with X-rays. Also provided are links to similar sites on the other electromagnetic spectrum regions.

  11. X-rays from old star clusters

    E-print Network

    Frank Verbunt

    1999-07-15

    A brief overview is given of X-ray observations of old clusters. Most X-ray sources in old open clusters are interacting binaries, formed via evolution of a primordial binary, and emitting X-rays because of magnetic activity; however, a sizable fraction of the cluster sources is not well understood, including some of the most luminous ones. Globular clusters appear to contain fewer magnetically active X-ray sources than expected if one scales from old open clusters by mass.

  12. Advanced x-ray imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Callas, John L. (Inventor); Soli, George A. (Inventor)

    1998-01-01

    An x-ray spectrometer that also provides images of an x-ray source. Coded aperture imaging techniques are used to provide high resolution images. Imaging position-sensitive x-ray sensors with good energy resolution are utilized to provide excellent spectroscopic performance. The system produces high resolution spectral images of the x-ray source which can be viewed in any one of a number of specific energy bands.

  13. Coherent lensless X-ray imaging

    Microsoft Academic Search

    Henry N. Chapman; Keith A. Nugent

    2010-01-01

    Very high resolution X-ray imaging has been the subject of considerable research over the past few decades. However, the spatial resolution of these methods is limited by the manufacturing quality of the X-ray optics. More recently, lensless X-ray imaging has emerged as a powerful approach that is able to circumvent this limitation. A number of classes of lensless X-ray imaging

  14. Establishment of ANSI N13.11 X-ray radiation fields for personal dosimetry performance test by computation and experiment.

    PubMed Central

    Kim, J L; Kim, B H; Chang, S Y; Lee, J K

    1997-01-01

    This paper describes establishment by computational and experimental methods of the American National Standard Institute (ANSI) N13.11 X-ray radiation fields by the Korea Atomic Energy Research Institute (KAERI). These fields were used in the standard irradiations of various personal dosimeters for the personal dosimetry performance test program performed by the Ministry of Science and Technology of Korea in the autumn of 1995. Theoretical X-ray spectra produced from two KAERI X-ray generators were estimated using a modified Kramers' theory with target attenuation and backscatter correction and their spectral distributions experimentally measured by a high-purity germanium semiconductor detector through proper corrections for measured pulse height distributions with photopeak efficiency, Compton fraction, and K-escape fraction. The average energies and conversion coefficients obtained from the computation and experimental methods, when compared with ANSI N13.11 and the recently published National Institute of Standards and Technology X-ray beams, appeared to be in good agreement--(+/-)3% between corresponding values--and thus, could be satisfactorily applied in the performance test of personal dosimeters. PMID:9467054

  15. X-ray Diagnostics of Broad Absorption Line Quasar Geometry

    E-print Network

    Brian Punsly; Sebastian Lipari

    2005-03-09

    A new generation of sensitive X-ray measurements are indicating that the existence of X-ray attenuation column densities, $N_{H}>10^{24}\\mathrm{cm}^{-2}$ is quite common amongst broad absorption line quasars (BALQSOs). This is significant to the geometry of the broad absorption line (BAL) outflow. In particular, such an X-ray shield also shields equatorial accretion disk winds from the UV, thereby preventing high velocity equatorial outflows from being launched. By contrast, bipolar winds initiated by continuum radiation pressure from the funnel of a slim accretion disk flare outward (like a trumpet) and offer vastly different absorbing columns to the X-ray and UV emission which are emitted from distinct regions of the disk, $\\sim 6M$ and $\\sim 10M-40M$, respectively (where $M$ is the radius of the black hole). Recent numerical work indicates that it is also possible to launch bipolar outflows from the inner regions of a thin disk. The recent discovery with VLBI that the Galactic analog of a BALQSO, the X-ray binary Circinus X-1 (with high velocity P Cygni X-ray absorption lines) is viewed virtually along the radio jet axis (and therefore along the spin axis of the black hole and the normal to the accretion disk) has rekindled interest in the bipolar models of BALQSOs. We explore this possibility by studying the nearest BAL QSO, MRK 231. High resolution 2-D optical spectroscopy and VLBI mappings of the radio jet axis indicates that the BAL outflow is parallel to the parsec scale radio jet.

  16. Application-Oriented X-ray Grating Interferometer

    NASA Astrophysics Data System (ADS)

    Revol, V.; Kottler, C.; Kaufmann, R.; Jerjen, I.; Lüthi, T.; Cardot, F.; Niedermann, Ph.; Sennhauser, U.; Straumann, U.; Urban, C.

    2010-04-01

    Grating-based Differential Phase Contrast X-ray imaging (DPCi) provides, in one measurement, unique information about the absorption coefficient, the index of refraction and the microscopic structure of a sample at hard X-ray frequencies11-17. For this reason, DPCi can potentially overcome the limitations of classical absorption-based radiography, notably for weakly absorbing materials. However, the implementation of the technology in industrial applications is still restricted due to the limited field of view and the insufficient contrast at high X-ray energies. Here, we report on a new experimental setup with field of view 5×7 cm2 that acquires single projections as well as Computerized Tomographic (CT) measurements of the sample. New micro-fabrication processes were developed to manufacture X-ray gratings with few defects. This allows the instrument to deliver images of industrial quality when operated with a conventional x-ray tube at 40 kV. The complementarity of DPCi with conventional absorption-based radiography was experimentally demonstrated.

  17. X-Ray Crystallography Reagent

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  18. X-ray Diode Preparation

    SciTech Connect

    Henderson, D J; Good, D E; Hogge, K W; Molina, I; Howe, R A; Lutz, S S; Flores, P A; McGillivray, K D; Skarda, W M; Nelson, D S; Ormond, E S

    2011-06-16

    A rod pinch x-ray diode assembly culminates in a coaxial anode cathode arrangement where a small anode rod extends through the aperture of a cathode plate. Shotto- shot repeatability in rod placement, and thus x-ray source spot position, has potential to positively affect radiographic image quality. Thus, how to both control and measure, according to a Cartesian coordinate system, anode rod tip displacement (x, y) (off the beam line-of-sight retical) and also anode rod tip extension (z) (along the line-of-sight center line) become salient issues relative to radiographic image set utility. To address these issues both hardware fabrication and x-ray diode assembly methods were reviewed, and additional controls were introduced. A photogrammetric procedure was developed to quantify anode rod tip position in situ. Computer models and mock-up assemblies with precision fiducials were produced to validate this procedure. Therefore, both anode rod tip displacement and anode rod tip extension parameters were successfully controlled. Rod position was measured and met the required specifications: (1) radial displacement <0.25 mm and (2) axial placement of ±0.25 mm. We demonstrated that precision control and measurement of large scale components is achievable in a pulse power system (i.e., hardware and operations). Correlations with diode performance and radiography are presented.

  19. Chest X-Ray (Chest Radiography)

    MedlinePLUS

    ... x-rays. top of page What does the equipment look like? View larger with caption The equipment typically used for chest x-rays consists of ... tube is positioned about six feet away. The equipment may also be arranged with the x-ray ...

  20. Center for X-ray Optics, 1988

    SciTech Connect

    Not Available

    1989-04-01

    This report briefly reviews the following topics: soft-x-ray imaging; reflective optics for hard x-rays; coherent XUV sources; spectroscopy with x-rays; detectors for coronary artery imaging; synchrotron-radiation optics; and support for the advanced light source.

  1. X-Rays, Pregnancy and You

    MedlinePLUS

    ... Radiation-Emitting Products and Procedures Medical Imaging Medical X-ray Imaging X-Rays, Pregnancy and You Pregnancy is a ... Publication No. (FDA) 94-8087 More in Medical X-ray Imaging Radiography Computed Tomography (CT) Dental Cone-beam Computed ...

  2. Twenty years of X-ray astronomy

    NASA Astrophysics Data System (ADS)

    Shklovskii, I. S.

    1982-09-01

    The history of X-ray astronomy is reviewed. Studies of solar X-ray emission and the discovery of galactic and metagalactic X-ray sources are considered, and results obtained with the Uhuru and HEAO-2 satellites are examined in detail.

  3. X-Ray Absorption Spectroscopy of Metallobiomolecules

    E-print Network

    Scott, Robert A.

    2/9/07 1 X-Ray Absorption Spectroscopy of Metallobiomolecules The Outskirts of Structural Biology 9, 07] This is a tutorial about the use of X-ray Absorption Spectroscopy (XAS) in biology, RG; Eisenberger, P; Kincaid, BM "X-ray Absorption Spectroscopy of Biological Molecules" Annu. Rev

  4. X-Ray Absorption Spectroscopy of Metallobiomolecules

    E-print Network

    Scott, Robert A.

    9/6/09 1 X-Ray Absorption Spectroscopy of Metallobiomolecules The Outskirts of Structural Biology 6, 09] This is a tutorial about the use of X-ray Absorption Spectroscopy (XAS) in biology, RG; Eisenberger, P; Kincaid, BM "X-ray Absorption Spectroscopy of Biological Molecules" Annu. Rev

  5. X-raying clumped stellar winds

    E-print Network

    L. M. Oskinova; W. -R. Hamann; A. Feldmeier

    2008-06-13

    X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from He-like ions in the X-ray spectra of O-stars highlighted problems with this general paradigm: the measured line ratios of highest ions are consistent with the location of the hottest X-ray emitting plasma very close to the base of the wind, perhaps indicating the presence of a corona, while measurements from lower ions conform with the wind-embedded shock model. Generally, to correctly model the emerging X-ray spectra, a detailed knowledge of the cool wind opacities based on stellar atmosphere models is prerequisite. A nearly grey stellar wind opacity for the X-rays is deduced from the analyses of high-resolution X-ray spectra. This indicates that the stellar winds are strongly clumped. Furthermore, the nearly symmetric shape of X-ray emission line profiles can be explained if the wind clumps are radially compressed. In massive binaries the orbital variations of X-ray emission allow to probe the opacity of the stellar wind; results support the picture of strong wind clumping. In high-mass X-ray binaries, the stochastic X-ray variability and the extend of the stellar-wind part photoionized by X-rays provide further strong evidence that stellar winds consist of dense clumps.

  6. Chandra X-ray Observatory Center

    E-print Network

    Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St's Chandra X-ray Observatory and ESA's XMM-Newton. A specially processed Chandra image (pink) has been years) Chandra X-ray Observatory ACIS Image CXC operated for NASA by the Smithsonian Astrophysical

  7. Chandra X-ray Observatory Center

    E-print Network

    Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St, & the Hubble Heritage Team (STScI/AURA) Caption: This composite image from the Chandra X-ray Observatory (blue: Image is 1.6 arcmin across (about 100,000 light years) Chandra X-ray Observatory ACIS Image CXC operated

  8. Chandra X-ray Observatory Center

    E-print Network

    Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St. Cambridge, MA 02138 USA http://chandra.harvard.edu Four Supernova Remnants: NASA's Chandra X-ray Observatory's Chandra X-ray Observatory, four newly processed images of supernova remnants dramatically illustrate

  9. Optical coherence tomography can assess skeletal muscle tissue from mouse models of muscular dystrophy by parametric imaging of the attenuation coefficient

    PubMed Central

    Klyen, Blake R.; Scolaro, Loretta; Shavlakadze, Tea; Grounds, Miranda D.; Sampson, David D.

    2014-01-01

    We present the assessment of ex vivo mouse muscle tissue by quantitative parametric imaging of the near-infrared attenuation coefficient µt using optical coherence tomography. The resulting values of the local total attenuation coefficient µt (mean ± standard error) from necrotic lesions in the dystrophic skeletal muscle tissue of mdx mice are higher (9.6 ± 0.3 mm?1) than regions from the same tissue containing only necrotic myofibers (7.0 ± 0.6 mm?1), and significantly higher than values from intact myofibers, whether from an adjacent region of the same sample (4.8 ± 0.3 mm?1) or from healthy tissue of the wild-type C57 mouse (3.9 ± 0.2 mm?1) used as a control. Our results suggest that the attenuation coefficient could be used as a quantitative means to identify necrotic lesions and assess skeletal muscle tissue in mouse models of human Duchenne muscular dystrophy. PMID:24761302

  10. X-ray tube-based diffraction enhanced imaging prototype images of full-thickness breast specimens: reader study evaluation

    Microsoft Academic Search

    L. S. Faulconer; C. Parham; D. J. Connor; M. Koomen; C. Kuzmiak; D. Pavic; C. A. Livasy; E. Kim; D. Zeng; E. B. Cole; Z. Zhong; E. D. Pisano

    2009-01-01

    Conventional mammographic image contrast is derived from x-ray absorption, resulting in breast structure visualization due to density gradients that attenuate radiation without distinction between transmitted and scattered or refracted x-rays. This leads to image blurring and contrast reduction, hindering the early detection of small or otherwise occult cancers. Diffraction enhanced imaging (DEI) allows for dramatically increased contrast with decreased radiation

  11. Near optimal energy selective x-ray imaging system performance with simple detectors

    PubMed Central

    Alvarez, Robert E.

    2010-01-01

    Purpose: This article describes a method to achieve near optimal performance with low energy resolution detectors. Tapiovaara and Wagner [Phys. Med. Biol. 30, 519–529 (1985)] showed that an energy selective x-ray system using a broad spectrum source can produce images with a larger signal to noise ratio (SNR) than conventional systems using energy integrating or photon counting detectors. They showed that there is an upper limit to the SNR and that it can be achieved by measuring full spectrum information and then using an optimal energy dependent weighting. Methods: A performance measure is derived by applying statistical detection theory to an abstract vector space of the line integrals of the basis set coefficients of the two function approximation to the x-ray attenuation coefficient. The approach produces optimal results that utilize all the available energy dependent data. The method can be used with any energy selective detector and is applied not only to detectors using pulse height analysis (PHA) but also to a detector that simultaneously measures the total photon number and integrated energy, as discussed by Roessl et al. [Med. Phys. 34, 959–966 (2007)]. A generalization of this detector that improves the performance is introduced. A method is described to compute images with the optimal SNR using projections in a “whitened” vector space transformed so the noise is uncorrelated and has unit variance in both coordinates. Material canceled images with optimal SNR can also be computed by projections in this space. Results: The performance measure is validated by showing that it provides the Tapiovaara–Wagner optimal results for a detector with full energy information and also a conventional detector. The performance with different types of detectors is compared to the ideal SNR as a function of x-ray tube voltage and subject thickness. A detector that combines two bin PHA with a simultaneous measurement of integrated photon energy provides near ideal performance across a wide range of operating conditions. Conclusions: Low energy resolution detectors can be used in energy selective x-ray imaging systems to produce images with near optimal performance. PMID:20229892

  12. Near optimal energy selective x-ray imaging system performance with simple detectors

    SciTech Connect

    Alvarez, Robert E. [Aprend Technology, Mountain View, California 94043 (United States)

    2010-02-15

    Purpose: This article describes a method to achieve near optimal performance with low energy resolution detectors. Tapiovaara and Wagner [Phys. Med. Biol. 30, 519-529 (1985)] showed that an energy selective x-ray system using a broad spectrum source can produce images with a larger signal to noise ratio (SNR) than conventional systems using energy integrating or photon counting detectors. They showed that there is an upper limit to the SNR and that it can be achieved by measuring full spectrum information and then using an optimal energy dependent weighting. Methods: A performance measure is derived by applying statistical detection theory to an abstract vector space of the line integrals of the basis set coefficients of the two function approximation to the x-ray attenuation coefficient. The approach produces optimal results that utilize all the available energy dependent data. The method can be used with any energy selective detector and is applied not only to detectors using pulse height analysis (PHA) but also to a detector that simultaneously measures the total photon number and integrated energy, as discussed by Roessl et al. [Med. Phys. 34, 959-966 (2007)]. A generalization of this detector that improves the performance is introduced. A method is described to compute images with the optimal SNR using projections in a ''whitened'' vector space transformed so the noise is uncorrelated and has unit variance in both coordinates. Material canceled images with optimal SNR can also be computed by projections in this space. Results: The performance measure is validated by showing that it provides the Tapiovaara-Wagner optimal results for a detector with full energy information and also a conventional detector. The performance with different types of detectors is compared to the ideal SNR as a function of x-ray tube voltage and subject thickness. A detector that combines two bin PHA with a simultaneous measurement of integrated photon energy provides near ideal performance across a wide range of operating conditions. Conclusions: Low energy resolution detectors can be used in energy selective x-ray imaging systems to produce images with near optimal performance.

  13. X-ray spectroscopy of low-mass X-ray binaries

    E-print Network

    Juett, Adrienne Marie, 1976-

    2004-01-01

    I present high-resolution X-ray grating spectroscopy of neutron stars in low-mass X-ray binaries (LMXBs) using instruments onboard the Chandra X-ray Observatory and the X-ray Multi-Mirror Mission (XMM-Newton). The first ...

  14. Irradiance attenuation coefficient in a stratified ocean - A local property of the medium

    NASA Technical Reports Server (NTRS)

    Gordon, H. R.

    1980-01-01

    The influence of optically important constituents of water on the absorption (a) and scattering (b) coefficients and the backscattering probability is considered, with emphasis placed on measuring the volume scattering function (B/theta/). Two stratification models are examined; one in which the phase function (B(theta)/b) is depth independent and only b/c is allowed to vary with optical depth, and the other in which both b/c and the phase function depend on depth. The results demonstrate that Gordon's (1977) technique of estimating a and b is applicable without change to a stratified ocean.

  15. Coated x-ray filters

    DOEpatents

    Steinmeyer, P.A.

    1992-11-24

    A radiation filter for filtering radiation beams of wavelengths within a preselected range of wavelengths comprises a radiation transmissive substrate and an attenuating layer deposited on the substrate. The attenuating layer may be deposited by a sputtering process or a vacuum process. Beryllium may be used as the radiation transmissive substrate. In addition, a second radiation filter comprises an attenuating layer interposed between a pair of radiation transmissive layers. 4 figs.

  16. X-ray imaging for palaeontology.

    PubMed

    Hohenstein, P

    2004-05-01

    Few may be aware that X-ray imaging is used in palaeontology and has been used since as early as 1896. The X-raying, preparation and exposure of Hunsrück slate fossils are described. Hospital X-ray machines are used by the author in his work. An X-ray is vital to provide evidence that preparation of a slate is worthwhile as well as to facilitate preparation even if there is little external sign of what lies within. The beauty of the X-ray exposure is an added bonus. PMID:15121706

  17. Atmospheric electron x-ray spectrometer

    NASA Technical Reports Server (NTRS)

    Feldman, Jason E. (Inventor); George, Thomas (Inventor); Wilcox, Jaroslava Z. (Inventor)

    2002-01-01

    The present invention comprises an apparatus for performing in-situ elemental analyses of surfaces. The invention comprises an atmospheric electron x-ray spectrometer with an electron column which generates, accelerates, and focuses electrons in a column which is isolated from ambient pressure by a:thin, electron transparent membrane. After passing through the membrane, the electrons impinge on the sample in atmosphere to generate characteristic x-rays. An x-ray detector, shaping amplifier, and multi-channel analyzer are used for x-ray detection and signal analysis. By comparing the resultant data to known x-ray spectral signatures, the elemental composition of the surface can be determined.

  18. X-ray holography of biological specimens

    SciTech Connect

    Solem, J.C.

    1984-01-01

    The author reviews the reasons for x-ray imaging of biological specimens and the techniques presently being used for x-ray microscopy. The author points out the advantages of x-ray holography and the difficulties of obtaining the requisite coherence with conventional sources. The author discusses the problems of radiation damage and the remarkable fact that short pulse x-ray sources circumvent these problems and obtain high-resolution images of specimens in the living state. Finally, the author reviews some of the efforts underway to develop high-intensity coherent x-ray sources for the laboratory. 14 references, 5 figures, 2 tables.

  19. X-ray Spectroscopy of Cooling Cluster

    SciTech Connect

    Peterson, J.R.; /SLAC; Fabian, A.C.; /Cambridge U., Inst. of Astron.

    2006-01-17

    We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

  20. X-ray spectrum sampling technology in the CT projection simulation

    Microsoft Academic Search

    Fanglin Chen; Ping Chen; Yan Han; Jinxiao Pan

    2010-01-01

    A computer code was developed to simulate the operation of radioscopic or tomographic devices. The simulation is based on ray-tracing techniques and on the X-ray attenuation law. However, in the process of projection simulation, we can’t use an expression to describe the distribution of the consecutive X-ray spectrum which is simulated by the Monte Carlo method. We only use numerical

  1. Three-dimensional characterization of electrodeposited lithium microstructures using synchrotron X-ray phase contrast imaging.

    PubMed

    Eastwood, David S; Bayley, Paul M; Chang, Hee Jung; Taiwo, Oluwadamilola O; Vila-Comamala, Joan; Brett, Daniel J L; Rau, Christoph; Withers, Philip J; Shearing, Paul R; Grey, Clare P; Lee, Peter D

    2015-01-01

    The electrodeposition of metallic lithium is a major cause of failure in lithium batteries. The 3D microstructure of electrodeposited lithium 'moss' in liquid electrolytes has been characterised at sub-micron resolution for the first time. Using synchrotron X-ray phase contrast imaging we distinguish mossy metallic lithium microstructures from high surface area lithium salt formations by their contrasting X-ray attenuation. PMID:24898258

  2. Computerized X-ray tomography analysis of sandbox models: Examples of thin-skinned thrust systems

    Microsoft Academic Search

    Bernard Colletta; Jean Letouzey; Roberto Pinedo; Jean François Ballard; Pascal Balé

    1991-01-01

    Computerized X-ray tomography applied to analog sandbox experiments performed in a normal gravity field makes possible the analysis of the kinematic evolution, as well as the three-dimensional geometry, of models that simulate tectonic deformations. Most of the plastic or viscous analog materials generally used in a normal gravity field for such models have X-ray attenuations compatible with medical scanner images.

  3. X-ray lithography using holographic images

    DOEpatents

    Howells, Malcolm R. (Berkeley, CA); Jacobsen, Chris (Sound Beach, NY)

    1995-01-01

    A non-contact X-ray projection lithography method for producing a desired X-ray image on a selected surface of an X-ray-sensitive material, such as photoresist material on a wafer, the desired X-ray image having image minimum linewidths as small as 0.063 .mu.m, or even smaller. A hologram and its position are determined that will produce the desired image on the selected surface when the hologram is irradiated with X-rays from a suitably monochromatic X-ray source of a selected wavelength .lambda.. On-axis X-ray transmission through, or off-axis X-ray reflection from, a hologram may be used here, with very different requirements for monochromaticity, flux and brightness of the X-ray source. For reasonable penetration of photoresist materials by X-rays produced by the X-ray source, the wavelength X, is preferably chosen to be no more than 13.5 nm in one embodiment and more preferably is chosen in the range 1-5 nm in the other embodiment. A lower limit on linewidth is set by the linewidth of available microstructure writing devices, such as an electron beam.

  4. The Rosat x-ray sky

    NASA Astrophysics Data System (ADS)

    Voges, Wolfgang

    1995-01-01

    The ROSAT (Röntgensatellit) X-ray astronomy satellite has completed the first all-sky x-ray and XUV survey with imaging telescopes. About 60 000 new x-ray and 400 new XUV (1) sources were detected. This contribution will deal with preliminary results from the ROSAT ALL-SKY X-RAY SURVEY. The ROSAT diffuse and point-source x-ray skymaps, the positional accuracy obtained for the x-ray sources, and a few results from correlations performed with available catalogues in various energy bands like the Radio, Infrared, Visible, UV, and hard x-rays as well as identifications from optical follow-up observations will be presented.

  5. X ray imaging microscope for cancer research

    NASA Technical Reports Server (NTRS)

    Hoover, Richard B.; Shealy, David L.; Brinkley, B. R.; Baker, Phillip C.; Barbee, Troy W., Jr.; Walker, Arthur B. C., Jr.

    1991-01-01

    The NASA technology employed during the Stanford MSFC LLNL Rocket X Ray Spectroheliograph flight established that doubly reflecting, normal incidence multilayer optics can be designed, fabricated, and used for high resolution x ray imaging of the Sun. Technology developed as part of the MSFC X Ray Microscope program, showed that high quality, high resolution multilayer x ray imaging microscopes are feasible. Using technology developed at Stanford University and at the DOE Lawrence Livermore National Laboratory (LLNL), Troy W. Barbee, Jr. has fabricated multilayer coatings with near theoretical reflectivities and perfect bandpass matching for a new rocket borne solar observatory, the Multi-Spectral Solar Telescope Array (MSSTA). Advanced Flow Polishing has provided multilayer mirror substrates with sub-angstrom (rms) smoothnesss for the astronomical x ray telescopes and x ray microscopes. The combination of these important technological advancements has paved the way for the development of a Water Window Imaging X Ray Microscope for cancer research.

  6. The Universe in X-rays

    NASA Astrophysics Data System (ADS)

    Henbest, N.

    1982-03-01

    Various programs and discoveries of X-ray astronomy from space-based instruments are reviewed. The first X-ray object discovered was Sco X-1 during a rocket flight in 1962. The Uhuru satellite identified dozens of X-ray sources, including Cyg X-1, which is a possible black hole. The HEAO-1 satellite carried detectors large enough to permit some resolution of the X-ray sources. X-ray telescopes were used on Skylab and on HEAO-2, employing a parabolic mirror at the aperture followed by a hyperbolic mirror which focused the original image onto a detector. The HEAO-2, also known as the Einstein Observatory, allowed discovery of a number of quasars. The X-ray telescope satellites Copernicus, Einstein, and Ariel VI were successively shut down, leaving only the Japanese spacecraft Hakucho detecting burster events. Future X-ray observing satellites such as AXAF, Exosat, and Rosat are outlined.

  7. Evolution of x-ray astronomy

    SciTech Connect

    Rossj, B.

    1981-01-01

    The evolution of X-ray astronomy up to the launching of the Einstein observatory is presented. The evaluation proceeded through the following major steps: (1) discovery of an extrasolar X-ray source, Sco X-1, orders of magnitude stronger than astronomers believed might exist (2) identification of a strong X-ray source with the Crab Nebula (3) identification of Sco X-1 with a faint, peculiar optical object (4) demonstration that X-ray stars are binary systems, each consisting of a collapsed object accreting matter from an ordinary star (5) discovery of X-ray bursts (6) discovery of exceedingly strong X-ray emission from active galaxies, quasars and clusters of galaxies (7) demonstration that the principal X-ray source is a hot gas filling the space between galaxies.

  8. The AAPM/RSNA physics tutorial for residents. X-ray interactions.

    PubMed

    Bushberg, J T

    1998-01-01

    The diagnostic information in a radiograph or fluoroscopic image is largely the result of the quantity of x rays that are not removed from the incident x-ray beam. The information content of the image is delivered by the percentage of noninteracting photons that are successfully recorded. There are four major x-ray interactions: Rayleigh (coherent) scattering. Compton scattering, photoelectric absorption, and pair production. The degree of attenuation and the predominant mechanisms involved in the interactions are influenced by the x-ray energy and tissue composition. In the diagnostic energy range, photoelectric absorption and Compton scattering are the predominant modes of attenuation. One of the challenges in diagnostic imaging is to optimize image acquisition by controlling x-ray attenuation to obtain the appropriate contrast between the tissues while minimizing patient dose and scattered radiation in the image. Imaging techniques such as use of contrast material and dedicated mammography equipment exploit the differences in these types of x-ray interactions to improve the quality and diagnostic utility of the examination. Rayleigh scattering and pair production are presented but do not occur to any significant degree in diagnostic radiography. PMID:9536489

  9. Utilization of nanoparticles as X-ray contrast agents for diagnostic imaging applications.

    PubMed

    De La Vega, José Carlos; Häfeli, Urs O

    2015-01-01

    Among all the diagnostic imaging modalities, X-ray imaging techniques are the most commonly used owing to their high resolution and low cost. The improvement of these techniques relies heavily on the development of novel X-ray contrast agents, which are molecules that enhance the visibility of internal structures within the body in X-ray imaging. To date, clinically used X-ray contrast agents consist mainly of small iodinated molecules that might cause severe adverse effects (e.g.?allergies, cardiovascular diseases and nephrotoxicity) in some patients owing to the large and repeated doses that are required to achieve good contrast. For this reason, there is an increasing interest in the development of alternative X-ray contrast agents utilizing elements with high atomic numbers (e.g.?gold, bismuth, ytterbium and tantalum), which are well known for exhibiting high absorption of X-rays. Nanoparticles (NPs) made from these elements have been reported to have better imaging properties, longer blood circulation times and lower toxicity than conventional iodinated X-ray contrast agents. Additionally, the combination of two or more of these elements into a single carrier allows for the development of multimodal and hybrid contrast agents. Herein, the limitations of iodinated X-ray contrast agents are discussed and the parameters that influence the efficacy of X-ray contrast agents are summarized. Several examples of the design and production of both iodinated and iodine-free NP-based X-ray contrast agents are then provided, emphasizing the studies performed to evaluate their X-ray attenuation capabilities and their toxicity in vitro and in vivo. PMID:25044541

  10. X-ray phase-contrast tomography with a compact laser-driven synchrotron source.

    PubMed

    Eggl, Elena; Schleede, Simone; Bech, Martin; Achterhold, Klaus; Loewen, Roderick; Ruth, Ronald D; Pfeiffer, Franz

    2015-05-01

    Between X-ray tubes and large-scale synchrotron sources, a large gap in performance exists with respect to the monochromaticity and brilliance of the X-ray beam. However, due to their size and cost, large-scale synchrotrons are not available for more routine applications in small and medium-sized academic or industrial laboratories. This gap could be closed by laser-driven compact synchrotron light sources (CLS), which use an infrared (IR) laser cavity in combination with a small electron storage ring. Hard X-rays are produced through the process of inverse Compton scattering upon the intersection of the electron bunch with the focused laser beam. The produced X-ray beam is intrinsically monochromatic and highly collimated. This makes a CLS well-suited for applications of more advanced--and more challenging--X-ray imaging approaches, such as X-ray multimodal tomography. Here we present, to our knowledge, the first results of a first successful demonstration experiment in which a monochromatic X-ray beam from a CLS was used for multimodal, i.e., phase-, dark-field, and attenuation-contrast, X-ray tomography. We show results from a fluid phantom with different liquids and a biomedical application example in the form of a multimodal CT scan of a small animal (mouse, ex vivo). The results highlight particularly that quantitative multimodal CT has become feasible with laser-driven CLS, and that the results outperform more conventional approaches. PMID:25902493

  11. Plasma-driven Z-pinch X-ray loading and momentum coupling in meteorite and planetary materials

    NASA Astrophysics Data System (ADS)

    Remo, John L.; Furnish, Michael D.; Lawrence, R. Jeffery; Lawrence

    2013-04-01

    X-ray momentum coupling coefficients, C M, were determined by measuring stress waveforms in planetary materials subjected to impulsive radiation loading from the Sandia National Laboratories Z-machine. Velocity interferometry (VISAR) diagnostics provided equation-of-state data. Targets were iron and stone meteorites, magnesium-rich olivine (dunite) solid and powder (~5-300 ?m), and Si, Al, and Fe calibration targets. Samples were ~1-mm thick and, except for Si, backed by LiF single-crystal windows. X-ray spectra combined thermal radiation (blackbody 170-237 eV) and line emissions from pinch materials (Cu, Ni, Al, or stainless steel). Target fluences of 0.4-1.7 kJ/cm2 at intensities of 43-260GW/cm2 produced plasma pressures of 2.6-12.4 GPa. The short (~5 ns) drive pulses gave rise to attenuating stress waves in the samples. The attenuating wave impulse is constant, allowing accurate C M measurements from rear-surface motion. C M was 1.9 - 3.1 × 10-5 s/m for stony meteorites, 2.7 and 0.5 × 10-5 s/m for solid and powdered dunite, 0.8 - 1.4 × 10-5 s/m for iron meteorites, and 0.3, 1.8, and 2.7 × 10-5 s/m respectively for Si, Fe, and Al calibration targets. Results are consistent with geometric scaling from recent laser hohlraum measurements. CTH hydrocode modeling of X-ray coupling to porous silica corroborated experimental measurements and supported extrapolations to other materials. CTH-modeled C M for porous materials was low and consistent with experimental results. Analytic modeling (BBAY) of X-ray radiation-induced momentum coupling to selected materials was also performed, often producing higher C M values than experimental results. Reasons for the higher values include neglect of solid ejecta mechanisms, turbulent mixing of heterogeneous phases, variances in heats of melt/vaporization, sample inhomogeneities, wave interactions at the sample/window boundary, and finite sample/window sizes. The measurements validate application of C M to (inhomogeneous) planetary materials from high-intensity soft X-ray radiation.

  12. Collimator for an x-ray mammography apparatus

    Microsoft Academic Search

    1989-01-01

    A device for generating collimated X-ray beams is described, the device comprising: an X-ray source for emitting an input X-ray beam; a cone arranged in the input X-ray beam to receive the entire input X-ray beam, the cone blocking a portion of the input X-ray beam such that a limited output X-ray beam emerges from the cone, the output X-ray

  13. Soft x-ray shock loading and momentum coupling in meteorite and planetary materials.

    SciTech Connect

    Lawrence, R. Jeffery; Remo, John L. (Harvard University, Cambridge, MA); Furnish, Michael David

    2010-12-01

    X-ray momentum coupling coefficients, C{sub M}, were determined by measuring stress waveforms in planetary materials subjected to impulsive radiation loading from the Sandia National Laboratories Z-machine. Results from the velocity interferometry (VISAR) diagnostic provided limited equation-of-state data as well. Targets were iron and stone meteorites, magnesium rich olivine (dunite) solid and powder ({approx}5--300 {mu}m), and Si, Al, and Fe calibration targets. All samples were {approx}1 mm thick and, except for Si, backed by LiF single-crystal windows. The x-ray spectrum included a combination of thermal radiation (blackbody 170--237 eV) and line emissions from the pinch material (Cu, Ni, Al, or stainless steel). Target fluences 0.4--1.7 kJ/cm{sup 2} at intensities 43--260 GW/cm{sup 2} produced front surface plasma pressures 2.6--12.4 GPa. Stress waves driven into the samples were attenuating due to the short ({approx}5 ns) duration of the drive pulse. Attenuating wave impulse is constant allowing accurate C{sub M} measurements provided mechanical impedance mismatch between samples and the window are known. Impedance-corrected C{sub M} determined from rear-surface motion was 1.9--3.1 x 10{sup -5} s/m for stony meteorites, 2.7 and 0.5 x 10{sup -5} s/m for solid and powdered dunite, 0.8--1.4 x 10{sup -5}.

  14. X-ray observations of Be stars

    NASA Technical Reports Server (NTRS)

    Rappaport, S.; Van Den Heuvel, E. P. J.

    1982-01-01

    Be star binaries with neutron star companions are shown to constitute a major class of X-ray sources. Some general observational and interpretive techniques of X-ray astronomy are reviewed. Data for 12 Be/X-ray binary systems are summarized. The Be/X-ray binaries are found to be systematically wider systems, with lower-mass primaries, and with significantly more transient behavior than the 'standard' massive X-ray binaries such as Cen X-3 and SMC X-1. The difference between the two types of X-ray binaries is explained in the context of slightly different evolutionary scenarios for the progenitor binaries. The 'standard' massive X-ray binaries result from wind-mass-loss dominated evolution of very massive close binaries, while Be/X-ray binaries probably result from mass-transfer dominated evolution of systems with primary masses less than approximately 20 solar masses. The implications of the X-ray observations of Be/X-ray binaries for Be stars in general are discussed.

  15. X-ray omni microscopy.

    PubMed

    Paganin, D; Gureyev, T E; Mayo, S C; Stevenson, A W; Nesterets, Ya I; Wilkins, S W

    2004-06-01

    The science of wave-field phase retrieval and phase measurement is sufficiently mature to permit the routine reconstruction, over a given plane, of the complex wave-function associated with certain coherent forward-propagating scalar wave-fields. This reconstruction gives total knowledge of the information that has been encoded in the complex wave-field by passage through a sample of interest. Such total knowledge is powerful, because it permits the emulation in software of the subsequent action of an infinite variety of coherent imaging systems. Such 'virtual optics', in which software forms a natural extension of the 'hardware optics' in an imaging system, may be useful in contexts such as quantitative atom and X-ray imaging, in which optical elements such as beam-splitters and lenses can be realized in software rather than optical hardware. Here, we develop the requisite theory to describe such hybrid virtual-physical imaging systems, which we term 'omni optics' because of their infinite flexibility. We then give an experimental demonstration of these ideas by showing that a lensless X-ray point projection microscope can, when equipped with the appropriate software, emulate an infinite variety of optical imaging systems including those which yield interferograms, Zernike phase contrast, Schlieren imaging and diffraction-enhanced imaging. PMID:15157198

  16. Transportable X-ray cart

    SciTech Connect

    NONE

    1995-12-01

    The main body of the report summarizes the project scope, project milestones, highlights any unresolved problems encountered during the project and includes a summary of the financial information. The purpose of this CRADA was to assist Digiray Corporation in the development and evaluation of a Transportable Reverse Geometry X-Ray 0 (RGX-T) cart for aircraft inspection Scope: LLNL was to provide a review of the RGX-T engineering drawing package supplied by Digiray, suggest and incorporate design modifications, fabricate, assemble and provide performance evaluation testing of the RGX-T prototype. Major deliverables were (a) engineering design analysis and evaluation (b) cart prototype hardware, and (c) performance evaluation. Schedule: Procurement and technical delays extended the project twelve months past than the original four month project duration estimate. LLNL reviewed engineering drawings of the RGX-T prototype provided by Digiray, performed a engineering design analysis and evaluation, suggested and incorporated modifications to improve design safety factors, fabricated and assembled the prototype system, and evaluated the motion and positioning capabilities of the assembled system. The RGX-T provides a limited set of positioning orientations for the Digiray x-ray tube head that do not meet the overall Digiray requirements for aircraft inspection. In addition, mechanical stability concerns remain for positioning the tube head with the mechanical arm and for rolling the assembly with arbitrary orientation of the mechanical arm.

  17. Towards a quantitative, measurement-based estimate of the uncertainty in photon mass attenuation coefficients at radiation therapy energies

    NASA Astrophysics Data System (ADS)

    Ali, E. S. M.; Spencer, B.; McEwen, M. R.; Rogers, D. W. O.

    2015-02-01

    In this study, a quantitative estimate is derived for the uncertainty in the XCOM photon mass attenuation coefficients in the energy range of interest to external beam radiation therapy—i.e. 100 keV (orthovoltage) to 25 MeV—using direct comparisons of experimental data against Monte Carlo models and theoretical XCOM data. Two independent datasets are used. The first dataset is from our recent transmission measurements and the corresponding EGSnrc calculations (Ali et al 2012 Med. Phys. 39 5990–6003) for 10–30 MV photon beams from the research linac at the National Research Council Canada. The attenuators are graphite and lead, with a total of 140 data points and an experimental uncertainty of ˜0.5% (k = 1). An optimum energy-independent cross section scaling factor that minimizes the discrepancies between measurements and calculations is used to deduce cross section uncertainty. The second dataset is from the aggregate of cross section measurements in the literature for graphite and lead (49 experiments, 288 data points). The dataset is compared to the sum of the XCOM data plus the IAEA photonuclear data. Again, an optimum energy-independent cross section scaling factor is used to deduce the cross section uncertainty. Using the average result from the two datasets, the energy-independent cross section uncertainty estimate is 0.5% (68% confidence) and 0.7% (95% confidence). The potential for energy-dependent errors is discussed. Photon cross section uncertainty is shown to be smaller than the current qualitative ‘envelope of uncertainty’ of the order of 1–2%, as given by Hubbell (1999 Phys. Med. Biol 44 R1–22).

  18. Towards a quantitative, measurement-based estimate of the uncertainty in photon mass attenuation coefficients at radiation therapy energies.

    PubMed

    Ali, E S M; Spencer, B; McEwen, M R; Rogers, D W O

    2015-02-21

    In this study, a quantitative estimate is derived for the uncertainty in the XCOM photon mass attenuation coefficients in the energy range of interest to external beam radiation therapy-i.e. 100 keV (orthovoltage) to 25 MeV-using direct comparisons of experimental data against Monte Carlo models and theoretical XCOM data. Two independent datasets are used. The first dataset is from our recent transmission measurements and the corresponding EGSnrc calculations (Ali et al 2012 Med. Phys. 39 5990-6003) for 10-30 MV photon beams from the research linac at the National Research Council Canada. The attenuators are graphite and lead, with a total of 140 data points and an experimental uncertainty of ?0.5% (k = 1). An optimum energy-independent cross section scaling factor that minimizes the discrepancies between measurements and calculations is used to deduce cross section uncertainty. The second dataset is from the aggregate of cross section measurements in the literature for graphite and lead (49 experiments, 288 data points). The dataset is compared to the sum of the XCOM data plus the IAEA photonuclear data. Again, an optimum energy-independent cross section scaling factor is used to deduce the cross section uncertainty. Using the average result from the two datasets, the energy-independent cross section uncertainty estimate is 0.5% (68% confidence) and 0.7% (95% confidence). The potential for energy-dependent errors is discussed. Photon cross section uncertainty is shown to be smaller than the current qualitative 'envelope of uncertainty' of the order of 1-2%, as given by Hubbell (1999 Phys. Med. Biol 44 R1-22). PMID:25622289

  19. Gamma Ray Attenuation Coefficient Measurement in Energies 1172 keV and 1332 keV for Neutron Absorbent Saturated Solutions

    SciTech Connect

    Jalali, Majid [Esfahan Nuclear Technology Center - ENTC (Iran, Islamic Republic of)

    2006-07-01

    The compounds, Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions, attenuate gamma rays in addition to neutron absorption. These compounds are widely used in shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to saturated solutions of the above four compounds, in energies 1172 keV and 1332 keV have been measured by NaI detector and agree very well with the results obtained by Xcom code. Experiment and computation show that, H{sub 3}BO{sub 3} has the highest gamma ray attenuation coefficient among the aforementioned compounds. (author)

  20. Applications of x rays in art authentication: radiography, x-ray diffraction, and x-ray fluorescence

    Microsoft Academic Search

    Richard Newman

    1998-01-01

    Several techniques involving X-rays are routinely applied in the study of works of art. These include radiography, X-ray diffraction, and X-ray fluorescence (often coupled with an electron beam instrument such as a scanning electron microscope or microprobe). Radiography provides information on condition and previous restorations or repairs. In the case of sculptures, the technique also sheds light on the manufacturing

  1. Internal-conversion process in superintense ultrashort x-ray pulses

    SciTech Connect

    Kis, Daniel; Kalman, Peter; Keszthelyi, Tamas; Szivos, Janos [Budapest University of Technology and Economics, Institute of Nuclear Technics, Department of Nuclear Energy, Muegyetem rkpt. 9, H-1111 Budapest (Hungary); Budapest University of Technology and Economics, Institute of Physics, Department of Theoretical Physics, Budafoki ut 8. F. I. I. 10, H-1521 Budapest (Hungary)

    2010-01-15

    The electron-nucleus interaction in a super-intense few-cycle x-ray pulse is investigated. The super-intense few-cycle x-ray pulse-induced internal conversion (IC) process is discussed in detail. The x-ray laser-pulse induced IC coefficient is calculated, and in particular, it is derived in the case of a pulse of Gaussian shape and for a bound-free electron transition. The IC coefficient of the IC process induced by a super-intense few-cycle soft-x-ray laser pulse in the case of the {sup 99m}Tc isomer is determined numerically. The results obtained for the IC coefficient show significant carrier angular frequency, carrier-envelope phase, and pulse-length dependencies. The infinite pulse-length limit and experimental aspects are also discussed.

  2. Novel space communication technology based on modulated x-ray source

    NASA Astrophysics Data System (ADS)

    Sheng, Li-zhi; Zhao, Bao-sheng; Liu, Yong-an

    2014-09-01

    A novel space communication method is presented in this paper based on X-ray photons. As a result of its short wavelength and great penetrability, X-ray has no attenuation for transmission in space when its photon energy is more than 10keV (?<0.1nm). Thus a communication technology of long distance signal transmission in space can be achieved with smaller volume, lower weight and lower power. Therefore, X-ray communication (XCOM) is especially valuable to the deep space missions, which will be able to realize higher data rates, smaller SWAP than with RF and laser communications. Using X-ray photons as information carrier will not only be a good complement to laser and RF communications, but will also have unique applications when RF and laser signals are not available like the spacecraft's re-entering to the earth. High-speed modulation and high-sensitivity detection of X-rays are two major technical issues which should be addressed in order for the X-ray communication to take place. A Grid-controlled Modulated X-ray tube (GMXT) is proposed and developed as X-ray transmitter. One or more specially designed grid electrodes are added to the traditional X-ray tube to modulate the electrons. The communication signal is coded and applied to the modulated grid electrode, and then the corresponding X-ray signals are generated and sent out. X-ray detector based on micro-channel plate(MCP) is used as communication receiver because of its high temporal resolution. An audio communication experiment system based on XCOM is setup in laboratory including the X-ray transmitter and the receiver. X-ray communication is successfully demonstrated and the communication speed reaches 64 kilobits per second in a vacuum tube of 6 meters long. As a new concept of space communication, X-ray communication will have more important scientific significance and application prospects when technologies for X-ray modulation and detection are further developed.

  3. Martin Elvis, X-ray & XUV Active Optics, Soleil, 14-15 Dec 2006 Active X-ray OpticsActive X-ray Optics

    E-print Network

    Elvis, Martin

    1 Martin Elvis, X-ray & XUV Active Optics, Soleil, 14-15 Dec 2006 Active X-ray OpticsActive X-ray Optics For The Next High Resolution X-ray Observatory Martin Elvis Harvard-Smithsonian Center for Astrophysics Cambridge, Massachusetts, USA #12;2 Martin Elvis, X-ray & XUV Active Optics, Soleil, 14-15 Dec

  4. Dosimetry of a low-kV intra-operative X-ray source using basic analytical beam models.

    PubMed

    Ebert, M A; Carruthers, B; Lanzon, P J; Haworth, A; Clarke, J; Caswell, N M; Siddiqui, S A

    2002-09-01

    The low energy (30-50 kVp) beams from an intra-operative X-ray source are modelled using a basic analytical model considering just primary beam attenuation and absorption. Spatial dosimetry at such low energies is difficult due to the rapid changes in dose-rate from the radiation source. The purpose of the model was to determine the variation with distance in water of coefficients required for beam dosimetry and to validate beam measurements performed in water of high-gradient dose distributions. The model predicts a change in mean mass-energy absorption coefficient of up to 3 % over the range of clinically-relevant distances in water. Distance-dose distributions (variation in dose with distance in water) for the X-ray source were calculated with the model and found to be in agreement with measurement (at clinically-relevant distances), to within a spatial distance comparable to the dimensions and positional accuracy of the ionization chamber used, and comparable to the expected dosimetric anisotropy of the radiation source. Measured and calculated distance-doses begin to diverge at relatively large distances from the radiation source, which is where dose-rates are so low that detector signal levels are comparable with noise. PMID:12416588

  5. X-ray laser frequency near-doubling and generation of tunable coherent x rays in plasma

    E-print Network

    Kaplan, Alexander

    X-ray laser frequency near-doubling and generation of tunable coherent x rays in plasma P. L plasmas in which efficient x-ray laser frequency near-doubling is expected for a number of available x-ray of coherent x rays and tunable optical radiation may result in tunable coherent x-ray radiation powerful

  6. X-rays from Massive StarsX-rays from Massive Stars David CohenDavid Cohen

    E-print Network

    Cohen, David

    X-rays from Massive StarsX-rays from Massive Stars David CohenDavid Cohen Swarthmore CollegeSwarthmore College #12;X-ray spectroscopy of hot plasmasX-ray spectroscopy of hot plasmas temperature, density: shock-heating and X-ray emissionshock-heating and X-ray emission with Stan Owocki (U. Del.)with Stan

  7. Atomic physics modeling of x-ray laser plasmas

    SciTech Connect

    Osterheld, A.L.; Young, B.K.F.; Walling, R.S.; Goldstein, W.H.; Scofield, J.H.; Chen, M.; Shimkaveg, G.; Carter, M.; Shepherd, R.; MacGowan, B.J.; Da Silva, L.; Matthews, D.; Maxon, S.; London, R.; Stewart, R.E.

    1992-05-01

    We have developed collisional-radiative models to describe the kinetics of x-ray laser plasmas. Careful attention has been paid to indirect processes such as dielectronic recombination and excitation-autoionization. These models can be used for calculations of the ionization dynamics, gain coefficients, and detailed emission spectra. We will present results from ionization balance and gain calculations for neonlike and nickellike collisional lasing schemes, emphasizing the effects of different atomic physics processes and model approximations.

  8. Soft x-ray polarimeter laboratory tests

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  9. The ELAIS Deep X-ray Survey

    E-print Network

    C. J. Willott; O. Almaini; J. Manners; O. Johnson; A. Lawrence; J. S. Dunlop; R. G Mann; I. Perez-Fournon; E. Gonzalez-Solares; F. Cabrera-Guerra; S. Serjeant; S. J. Oliver; M. Rowan-Robinson

    2001-05-31

    We present initial follow-up results of the ELAIS Deep X-ray Survey which is being undertaken with the Chandra and XMM-Newton Observatories. 235 X-ray sources are detected in our two 75 ks ACIS-I observations in the well-studied ELAIS N1 and N2 areas. 90% of the X-ray sources are identified optically to R=26 with a median magnitude of R=24. We show that objects which are unresolved optically (i.e. quasars) follow a correlation between their optical and X-ray fluxes, whereas galaxies do not. We also find that the quasars with fainter optical counterparts have harder X-ray spectra, consistent with absorption at both wavebands. Initial spectroscopic follow-up has revealed a large fraction of high-luminosity Type 2 quasars. The prospects for studying the evolution of the host galaxies of X-ray selected Type 2 AGN are considered.

  10. Stimulated electronic x-ray Raman scattering.

    PubMed

    Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A; Bozek, John D; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J; Rohringer, Nina

    2013-12-01

    We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state. PMID:24476271

  11. Time resolved x-ray detection

    NASA Astrophysics Data System (ADS)

    Rentzepis, Peter M.

    1994-04-01

    The goal of the project was to design, develop and construct an x-ray detector with high sensitivity and picosecond time resolution. This was achieved. A Ford Aerospace Charged Coupled Device, CCD, was utilized as the x-ray sensitive material around which the design and construction of the picosecond x-ray detector was built. This device has now become a commercial product sold, among other companies, by Photometrics Inc., and Princeton Research Inc. In addition we designed and built the first picosecond x-ray system. This system was utilized for the first ever picosecond x-ray diffraction experiments. The picosecond x-ray system was utilized in the oxidative fuel cell project to measure the decomposition of methanol and the change of the structure of its platinum catalyst. Another direct product of the work is the publication of 36 papers, in major scientific journals, and two patents.

  12. Large thin adaptive x-ray mirrors

    Microsoft Academic Search

    Peter Doel; Carolyn Atkins; Samantha Thompson; David Brooks; Jun Yao; Charlotte Feldman; Richard Willingale; Tim Button; Dou Zhang; Ady James

    2007-01-01

    This paper describes the progress made in a proof of concept study and recent results of a research program into large active x-ray mirrors that is part of the UK Smart X-ray Optics project. The ultimate aim is to apply the techniques of active\\/adaptive optics to the next generation of nested shell astronomical X-ray space telescopes. A variety of deformable

  13. Optics for X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Catura, R. C.; Joki, E. G.; Vieira, J. R.; Brookover, W. J.

    1986-01-01

    This paper describes a large grazing incidence X-ray telescope that is being prepared for use in a spectrometer for X-ray astronomical observations. The telescope is figured by diamond turning and polished by applying an acrylic lacquer that is overcoated by a thin film of tungsten to provide high X-ray reflectivity. The current status of our research in multilayer deposition is presented and some astronomical applications of multilayer mirrors are described.

  14. The x ray halo of AM Her

    NASA Technical Reports Server (NTRS)

    Catura, Richard C.

    1993-01-01

    The objective of this research was to study the halo surrounding the ROSAT image of the cataclysmic variable AM Her that is formed by scattering of x-rays by interstellar dust grains. AM Her was in a low state of x-ray emission during the 14,400 sec observation and thus an insufficient number of counts were obtained to detect the x-ray halo.

  15. New opportunities in X-ray tomography

    Microsoft Academic Search

    A. G. Peele; H. M. Quiney; B. B. Dhal; A. P. Mancuso; B. Arhatari; K. A. Nugent

    2006-01-01

    We discuss standard X-ray-imaging techniques. Phase-imaging methods and a new class of nano-focus and nano-resolution laboratory systems offer new opportunities in true laboratory-based X-ray microtomography with a host of possible applications that have mainly been demonstrated only at synchrotron sources. Notwithstanding these advances, the diffraction limit for X-ray-imaging methods is a long way off. We preview the link between high-resolution

  16. The X-ray Polarimeter Experiment (XPE)

    Microsoft Academic Search

    R. F. Elsner; B. D. Ramsey; S. L. O'dell; M. Sulkanen; A. F. Tennant; M. C. Weisskopf; S. Gunji; T. Minamitani; R. A. Austin; J. Kolodziejczak; D. Swartz; G. Garmire; P. Meszaros; G. G. Pavlov

    1997-01-01

    Polarimetric studies will provide a new probe of cosmic x-ray sources, supplying important clues to source geometries and emission mechanisms. However, at the present time there is only one measurement of x-ray polarization from a cosmic source, the OSO-8 detection of 19% linear polarization from the Crab Nebula. We propose a new low cost x-ray polarimeter experiment (XPE), ideally sized

  17. A Plethora of X-ray Telescopes

    NSDL National Science Digital Library

    This explanation describes the observatories we are currently using to study X-rays from space. Chandra, named for Nobel prize winner Subrahmanyan Chandrasekhar, was launched from the space shuttle in 1999. Current X-ray observatories include The Rossi X-ray Timing Explorer (RXTE), named after astronomer Bruno Rossi, and The Advanced Satellite for Cosmology and Astrophysics (ASCA). The site also discusses what observatories we will use in the coming years to explore the structure and evolution of the Universe.

  18. X-ray-sensitive CCD camera

    Microsoft Academic Search

    Andrew A. Krasnjuk; Vladimir J. Stenin; Sergey V. Larionov; Victor A. Shilin; Alexander A. Utenkov

    1999-01-01

    This paper describes the key features and performance data of a 1040(H) X 1160(V) pixels full-frame transfer CCD camera for use as an X-ray detector in X-ray material structure analysis and X-ray fluorescence for the in-situ detection of metals. To achieve good sensitivity at energies below 50 keV we have developed compact units based on VLSI programmable logic devices and

  19. Applications of soft x-ray lasers

    SciTech Connect

    Skinner, C.H.

    1993-08-01

    The high brightness and short pulse duration of soft x-ray lasers provide unique advantages for novel applications. Imaging of biological specimens using x-ray lasers has been demonstrated by several groups. Other applications to fields such as chemistry, material science, plasma diagnostics, and lithography are beginning to emerge. We review the current status of soft x-ray lasers from the perspective of applications, and present an overview of the applications currently being developed.

  20. X-ray microlaminography with polycapillary optics

    SciTech Connect

    Dabrowski, K. M.; Dul, D. T.; Wrobel, A.; Korecki, P. [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)] [Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow (Poland)

    2013-06-03

    We demonstrate layer-by-layer x-ray microimaging using polycapillary optics. The depth resolution is achieved without sample or source rotation and in a way similar to classical tomography or laminography. The method takes advantage from large angular apertures of polycapillary optics and from their specific microstructure, which is treated as a coded aperture. The imaging geometry is compatible with polychromatic x-ray sources and with scanning and confocal x-ray fluorescence setups.

  1. Legacy of the X Ray Laser Program

    NASA Astrophysics Data System (ADS)

    Nilsen, J.

    1993-08-01

    The X-Ray Laser Program has evolved from a design effort focusing on developing a Strategic Defense Initiative weapon that protects against Soviet ICBM's to a scientific project that is producing new technologies for industrial and medical research. While the great technical successes and failures of the x-ray laser itself cannot be discussed, this article presents the many significant achievements made as part of the x-ray laser effort that are now being used for other applications at LLNL.

  2. X-ray source for mammography

    Microsoft Academic Search

    Logan; Clinton M

    1994-01-01

    An x-ray source utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5\\/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum

  3. Phase contrast X-ray imaging

    Microsoft Academic Search

    Byung Mook Weon; Jung Ho Je; Yeukuang Hwu

    2006-01-01

    In the last decade X-ray imaging based on phase contrast greatly advanced thanks to the use of unmonochromatic synchrotron hard X-rays. The recent advances are going beyond microradiology and microtomography to reach nanometre scale. This paper reviews basic theory and selected applications to biomedical and materials sciences. The forthcoming improvements in phase contrast X-ray imaging will lead to even better

  4. Soft X-rays from IC443

    Microsoft Academic Search

    S. Shulman; S. Naranan; G. Fritz; H. Friedman

    1976-01-01

    Results are reported for a rocket-borne soft X-ray sky survey which scanned the region including the supernova remnant IC 443 and the Crab Nebula using large-area proportional counters. X-ray emission from IC 443 was detected in the energy range from 0.6 to 1.0 keV. Assuming that shock-heated gas is responsible for this X-ray emission, suggestions are made for obtaining agreement

  5. Ultrashort X-ray pulse science

    SciTech Connect

    Chin, A.H. [Univ. of California, Berkeley, CA (US). Dept. of Physics]|[Lawrence Berkeley National Lab., CA (US). Materials Science Div.

    1998-05-01

    A variety of phenomena involves atomic motion on the femtosecond time-scale. These phenomena have been studied using ultrashort optical pulses, which indirectly probe atomic positions through changes in optical properties. Because x-rays can more directly probe atomic positions, ultrashort x-ray pulses are better suited for the study of ultrafast structural dynamics. One approach towards generating ultrashort x-ray pulses is by 90{sup o} Thomson scattering between terawatt laser pulses and relativistic electrons. Using this technique, the author generated {approx} 300 fs, 30 keV (0.4 {angstrom}) x-ray pulses. These x-ray pulses are absolutely synchronized with ultrashort laser pulses, allowing femtosecond optical pump/x-ray probe experiments to be performed. Using the right-angle Thomson scattering x-ray source, the author performed time-resolved x-ray diffraction studies of laser-perturbated InSb. These experiments revealed a delayed onset of lattice expansion. This delay is due to the energy relaxation from a dense electron-hole plasma to the lattice. The dense electron-hole plasma first undergoes Auger recombination, which reduces the carrier concentration while maintaining energy content. Longitudinal-optic (LO) phonon emission then couples energy to the lattice. LO phonon decay into acoustic phonons, and acoustic phonon propagation then causes the growth of a thermally expanded layer. Source characterization is instrumental in utilizing ultrashort x-ray pulses in time-resolved x-ray spectroscopies. By measurement of the electron beam diameter at the generation point, the pulse duration of the Thomson scattered x-rays is determined. Analysis of the Thomson scattered x-ray beam properties also provides a novel means of electron bunch characterization. Although the pulse duration is inferred for the Thomson scattering x-ray source, direct measurement is required for other x-ray pulse sources. A method based on the laser-assisted photoelectric effect (LAPE) has been demonstrated as a means of measuring ultrashort x-ray pulse durations. LAPE may also serve as the basis for a gated x-ray detector.

  6. X-ray laser microscope apparatus

    DOEpatents

    Suckewer, Szymon (Princeton, NJ); DiCicco, Darrell S. (Plainsboro, NJ); Hirschberg, Joseph G. (Coral Gables, FL); Meixler, Lewis D. (East Windsor, NJ); Sathre, Robert (Princeton, NJ); Skinner, Charles H. (Lawrenceville, NJ)

    1990-01-01

    A microscope consisting of an x-ray contact microscope and an optical microscope. The optical, phase contrast, microscope is used to align a target with respect to a source of soft x-rays. The source of soft x-rays preferably comprises an x-ray laser but could comprise a synchrotron or other pulse source of x-rays. Transparent resist material is used to support the target. The optical microscope is located on the opposite side of the transparent resist material from the target and is employed to align the target with respect to the anticipated soft x-ray laser beam. After alignment with the use of the optical microscope, the target is exposed to the soft x-ray laser beam. The x-ray sensitive transparent resist material whose chemical bonds are altered by the x-ray beam passing through the target mater GOVERNMENT LICENSE RIGHTS This invention was made with government support under Contract No. De-FG02-86ER13609 awarded by the Department of Energy. The Government has certain rights in this invention.

  7. Compound refractive X-ray lens

    DOEpatents

    Nygren, David R. (Berkeley, CA); Cahn, Robert (Walnut Creek, CA); Cederstrom, Bjorn (Traellborg, SE); Danielsson, Mats (Stocksund, SE); Vestlund, Jonas (Stockholm, SE)

    2000-01-01

    An apparatus and method for focusing X-rays. In one embodiment, his invention is a commercial-grade compound refractive X-ray lens. The commercial-grade compound refractive X-ray lens includes a volume of low-Z material. The volume of low-Z material has a first surface which is adapted to receive X-rays of commercially-applicable power emitted from a commercial-grade X-ray source. The volume of low-Z material also has a second surface from which emerge the X-rays of commercially-applicable power which were received at the first surface. Additionally, the commercial-grade compound refractive X-ray lens includes a plurality of openings which are disposed between the first surface and the second surface. The plurality of openings are oriented such that the X-rays of commercially-applicable power which are received at the first surface, pass through the volume of low-Z material and through the plurality openings. In so doing, the X-rays which emerge from the second surface are refracted to a focal point.

  8. Models for galactic x-ray sources

    SciTech Connect

    Joss, P.C.

    1980-01-01

    Attention is given to those compact galactic x-ray sources whose x-ray luminosities are considerably in excess of the solar luminosity. It is pointed out that the key breakthrough in the development of an understanding of compact galactic x-ray sources was the discovery of x-ray pulsars with the UHURU satellite. There is now overwhelming evidence that these objects are neutron stars in close binary stellar systems. The x-ray pulsations are thought to be thermal emission from the magnetic polar caps of a neutron star that is accreting matter from a companion star and whose magnetic field is misaligned with its rotation axis. Among the compact galactic x-ray sources that are not x-ray pulsars, some still show direct evidence of binary membership, such as x-ray eclipses. There is evidence that the galactic-bulge sources are, in fact, close binary stellar systems. It is concluded, that the great majority of bright galactic x-ray sources, with only a tiny handful of exceptions (such as the Crab and Vela pulsars), are likely to be binaries.

  9. Models for galactic X-ray sources

    NASA Technical Reports Server (NTRS)

    Joss, P. C.

    1980-01-01

    Attention is given to those compact galactic X-ray sources whose X-ray luminosities are considerably in excess of the solar luminosity. It is pointed out that the key breakthrough in the development of an understanding of compact galactic X-ray sources was the discovery of X-ray pulsars with the UHURU satellite. There is now overwhelming evidence that these objects are neutron stars in close binary stellar systems. The X-ray pulsations are thought to be thermal emission from the magnetic polar caps of a neutron star that is accreting matter from a companion star and whose magnetic field is misaligned with its rotation axis. Among the compact galactic X-ray sources that are not X-ray pulsars, some still show direct evidence of binary membership, such as X-ray eclipses. There is evidence that the galactic-bulge sources are, in fact, close binary stellar systems. It is concluded, that the great majority of bright galactic X-ray sources, with only a tiny handful of exceptions (such as the Crab and Vela pulsars), are likely to be binaries.

  10. Compact survey of X-ray astronomy

    SciTech Connect

    Gursky, H.

    1983-01-01

    The development of X-ray astronomy began in 1962. At that time the sun was known to be a strong and variable X-ray source and the general features of the radio sky were known. The first significant cosmic X-ray results were obtained from an Aerobee sounding rocket flown on June 12, 1962. The first small satellite dedicated to X-ray astronomy was SAS-1, renamed Uhuru. The results from this satellite firmly established X-ray astronomy as a substantial discipline. A number of strong galactic sources were found to be pulsing in X-rays with short periods. A number of other small satellites, American and European, were launched in the years following the launch of Uhuru. The latest stage of X-ray astronomy began with HEAO-B, renamed The Einstein Observatory after its launch. An X-ray focussing optics was used to produce genuine images of fields in the sky. Attention is given to the characteristics of neutron stars, common stars, clusters of galaxies, the diffuse X-ray background, and future prospects. 14 references.

  11. Frontiers of X-Ray Astronomy

    NASA Astrophysics Data System (ADS)

    Fabian, Andrew C.; Pounds, Kenneth A.; Blandford, Roger D.

    2004-07-01

    Preface; 1. Forty years on from Aerobee 150: a personal perspective K. Pounds; 2. X-ray spectroscopy of astrophysical plasmas S. M. Kahn, E. Behar, A. Kinkhabwala and D. W. Savin; 3. X-rays from stars M. Gudel; 4. X-ray observations of accreting white-dwarf systems M. Cropper, G. Ramsay, C. Hellier, K. Mukai, C. Mauche and D. Pandel; 5. Accretion flows in X-ray binaries C. Done; 6. Recent X-ray observations of supernova remnants C. R. Canizares; 7. Luminous X-ray sources in spiral and star-forming galaxies M. Ward; 8. Cosmological constraints from Chandra observations of galaxy clusters S. W. Allen; 9. Clusters of galaxies: a cosmological probe R. Mushotzky; 10. Obscured active galactic nuclei: the hidden side of the X-ray Universe G. Matt; 11. The Chandra Deep Field-North Survey and the cosmic X-ray background W. N. Brandt, D. M. Alexander, F. E. Bauer and A. E. Hornschemeier; 12. Hunting the first black holes G. Hasinger; 13. X-ray astronomy in the new millennium: a summary R. D. Blandford.

  12. EXOSAT x-ray imaging optics.

    PubMed

    de Korte, P A; Giralt, R; Coste, J N; Ernu, C; Frindel, S; Flamand, J; Contet, J J

    1981-03-15

    The European X-ray Observatory, EXOSAT, to be launched in 1981 will carry two Wolter I x-ray telescopes, each having a geometric area of ~100 cm(2). A qualification model of the Wolter I optics has been manufactured and extensively tested in optical and x-ray beams. The influence of manufacturing tolerances on the resolution of the optics is discussed, and mechanical and optical measurements of those deviations are presented. Finally, the x-ray imaging quality of the optics is presented, and the correlation with the achieved tolerances is shown. PMID:20309262

  13. An Imaging X-Ray Polarimetry Mission

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Bellazini, Ronaldo; Costa, Enrico; Ramsey, Brian; O'Dell, Steve; Elsner, Ronald; Pavlov, George; Matt, Giorgio; Kaspi, Victoria; Tennant, Allyn; Coppi, Paolo; Wu, Kinwah; Siegmund, Oswald

    2008-01-01

    Technical progress both in x-ray optics and in polarization-sensitive x-ray detectors, which our groups have pioneered, enables a scientifically powerful---yet inexpensive---dedicated mission for imaging x-ray polarimetry. Such a mission is sufficiently sensitive to measure x-ray (linear) polarization for a broad range of cosmic sources --particularly those involving neutron stars, stellar black holes, and supermassive black holes (active galactic nuclei). We describe the technical elements, discuss a mission concept, and synopsize the important physical and astrophysical questions such a mission would address.

  14. An Imaging X-Ray Polarimetry Mission

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Bellazini, Ronaldo; Costa, Enrico; Ramsey, Brian; O'Dell, Steve; Tennant, Allyn; Elsner, Ronald; Pavlov, George; Matt, Girogio; Kaspi, Vicky; Coppi, Paolo; Wu, Kinwah; Siegmund, Oswald

    2008-01-01

    Technical progress both in x-ray optics and in polarization-sensitive x-ray detectors, which our groups have pioneered, enables a scientifically powerful - yet inexpensive - dedicated mission for imaging x-ray polarimetry. Such a mission is sufficiently sensitive to measure x-ray (linear) polarization for a broad range of cosmic sources --- particularly those involving neutron stars, stellar black holes, and supermassive black holes (active galactic nuclei). We describe the technical elements, discuss a mission concept, and synopsiz:e the important physical and astrophysical questions such as mission would address.

  15. Imaging with x-ray lasers

    SciTech Connect

    Da Silva, L.B.; Cauble, B.; Frieders, G.; Koch, J.A.; MacGowan, B.J.; Matthews, D.L.; Mrowka, S.; Ress, D.; Trebes, J.E.; Weiland, T.L.

    1993-11-01

    Collisionally pumped soft x-ray lasers now operate over a wavelength range extending from 35--300 {Angstrom}. These sources have high peak brightness and are now being utilized for x-ray imaging and plasma interferometry. In this paper we will describe our efforts to probe long scalelength plasmas using Moire deflectrometry and soft x-ray imaging. The progress in the development of short pulse x-ray lasers using a double pulse irradiation technique which incorporates a travelling wave pump will also be presented.

  16. Microscopic x-ray luminescence computed tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhu, Dianwen; Zhang, Kun; Li, Changqing

    2015-03-01

    X-ray luminescence computed tomography (XLCT) was emerged as a new hybrid imaging modality, in which the x-rays are used to excite phosphors emitting optical photons to be measured for imaging. In this paper, we reported a microscopic x-ray luminescence computed tomography (microXLCT) with a spatial resolution up to hundreds of micrometers for deep targets. We use a superfine x-ray pencil beam to scan the phosphor targets. The superfine x-ray pencil beam is generated by a small collimator mounted in front of a powerful x-ray tube (93212, Oxford Instrument). A CT detector is used to image the x-ray beam. We have generated an x-ray beam with a diameter of 192 micrometers with a collimator of 100 micrometers in diameter. The emitted optical photons on the top surface of phantom are reflected by a mirror and acquired by an electron multiplier charge-coupled device (EMCCD) camera (C9100-13, Hamamatsu Photonics). The microXLCT imaging system is built inside an x-ray shielding and light tight cabinet. The EMCCD camera is placed in a lead box. All the imaging components are controlled by a VC++ program. The optical photon propagation is modeled with the diffusion equation solved by the finite element method. We have applied different regularization methods including L2 and L1 in the microXLCT reconstruction algorithms. Numerical simulations and phantom experiments are used to validate the microXLCT imaging system.

  17. X-rays from the youngest stars

    NASA Astrophysics Data System (ADS)

    Feigelson, Eric D.

    1994-01-01

    The X-ray properties of classical and weak-lined T Tauri stars are briefly reviewed, emphasizing recent results from the ROSAT satellite and prospects for ASCA. The interpretation of the high level of T Tauri X-rays as enhanced solar-type magnetic activity is discussed and criticized. The census of X-ray emitters is significantly increasing estimates of galactic star formation efficiency, and X-ray emission may be important for self-regulation of star formation. ASCA images will detect star formation regions out to several kiloparsecs and will study the magnetically heated plasma around T Tauri stars. However, images will often suffer from crowding effects.

  18. Soft x-ray interferometry

    SciTech Connect

    Not Available

    1993-09-01

    The purpose of the soft x-ray interferometry workshop held at Lawrence Berkeley Laboratory was to discuss with the scientific community the proposed technical design of the soft x-ray Fourier-transform spectrometer being developed at the ALS. Different design strategies for the instrument`s components were discussed, as well as detection methods, signal processing issues, and how to meet the manufacturing tolerances that are necessary for the instrument to achieve the desired levels of performance. Workshop participants were encouraged to report on their experiences in the field of Fourier transform spectroscopy. The ALS is developing a Fourier transform spectrometer that is intended to operate up to 100 eV. The motivation is solely improved resolution and not the throughput (Jaquinot) or multiplex (Fellgett) advantage, neither of which apply for the sources and detectors used in this spectral range. The proposed implementation of this is via a Mach-Zehnder geometry that has been (1) distorted from a square to a rhombus to get grazing incidence of a suitable angle for 100 eV and (2) provided with a mirror-motion system to make the path difference between the interfering beams tunable. The experiment consists of measuring the emergent light intensity (I(x)) as a function of the path difference (x). The resolving power of the system is limited by the amount of path difference obtainable that is 1 cm (one million half-waves at 200{angstrom} wavelength) in the design thus allowing a resolving power of one million. The free spectral range of the system is limited by the closeness with which the function I(x) is sampled. It is proposed to illuminate a helium absorption cell with roughly 1%-band-width light from a monochromator thus allowing one hundred aliases without spectral overlap even for sampling of I(x) at one hundredth of the Nyquist frequency.

  19. X-ray imaging using a tunable coherent X-ray source based on parametric X-ray radiation

    NASA Astrophysics Data System (ADS)

    Hayakawa, Y.; Takahashi, Y.; Kuwada, T.; Sakae, T.; Tanaka, T.; Nakao, K.; Nogami, K.; Inagaki, M.; Hayakawa, K.; Sato, I.

    2013-08-01

    A novel X-ray source based on parametric X-ray radiation (PXR) has been employed for X-ray imaging at the Laboratory for Electron Beam Research and Application (LEBRA), Nihon University. Notable features of PXR are tunable energy, monochromaticity with spatial chirp, narrow local bandwidth and spatial coherence. Since the X-ray beam from the PXR system has a large irradiation area with uniform flux density, the PXR-based source is suited for X-ray imaging, especially for application to phase-contrast imaging. Despite the cone-like X-ray beam, diffraction-enhanced imaging (DEI) can be employed as a phase contrast imaging technique. DEI experiments were performed using 14- to 34-keV X-rays and the phase-gradient images were obtained. The results demonstrated the capability of PXR as an X-ray source for phase-contrast imaging with a large irradiation field attributed to the cone-beam effect. Given the significant properties of the LEBRA-PXR source, the result suggests the possible construction of a compact linac-driven PXR-Imaging instrument and its application to medical diagnoses.

  20. The Discovery of Soft X-ray Loud Broad Absorption Line Quasars

    E-print Network

    Ghosh, Kajal K

    2008-01-01

    It is been known for more than a decade that BALQSOs (broad absorption line quasars) are highly attenuated in the X-ray regime compared to other quasars, especially in the soft band ($loud" BALQSOs that, by definition, have soft X-ray (0.3 keV) to UV ($3000 \\AA$) flux density ratios that are higher than typical nonBAL radio quiet quasars. Our sample of 3 sources includes one LoBALQSO (low ionization BALQSO) which are generally considered to be the most highly attenuated in the X-rays. The three QSOs are the only known BALQSOs that have X-ray observations that are consistent with no intrinsic soft X-ray absorption. The existence of a large X-ray luminosity and the hard ionizing continuum that it presents to potential UV absorption gas is in conflict with the ionization states that are conducive to line driving forces within BAL winds (especially for the LoBALs).

  1. Dual-Energy X-Ray CT by Compton Scattering Hard X-Ray Source

    Microsoft Academic Search

    T. Kaneyasu; M. Uesaka; K. Dobashi; M. Torikoshi

    2005-01-01

    We are developing a compact Compton scattering hard X-ray source by the X-band linac and YAG lasers at Nuclear Professional School, University of Tokyo. The compact hard X-ray source can produce tunable monochromatic hard X-rays for 10 - 40 keV. The monochromatic hard X-rays are very useful in large fields of medical and biological sciences. We are planning to carry

  2. Wavelength Dispersive X-ray Absorption Fine Structure Imaging by Parametric X-ray Radiation

    Microsoft Academic Search

    Manabu Inagaki; Yasushi Hayakawa; Kyoko Nogami; Toshinari Tanaka; Ken Hayakawa; Takeshi Sakai; Keisuke Nakao; Isamu Sato

    2008-01-01

    The parametric X-ray radiation (PXR) generator system at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University is a monochromatic and coherent X-ray source with horizontal wavelength dispersion. The energy definition of the X-rays, which depends on the horizontal size of the incident electron beam on the generator target crystal, has been investigated experimentally by measuring the X-ray

  3. Biomedical Applications of X-ray Microscopy and X-ray Absorption Spectroscopy

    Microsoft Academic Search

    Peter A. Lay; Carolyn T. Dillon; Hugh H. Harris; Jade B. Aitken; Aviva Levina; Irma Mulyani; Barry Lai; Zhonghou Cai; Stefan Vogt; Paul K. Witting; Shane Thomas; Roland Stocker; Harold Eastgate; Concord NSW

    2006-01-01

    Hard X-ray microprobe techniques: synchrotron-induced X-ray emission (SRIXE) for elemental mapping at a sub-micron level; and micro-XANES (X-ray absorption near-edge structure); are providing unprecedented information on biotransformations of drugs, toxins and carcinogens, as well as normal biological processes and disease conditions at the molecular and cellular levels. These microscopy-based techniques have been combined with X-ray absorption spectroscopy (XAS) on isolated

  4. High time resolution X-ray streak camera with X-ray microscope

    Microsoft Academic Search

    N. Fleurot; J. P. Gex; M. Lamy; C. Quinnesiere; R. Sauneuf

    1977-01-01

    The paper reports characteristics and applications of high resolution X-ray streak cameras used to study plasmas. The camera structure is examined, and a device for converting X-rays into photocathode tube images is described. The ability of each of two X-ray microscopes with cylindrical mirrors to improve streak camera data quality was tested, and resolution properties are indicated. X-ray images and

  5. Design of a stereoscopic X-ray imaging system using a single X-ray source

    Microsoft Academic Search

    J. P. O Evans; M Robinson

    2000-01-01

    The design of a prototype binocular stereoscopic X-ray imaging system for a security screening application is presented. This is based on an innovative technique [Evans JPO, Robinson M, Godber SX. A new stereoscopic imaging technique using a single X-ray source: theoretical analysis. NDT&E International 1996;29(1):27–35] utilising a single X-ray source and a pair of linear X-ray detector arrays. The image

  6. Soft X-ray -- Induced Shock Loading of Meteorite and Planetary Materials

    NASA Astrophysics Data System (ADS)

    Remo, John; Furnish, Michael

    2007-06-01

    The response of meteorite and planetary materials to high- intensity <1 keV x-rays from Z-pinch sources is described. These materials include iron and stony meteorites, magnesium rich olivine (dunite), and Al and Fe calibration samples. Input stresses varied from 6.1 to 12.4 GPa, attenuating to ˜ 1.4 to 2.5 GPa for the iron meteorites, ˜ 0.3 to 1.9 GPa for the stony meteorites, and 1.64 to 1.91 GPa for dunite. The calibration (pure) metals showed less attenuation than the highly inhomogeneous natural materials: 9.5 to ˜ 5 GPa for Fe and 12.4 to 10.6 GP for Al. Putative equations of state are computed from Hugoniot pressure and shock velocity as a function of particle velocity. These data are useful for planetary and astrophysical modeling and for near-Earth object mitigation studies requiring momentum coupling, and momentum enhancement coefficients. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  7. X-ray scattering in X-ray fluorescence spectra with X-ray tube excitation – Modelling, experiment, and Monte-Carlo simulation

    Microsoft Academic Search

    V.-D. Hodoroaba; M. Radtke; L. Vincze; V. Rackwitz; D. Reuter

    2010-01-01

    X-ray scattering may contribute significantly to the spectral background of X-ray fluorescence (XRF) spectra. Based on metrological measurements carried out with a scanning electron microscope (SEM) having attached a well characterised X-ray source (polychromatic X-ray tube) and a calibrated energy dispersive X-ray spectrometer (EDS) the accuracy of a physical model for X-ray scattering is systematically evaluated for representative samples. The

  8. Glancing angle x-ray fluorescence and its application in x-ray technique

    NASA Astrophysics Data System (ADS)

    Dudchik, Yury I.; Komarov, Fadei F.; Konstantinov, Yaroslav A.

    1996-07-01

    Calculation procedures and experimental results form glancing angle x-ray fluorescence from thin films on a flat substrate are presented. A new x-ray tube unit with a super smooth-surface anode and a built-in waveguide collimator is described. The unit makes it possible to obtain narrowly- collimated beams of x-ray radiation with a microfocus line.

  9. Multimodal hard X-ray imaging of a mammography phantom at a compact synchrotron light source

    PubMed Central

    Schleede, Simone; Bech, Martin; Achterhold, Klaus; Potdevin, Guillaume; Gifford, Martin; Loewen, Rod; Limborg, Cecile; Ruth, Ronald; Pfeiffer, Franz

    2012-01-01

    The Compact Light Source is a miniature synchrotron producing X-rays at the interaction point of a counter-propagating laser pulse and electron bunch through the process of inverse Compton scattering. The small transverse size of the luminous region yields a highly coherent beam with an angular divergence of a few milliradians. The intrinsic monochromaticity and coherence of the produced X-rays can be exploited in high-sensitivity differential phase-contrast imaging with a grating-based interferometer. Here, the first multimodal X-ray imaging experiments at the Compact Light Source at a clinically compatible X-ray energy of 21?keV are reported. Dose-compatible measurements of a mammography phantom clearly demonstrate an increase in contrast attainable through differential phase and dark-field imaging over conventional attenuation-based projections. PMID:22713884

  10. Diffraction-Enhanced Imaging of Musculoskeletal Tissues Using a Conventional X-Ray Tube

    SciTech Connect

    Muehleman, C.; Li, J; Connor, D; Parham, C; Pisano, E; Zhong, Z

    2009-01-01

    DEI based on a conventional x-ray tube allows the visualization of skeletal and soft tissues simultaneously. Although more in-depth testing and optimization of the DEI setup must be carried out, these data demonstrate a proof of principle for further development of the technology for future clinical imaging. In conventional projection radiography, cartilage and other soft tissues do not produce enough radiographic contrast to be distinguishable from each other. Diffraction-enhanced imaging (DEI) uses a monochromatic x-ray beam and a silicon crystal analyzer to produce images in which attenuation contrast is greatly enhanced and x-ray refraction at tissue boundaries can be detected. The aim of this study was to test the efficacy of conventional x-ray tube-based DEI for the detection of soft tissues in experimental samples.

  11. Borman effect in resonant diffraction of X-rays

    SciTech Connect

    Oreshko, A. P., E-mail: ap.oreshko@physics.msu.ru [Moscow State University (Russian Federation)

    2013-08-15

    A dynamic theory of resonant diffraction (occurring when the energy of incident radiation is close to the energy of the absorption edge of an element in the composition of a given substance) of synchronous X-rays is developed in the two-wave approximation in the coplanar Laue geometry for large grazing angles in perfect crystals. A sharp decrease in the absorption coefficient in the substance with simultaneously satisfied diffraction conditions (Borman effect) is demonstrated, and the theoretical and first experimental results are compared. The calculations reveal the possibility of applying this approach in analyzing the quadrupole-quadrupole contribution to the absorption coefficient.

  12. The Zoo of X-ray Pulsars

    E-print Network

    S. Mereghetti

    2001-02-01

    I review some recent developments in the field of X-ray pulsars: the discovery of millisecond pulsations in the Low Mass Binary System SAX J1808.4-3658, the large number of transient Be systems discovered in the Magellanic Clouds and the enigmatic class of objects known as Anomalous X-ray Pulsars.

  13. X-Ray Detection Visits the Classroom

    ERIC Educational Resources Information Center

    Peralta, Luis; Farinha, Ana; Pinto, Ana

    2008-01-01

    Film has been used to detect x-rays since the early days of their discovery by Rontgen. Although nowadays superseded by other techniques, film still provides a cheap means of x-ray detection, making it attractive in high-school or undergraduate university courses. If some sort of quantitative result is required, the film's optical absorbance or…

  14. X-ray objective grating spectrograph

    NASA Technical Reports Server (NTRS)

    Catura, R. C.; Stern, R. A.; Cash, W.; Windt, D. L.; Culhane, J. L.

    1988-01-01

    A grazing incidence X-ray spectrograph for investigating the spectra of cosmic X-ray sources is described. The overall instrument design is reviewed, and the key components of the spectrograph, including the gratings, telescope, and detector, are examined. Preliminary performance measurements are reported and plans for the instrument are addressed.

  15. X-ray free-electron lasers

    Microsoft Academic Search

    Neil R. Thompson; Brian W. J. McNeil

    2010-01-01

    With intensities 108–1010 times greater than other laboratory sources, X-ray free-electron lasers are currently opening up new frontiers across many areas of science. In this Review we describe how these unconventional lasers work, discuss the range of new sources being developed worldwide, and consider how such X-ray sources may develop over the coming years.

  16. Instrumental technique in X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Peterson, L. E.

    1975-01-01

    A detailed review of the development of instruments for X-ray astronomy is given with major emphasis on nonfocusing high-sensitivity counter techniques used to detect cosmic photons in the energy range between 0.20 and 300 keV. The present status of X-ray astronomy is summarized together with significant results of the Uhuru observations, and photon interactions of importance for the detection of X-rays in space are noted. The three principal devices used in X-ray astronomy (proportional, scintillation, and solid-state counters) are described in detail, data-processing systems for these devices are briefly discussed, and the statistics of nuclear counting as applied to X-ray astronomy is outlined analytically. Effects of the near-earth X-ray environment and atmospheric gamma-ray production on X-ray detection by low-orbit satellites are considered. Several contemporary instruments are described (proportional-counter systems, scintillation-counter telescopes, modulation collimators), and X-ray astronomical satellite missions are tabulated.

  17. Subpicosecond Coherent Manipulation of X-Rays

    SciTech Connect

    Adams, Bernhard W. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave., Argonne, IL 60439 (United States)

    2004-05-12

    The Takagi-Taupin theory is synthesized with the eikonal theory in a unified space-time approach, based upon microscopic electromagnetism. It is designed specifically to address x-ray diffraction in crystal structures being modified within down to a few femtosconds. Possible applications in the subpicosecond coherent manipulation of x-rays are given.

  18. X-ray Absorption Fine Structure Techniques

    Microsoft Academic Search

    Zhongrui Li; Enkeleda Dervishi; Viney Saini; Liqiu Zheng; Wensheng Yan; Shiqiang Wei; Yang Xu; Alexandru S. Biris

    2010-01-01

    X-ray absorption fine structure spectroscopy (XAFS) is a unique probe for local atomic and electronic structure of absorbing centers in particulate science, physics, chemistry, and biology. During the past several decades, XAFS has gained dramatic advances in every aspect, including theoretical explanation and experimental applications. In this review, we outline the basic physics underlying the X-ray absorption process, experimental design,

  19. MSGC tests with X-rays

    SciTech Connect

    Boulogne, Isabelle [F.R.I.A Grant, University of Mons-Hainaut, B-7000 (Belgium); Daubie, Evelyne [University of Mons-Hainaut, B-7000 Mons (Belgium)

    1998-02-01

    Tests of MSGC detectors using an X-ray generator are reported. Results are presented for gas mixtures composed of Ar or Ne and dimethylether. The influence of the drift field and of the X-ray beam intensity is investigated.

  20. X-ray Analysis of Unknown Minerals

    NSDL National Science Digital Library

    Dexter Perkins

    In this exercise, students use X-ray analysis to identify unknown minerals. They are given two samples to grind up and X-ray, using Jade to identify them. Once the minerals are identified, students make a spreadsheet and do a series of calculations.

  1. X-Ray Exam: Scoliosis (For Parents)

    MedlinePLUS

    What It Is A scoliosis X-ray is a relatively safe and painless test that uses a small amount of radiation to create detailed images of the spine. During the examination, an X-ray machine sends a beam of radiation through ...

  2. X-raying clumped stellar winds

    E-print Network

    Oskinova, L M; Feldmeier, A

    2008-01-01

    X-ray spectroscopy is a sensitive probe of stellar winds. X-rays originate from optically thin shock-heated plasma deep inside the wind and propagate outwards throughout absorbing cool material. Recent analyses of the line ratios from He-like ions in the X-ray spectra of O-stars highlighted problems with this general paradigm: the measured line ratios of highest ions are consistent with the location of the hottest X-ray emitting plasma very close to the base of the wind, perhaps indicating the presence of a corona, while measurements from lower ions conform with the wind-embedded shock model. Generally, to correctly model the emerging X-ray spectra, a detailed knowledge of the cool wind opacities based on stellar atmosphere models is prerequisite. A nearly grey stellar wind opacity for the X-rays is deduced from the analyses of high-resolution X-ray spectra. This indicates that the stellar winds are strongly clumped. Furthermore, the nearly symmetric shape of X-ray emission line profiles can be explained if t...

  3. High resolution X-ray scattering measurements

    NASA Technical Reports Server (NTRS)

    Zombeck, M. V.; Braeuninger, H.; Ondrusch, A.; Predehl, P.

    1982-01-01

    The results of high angular resolution grazing incidence scattering measurements of highly polished, coated optical flats in the X-ray spectral range of 1.5 to 6.4 keV are reported. The interpretation of these results in terms of surface microtopography is presented and the implications for grazing incidence X-ray imaging are discussed.

  4. Chandra X-ray Observatory Center

    E-print Network

    Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St arcmin (About 52,000 x 87,000 light years) Chandra X-ray Observatory ACIS Image CXC operated for NASA by the Smithsonian Astrophysical Observatory #12;

  5. Chandra X-ray Observatory Center

    E-print Network

    Chandra X-ray Observatory Center Harvard-Smithsonian Center for Astrophysics 60 Garden St the density is large enough. Scale: Image is 37 arcmin across (about 15 light years) Chandra X-ray Observatory ACIS Image CXC operated for NASA by the Smithsonian Astrophysical Observatory #12;

  6. MICROQUASARS AND X-RAY NOVAE

    E-print Network

    Greiner, Jochen

    Sgr, Cyg X-3, 1E 1740.7 2942, GRS 1915+105 1. Introduction X-ray novae are binary systems-ray binary stars with continuous X-ray activity and production of radio jets. We can think of them in the Galaxy is their astonishing scaled down similarity with extragalactic quasars and active galactic nuclei

  7. X-Ray Imaging Study

    NASA Technical Reports Server (NTRS)

    OBrien, Susan K.; Workman, Gary L.

    1996-01-01

    The space environment in which the Space Station Freedom and other space platforms will orbit is truly a hostile environment. For example, the currently estimated integral fluence for electrons above 1 Mev at 2000 nautical miles is above 2 x 1O(exp 10) electrons/sq cm/day and the proton integral fluence is above 1 x 10(exp 9) protons/sq cm/day. At the 200 - 400 nautical miles, which is more representative of the altitude which will provide the environment for the Space Station, each of these fluences will be proportionally less; however, the data indicates that the radiation environment will obviously have an effect on structural materials exposed to the environment for long durations. The effects of this combined environment is the issue which needs to be understood for the long term exposure of structures in space. At the same time, there will be substantial potential for collisions between the space platforms and space debris. The current NASA catalogue contains over 4500 objects floating in space which are not considered payloads. This debris can have significant effects on collision with orbiting spacecraft. In order to better understand the effect of these hostile phenomena on spacecraft, several types of studies are being performed to simulate at some level the effect of the environment. In particular the study of debris clouds produced by hypervelocity impact on the various surfaces anticipated on the Space Station is very important at this point in time. The need to assess the threat of such debris clouds on space structures is an on-going activity. The Space Debris Impact facility in Building 4612 provides a test facility to monitor the types of damage produced with hypervelocity impact. These facilities are used to simulate space environmental effects from energetic particles. Flash radiography or x-ray imaging has traditionally provided such information and as such has been an important tool for recording damage in situ with the event. The proper operation of the system can provide much useful information with respect to parametric analysis of the hypervelocity experiment. The following report outlines the procedures developed to optimize the operation of the x-ray imaging system and its operational characteristics.

  8. X-rays from Planetary Nebulae

    E-print Network

    You-Hua Chu; Martin A. Guerrero; Robert A. Gruendl

    1999-09-06

    Two sources of X-ray emission are expected from planetary nebulae: the hot central stars with $T_{eff} > 10^5$ K, and shocked fast stellar winds at temperatures of 10$^6 - 10^7$ K. The stellar emission and nebular emission differ in spatial distribution and spectral properties. Observations of X-ray emission from PNe may provide essential information on formation mechanisms and physical conditions of PNe. X-ray emission from PNe has been detected by Einstein and EXOSAT, but significant advances are made only after ROSAT became available. The ROSAT archive contains useful observations of ~80 PNe, of which 13 are detected. Three types of X-ray spectra are seen. Only three PNe are marginally resolved by the ROSAT instruments. In the near future, Chandra will provide X-ray observations with much higher angular and spectral resolution, and help us understand the central stars as well as the hot interiors of PNe.

  9. Modelling X-ray reverberation lags

    NASA Astrophysics Data System (ADS)

    Cackett, E.

    2015-07-01

    The recent detection of X-ray reverberation lags, especially in the Fe K? line region, around Active Galactic Nuclei (AGN) has opened up the possibility of studying the time-resolved response (reflection) of hard X-rays from the accretion disk around supermassive black holes. More recently, there has been a hint of Fe K? reverberation seen in a neutron star low-mass X-ray binary (LMXB) also. Here, we use general relativistic transfer functions for reflection of X-rays from a point source located at some height above the compact object to study the time lags expected as a function of frequency and energy in the Fe K? line region. We explore the models and the dependence of the lags on key parameters such as the height of the X-ray source, accretion disk inclination, spin and mass. We apply these models to reverberation lags in AGN and neutron star LMXBs.

  10. Modeling Broadband X-Ray Absorption of Massive Star Winds

    NASA Technical Reports Server (NTRS)

    Leutenegger, Maurice A.; Cohen,David H.; Zsargo, Janos; Martell, Erin M.; MacArthur, James P.; Owocki, Stanley P.; Gagne, Marc; Hillier, D. John

    2010-01-01

    We present a method for computing the net transition of X-rays emitted by shock-heated plasma distributed throughout a partially optically thick stellar wind from a massive star. We find the transmission by an exact integration of the formal solution, assuming the emitting plasma and absorbing plasma are mixed at a constant mass ratio above some minimum radius, below which there is assumed to be no emission. This model is more realistic than either the slab absorption associated with a corona at the base of the wind or the exospheric approximation that assumes all observed X-rays are emitted without attenuation from above the radius of optical depth unity. Our model is implemented in XSPEC as a pre-calculated table that can be coupled to a user-defined table of the wavelength dependent wind opacity. We provide a default wind opacity model that is more representative of real wind opacities than the commonly used neutral ISM tabulation. Preliminary modeling of Chandra grating data indicates that the X-ray hardness trend of OB stars with spectral subtype cars largely be understood as a wind absorption effect.

  11. Quantitative imaging using high-energy X-ray phase-contrast CT with a 70 kVp polychromatic X-ray spectrum.

    PubMed

    Sarapata, Adrian; Willner, Marian; Walter, Marco; Duttenhofer, Thomas; Kaiser, Konradin; Meyer, Pascal; Braun, Christian; Fingerle, Alexander; Noël, Peter B; Pfeiffer, Franz; Herzen, Julia

    2015-01-12

    Imaging of large and dense objects with grating-based X-ray phase-contrast computed tomography requires high X-ray photon energy and large fields of view. It has become increasingly possible due to the improvements in the grating manufacturing processes. Using a high-energy X-ray phase-contrast CT setup with a large (10 cm in diameter) analyzer grating and operated at an acceleration tube voltage of 70 kVp, we investigate the complementarity of both attenuation and phase contrast modalities with materials of various atomic numbers (Z). We confirm experimentally that for low-Z materials, phase contrast yields no additional information content over attenuation images, yet it provides increased contrast-to-noise ratios (CNRs). The complementarity of both signals can be seen again with increasing Z of the materials and a more comprehensive material characterization is thus possible. Imaging of a part of a human cervical spine with intervertebral discs surrounded by bones and various soft tissue types showcases the benefit of high-energy X-ray phase-contrast system. Phase-contrast reconstruction reveals the internal structure of the discs and makes the boundary between the disc annulus and nucleus pulposus visible. Despite the fact that it still remains challenging to develop a high-energy grating interferometer with a broad polychromatic source with satisfactory optical performance, improved image quality for phase contrast as compared to attenuation contrast can be obtained and new exciting applications foreseen. PMID:25835698

  12. X-ray studies of near-frictionless carbon films.

    SciTech Connect

    Mehta, N. J.; Roy, S.; Johnson, J. A.; Woodford, J.; Zinovev, A.; Islam, Z.; Erdemir, A.; Sinha, S.; Fenske, G.; Prorok, B.; Energy Technology; Univ. of California; Auburn Univ.

    2005-01-01

    Carbon-based coatings exhibit many attractive properties that make them good candidates for a wide range of engineering applications. Tribological studies of the films have revealed a close correlation between the chemistry of the hydrocarbon source gases and the coefficients of friction and wear rates of the diamond-like carbon films. Those films grown in source gases with higher hydrogen-to-carbon ratios had much lower coefficients of friction and wear rates than did films derived from source gases with lower hydrogen-to-carbon ratios. The mechanism for this low friction is as yet not properly understood. Ongoing structural characterization of the films at Argonne National Laboratory is gradually revealing this mechanism. Recent studies have included x-ray photoelectron spectroscopy (XPS), near edge x-ray absorption fine structure (NEXAFS) and x-ray reflectivity (XRR). XPS showed {approx}10% oxygen at the surface, which was largely removed after a 1 minute sputter; NEXAFS showed a high sp2:sp3 ratio implying a highly graphitic material; and XRR has given a comprehensive depth profile, with three layers of increasing density as the substrate was approached. The paper discusses the results and correlation with previous friction measurements.

  13. Detection of x ray sources in PROS

    NASA Technical Reports Server (NTRS)

    Deponte, J.; Primini, F. A.

    1992-01-01

    The problem of detecting discrete sources in x-ray images has much in common with the problem of automatic source detection at other wavelengths. In all cases, one searches for positive brightness enhancements exceeding a certain threshold, which appear consistent with what one expects for a point source, in the presence of a (possibly) spatially variable background. Multidimensional point spread functions (e.g., dependent on detector position and photon energy) are also common. At the same time, the problem in x-ray astronomy has some unique aspects. For example, for typical x-ray exposures in current or recent observatories, the number of available pixels far exceeds the number of actual x-ray events, so Poisson, rather than Gaussian statistics apply. Further, extended cosmic x-ray sources are common, and one often desires to detect point sources in the vicinity or even within bright, diffuse x-ray emission. Finally, support structures in x-ray detectors often cast sharp shadows in x-ray images making it necessary to detect sources in a region of rapidly varying exposure. We have developed a source detection package within the IRAF/PROS environment which attempts to deal with some of the problems of x-ray source detection. We have patterned our package after the successful Einstein Observatory x-ray source detection programs. However, we have attempted to improve the flexibility and accessibility of the functions and to provide a graphical front-end for the user. Our philosophy has been to use standard IRAF tasks whenever possible for image manipulation and to separate general functions from mission-specific ones. We will report on the current status of the package and discuss future developments, including simulation tasks, to allow the user to assess detection efficiency and source significance, tasks to determine source intensity, and alternative detection algorithms.

  14. Globular Cluster X-ray Sources

    NASA Astrophysics Data System (ADS)

    Pooley, David

    2009-09-01

    Globular clusters and X-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed a population of highly luminous (> 10^{36} erg/s) X-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low luminosity (< 10^{33} erg/s) X-ray sources. It was realized early on that the high luminosity sources were low-mass X-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the Galaxy. However, the low luminosity sources proved difficult to classify. Many ideas were put forth -- including low-mass X-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs) -- but secure identifications were scarce. In ROSAT observations of 55 globular clusters, about 25 low-luminosity X-ray sources were found. To date, Chandra has observed over 80 Galactic globular clusters, mainly with ACIS, and these observations have revealed over 1500 X-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogenous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of X-ray sources in a globular cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the X-ray sources and shows them to be excellent tracers of the complicated internal dynamics of globular clusters. The relation between the encounter frequency and the number of X-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters.

  15. Quantitative Measurements of X-ray Intensity

    SciTech Connect

    Haugh, M. J., Schneider, M.

    2011-09-01

    This chapter describes the characterization of several X-ray sources and their use in calibrating different types of X-ray cameras at National Security Technologies, LLC (NSTec). The cameras are employed in experimental plasma studies at Lawrence Livermore National Laboratory (LLNL), including the National Ignition Facility (NIF). The sources provide X-rays in the energy range from several hundred eV to 110 keV. The key to this effort is measuring the X-ray beam intensity accurately and traceable to international standards. This is accomplished using photodiodes of several types that are calibrated using radioactive sources and a synchrotron source using methods and materials that are traceable to the U.S. National Institute of Standards and Technology (NIST). The accreditation procedures are described. The chapter begins with an introduction to the fundamental concepts of X-ray physics. The types of X-ray sources that are used for device calibration are described. The next section describes the photodiode types that are used for measuring X-ray intensity: power measuring photodiodes, energy dispersive photodiodes, and cameras comprising photodiodes as pixel elements. Following their description, the methods used to calibrate the primary detectors, the power measuring photodiodes and the energy dispersive photodiodes, as well as the method used to get traceability to international standards are described. The X-ray source beams can then be measured using the primary detectors. The final section then describes the use of the calibrated X-ray beams to calibrate X-ray cameras. Many of the references are web sites that provide databases, explanations of the data and how it was generated, and data calculations for specific cases. Several general reference books related to the major topics are included. Papers expanding some subjects are cited.

  16. Large area soft x-ray collimator to facilitate x-ray optics testing

    NASA Astrophysics Data System (ADS)

    Espy, Samuel L.

    1994-09-01

    The first objective of this program is to design a nested conical foil x-ray optic which will collimate x-rays diverging from a point source. The collimator could then be employed in a small, inexpensive x-ray test stand which would be used to test various x-ray optics and detector systems. The second objective is to demonstrate the fabrication of the x-ray reflectors for this optic using lacquer-smoothing and zero-stress electroforming techniques.

  17. X-rays from Quiescent Low-Mass X-ray Binary Transients

    E-print Network

    Jean-Pierre Lasota

    2000-06-16

    I argue that it is very unlikely that X-rays from quiescent black-hole low-mass X-ray binary transients are emitted by coronae of companion stars. I show that in a simple model in which these X-rays are emitted by an ADAF filling the inner part of an unsteady, dwarf-nova type disc, the X-ray luminosity is correlated with the orbital period. I predict what values of X-ray luminosities from black-hole transient systems should be observed by Chandra and XMM-Newton.

  18. Hard X ray imaging telescope

    NASA Astrophysics Data System (ADS)

    Lubin, P.

    1990-03-01

    This final report covers the work carried out under the LLNL Contract Number B063682, Subcontractor Regents University of California at Santa Barbara. The research carried out under this contract involves the construction of a telemetry, target acquisition and guidance system, and of a light-weight gondola to house an x ray spectrometer. This work is part of the design and construction of the balloon experiment, GRATIS, which will perform the first arcminute imaging of cosmic sources in the 30 to 200 keV energy band. Observations conducted with GRATIS are expected to provide data relevant to several key problems in high energy astrophysics including the physical processes responsible for the high energy tail observed in the soft gamma-ray spectra of clusters of galaxies and the origin of both the diffuse and point source components of the gamma-ray emission from the Galactic Center. This report discusses the scientific motivations for this experiment, presents several aspects of the design and construction of the hardware components, gives an overview of the stabilized platform, and demonstrates the expected performance and sensitivity.

  19. X-ray satellite (Rosat)

    NASA Technical Reports Server (NTRS)

    1986-01-01

    An overview of the current status of the ROSAT X-Ray satellite project is given. Areas discussed include an overview of problem areas, systems and mechanical subsystems, the electrical subsystem, power supply, data processing and transmission, the wide field camera, ground support equipment and the production scheduling. It is shown that the project is proceeding according to schedule, including the hardware production and costs. However, it is stated that estimated additional costs will exceed the plan. The previous schedule for production of the flight model will no longer be met. A modified milestone plan has been worked out with Dornier Systems. The current working schedule calls for a launch data of December 21, 1987; however, this does not take into account a 4-week buffer prior to transporting the flight model to the launch site. As of the date of this report, milestone M5 has been met. Previous problems with the gold vapor deposition on the flight model mirror due to contamination have been eliminated.

  20. Nonthermal X-ray Microflares

    NASA Astrophysics Data System (ADS)

    Christe, S.; Rauscher, E.; Krucker, S.; Lin, R. P.

    2004-12-01

    The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) provides unique sensitivity in the 3-15 keV energy range, with an effective area ˜100 times larger than similar past instruments. Along with its high spectral resolution (1 keV) RHESSI is uniquely suited to study small events. Microflares have been observed by Benz & Grigis (2002) and Krucker et al. (2002) to have anomalously steep spectra ( spectral index between -5 and -8) extending down to ˜ 7 keV. Thermal emission is found to dominate below ˜ 7 keV. In many other respects, microflares show properties similar to larger flares. We present single event studies of different types of x-ray microflares. RHESSI observations during quiet times (04-May 10-14; GOES level low B class) reveal a set 5 microflares (>=A Class). These microflares show power law spectra (spectral index of ˜4-8) with little or no thermal emission in the 3- ˜7 keV energy range above the nonthermal part of the spectrum. Other microflares in the same GOES class range, however, have been found which show extremely hard spectra with emission up to 50 keV (power law index ˜2). At lower energies, emission is dominated by a hot thermal component (20 MK). This work was supported by NASA contract NAS5-98033.

  1. Proton-induced x-ray fluorescence CT imaging

    PubMed Central

    Bazalova-Carter, Magdalena; Ahmad, Moiz; Matsuura, Taeko; Takao, Seishin; Matsuo, Yuto; Fahrig, Rebecca; Shirato, Hiroki; Umegaki, Kikuo; Xing, Lei

    2015-01-01

    Purpose: To demonstrate the feasibility of proton-induced x-ray fluorescence CT (pXFCT) imaging of gold in a small animal sized object by means of experiments and Monte Carlo (MC) simulations. Methods: First, proton-induced gold x-ray fluorescence (pXRF) was measured as a function of gold concentration. Vials of 2.2 cm in diameter filled with 0%–5% Au solutions were irradiated with a 220 MeV proton beam and x-ray fluorescence induced by the interaction of protons, and Au was detected with a 3 × 3 mm2 CdTe detector placed at 90° with respect to the incident proton beam at a distance of 45 cm from the vials. Second, a 7-cm diameter water phantom containing three 2.2-diameter vials with 3%–5% Au solutions was imaged with a 7-mm FWHM 220 MeV proton beam in a first generation CT scanning geometry. X-rays scattered perpendicular to the incident proton beam were acquired with the CdTe detector placed at 45 cm from the phantom positioned on a translation/rotation stage. Twenty one translational steps spaced by 3 mm at each of 36 projection angles spaced by 10° were acquired, and pXFCT images of the phantom were reconstructed with filtered back projection. A simplified geometry of the experimental data acquisition setup was modeled with the MC TOPAS code, and simulation results were compared to the experimental data. Results: A linear relationship between gold pXRF and gold concentration was observed in both experimental and MC simulation data (R2 > 0.99). All Au vials were apparent in the experimental and simulated pXFCT images. Specifically, the 3% Au vial was detectable in the experimental [contrast-to-noise ratio (CNR) = 5.8] and simulated (CNR = 11.5) pXFCT image. Due to fluorescence x-ray attenuation in the higher concentration vials, the 4% and 5% Au contrast were underestimated by 10% and 15%, respectively, in both the experimental and simulated pXFCT images. Conclusions: Proton-induced x-ray fluorescence CT imaging of 3%–5% gold solutions in a small animal sized water phantom has been demonstrated for the first time by means of experiments and MC simulations. PMID:25652502

  2. Quantitative measurement of binary liquid distributions using multiple-tracer x-ray fluorescence and radiography.

    PubMed

    Halls, Benjamin R; Meyer, Terrence R; Kastengren, Alan L

    2015-01-26

    The complex geometry and large index-of-refraction gradients that occur near the point of impingement of binary liquid jets present a challenging environment for optical interrogation. A simultaneous quadruple-tracer x-ray fluorescence and line-of-sight radiography technique is proposed as a means of distinguishing and quantifying individual liquid component distributions prior to, during, and after jet impact. Two different pairs of fluorescence tracers are seeded into each liquid stream to maximize their attenuation ratio for reabsorption correction and differentiation of the two fluids during mixing. This approach for instantaneous correction of x-ray fluorescence reabsorption is compared with a more time-intensive approach of using stereographic reconstruction of x-ray attenuation along multiple lines of sight. The proposed methodology addresses the need for a quantitative measurement technique capable of interrogating optically complex, near-field liquid distributions in many mixing systems of practical interest involving two or more liquid streams. PMID:25835928

  3. A method for normalization of X-ray absorption spectra

    SciTech Connect

    Weng, T.-C.; Waldo, G.S.; Penner-Hahn, J.E. (Michigan)

    2010-07-20

    Accurate normalization of X-ray absorption data is essential for quantitative analysis of near-edge features. A method, implemented as the program MBACK, to normalize X-ray absorption data to tabulated mass absorption coefficients is described. Comparison of conventional normalization methods with MBACK demonstrates that the new normalization method is not sensitive to the shape of the background function, thus allowing accurate comparison of data collected in transmission mode with data collected using fluorescence ion chambers or solid-state fluorescence detectors. The new method is shown to have better reliability and consistency and smaller errors than conventional normalization methods. The sensitivity of the new normalization method is illustrated by analysis of data collected during an equilibrium titration.

  4. Recent X-ray Variability of Eta Car Approaching The X-ray Eclipse

    NASA Technical Reports Server (NTRS)

    Corcoran, M.; Swank, J. H.; Ishibashi, K.; Gull, T.; Humphreys, R.; Damineli, A.; Walborn, N.; Hillier, D. J.; Davidson, K.; White, S. M.

    2002-01-01

    We discuss recent X-ray spectral variability of the supermassive star Eta Car in the interval since the last X-ray eclipse in 1998. We concentrate on the interval just prior to the next X-ray eclipse which is expected to occur in June 2003. We compare the X-ray behavior during the 2001-2003 cycle with the previous cycle (1996-1998) and note similarities and differences in the temporal X-ray behavior. We also compare a recent X-ray observation of Eta Car obtained with the Chandra high energy transmission grating in October 2002 with an earlier observation from Nov 2002, and interpret these results in terms of the proposed colliding wind binary model for the star. In addition we discuss planned observations for the upcoming X-ray eclipse.

  5. Scintillating ribbon x-ray detector

    SciTech Connect

    Kinchen, B.E. [BK Science and Engineering, Fremont, CA (United States); Rogers, A. [Synergistic Detector Designs, Sunnyvale, CA (United States)

    1995-12-31

    A patent in the early 1970`s by Aerojet Corporation in Sacramento, CA put forth the idea of using an array of scintillating fibers for x-ray detection and imaging. In about 1975, Pratt and Whitney Aircraft in East Hartford, CT designed and manufactured an imaging system based on the patent. The device was 1.75 in thick in the direction of the x-ray beam and about 4 in. by 4 in. square. The device was used with a 8 MeV x-ray source to image and measure internal clearances within operating aircraft, gas turbines engines. There are significant advantages of fiber optic detectors in x-ray detection. However, the advantages are often outweighed by the disadvantages. Two of the advantages of scintillating fiber optic x-ray detectors are: (1) high limiting spatial frequency -- between 20 and 25 lp/mm; and (2) excellent x-ray stopping power -- they can be made thick and retain spatial resolution. In traditional fiber optic detectors the x-rays are oriented parallel to the long axis of the fiber. For the scintillating ribbon x-ray sensor, the x-rays are oriented normal to the fiber long axis. This ribbon sensor technique has a number of advantages over the two current radiographic techniques digital x-radiography and x-ray film: The main advantage the ribbon has is size and shape. It can be as thin as 0.05 in., virtually any width or length, and flexible. Once positioned in a given location, 20 to 100 square inches of the object being inspected can be imaged with a single x-ray beam sweep. It is clear that conventional digital cameras do not lend themselves to placement between walls of aircraft structures or similar items requiring x-ray inspections. A prototype scintillating ribbon x-ray sensor has been fabricated and tested by Synergistic Detector Designs. Images were acquired on corrosion test panels of aluminum fabricated by Iowa State University.

  6. Identification of X-ray Point Sources and Study on the Nature of 62 X-ray Globular Cluster Candidates in M31

    E-print Network

    Zhou Fan; Jun Ma; Xu Zhou; Jiansheng Chen; Zhaoji Jiang; Zhenyu Wu

    2005-07-20

    This paper includes two parts. The first is to present the spectral energy distributions (SEDs) of 49 globular cluster (GC) X-ray sources in the BATC 13 intermediate-band filters from 3800 to 10000 A, and identify 8 unidentified X-ray sources in M31. Using the X-ray data of Einstein observation from 1979 to 1980, ROSAT HRI observation in 1990, Chandra HRC and ACIS-I observations from 1999 to 2001, and the BATC optical survey from 1995 to 1999, we find 49 GC X-ray sources and 8 new unidentified X-ray sources in the BATC M31 field. By analyzing SEDs and FWHMs, 4 of the 8 X-ray sources may be GC candidates. The second is to present some statistical relationships about 62 GC X-ray sources, of which 58 are already known, and 4 are identified in this paper. The distribution of M31 GC X-ray sources' V mags is bimodal, with peaks at m_v = 15.65 and m_v = 17.89, which is different from the distribution of GC candidates. The distribution of B-V color shows that,the GC X-ray sources seem to be associated preferentially with the redder GCs, in agreement with the previous results. Kolmogorov-Smirnov test shows that the maximum value of the absolute difference of B-V distributions of GC X-ray sources and GCs is D_{max}=0.181, and the probability P=0.068 which means we can reject the hypothesis that the two distributions are the same at the 90.0% confidence level. In the end, we study the correlation between X-ray luminosity (0.3-10 keV) and the optical luminosity (in V band) of the GC X-ray sources in M31, and find that there exits a weak relationship with the linear correlation coefficient r = 0.36 at the confidence level of 98.0%.

  7. Simultaneous high speed digital cinematographic and X-ray radiographic imaging of a intense multi-fluid interaction with rapid phase changes

    SciTech Connect

    Hansson, Roberta Concilio; Park, Hyun Sun; Dinh, Truc-Nam [Royal Institute of Technology, Division of Nuclear Power Safety, AlbaNova, Stockholm SE-106 91 (Sweden)

    2009-04-15

    As typical for the study of the vapor explosions, the qualitative and quantitative understanding of the phenomena requires visualization of both material and interface dynamics. A new approach to multi-fluid multiphase visualization is presented with the focus on the development of a synchronized high-speed visualization by digital cinematography and X-ray radiography. The developed system, named SHARP (simultaneous high-speed acquisition of X-ray radiography and photography), and its image processing methodology, directed to an image synchronization procedure and a separate quantification of vapor and molten material dynamics, is presented in this paper. Furthermore, we exploit an intrinsic property of the X-ray radiation, namely the differences in linear mass attenuation coefficients over the beam path through a multi-component system, to characterize the evolution of molten material distribution. Analysis of the data obtained by the SHARP system and image processing procedure developed granted new insights into the physics of the vapor explosion phenomena, as well as, quantitative information of the associated dynamic micro-interactions. (author)

  8. A bimodal energy model for correcting beam hardening artefacts in X-ray tomography

    Microsoft Academic Search

    Elke Van de Casteele; Dirk Van Dyck; Jan Sijbers; Erik Raman

    2003-01-01

    As a consequence of the polychromatic X-ray sources, used in micro-computer tomography (?CT) and in medical CT, the attenuation is no longer a linear function of absorber thickness. If this nonlinear beam hardening effect is not compensated, the reconstructed images will be corrupted by cupping artefacts. Here, a bimodal energy model for the energy spectrum is presented, which may be

  9. Toward Active X-ray Telescopes II

    NASA Technical Reports Server (NTRS)

    O'Dell, Stephen L.; Aldroft, Thomas L.; Atkins, Carolyn; Button, Timothy W.; Cotroneo, Vincenzo; Davis, William N.; Doel, Peter; Feldman, Charlotte H.; Freeman, Mark D.; Gubarev, Mikhail V.; Johnson-Wilke, Raegan L.; Kolodziejczak, Jeffery J.; Lillie, Charles F.; Michette, Alan G.; Ramsey, Brian D.; Reid, Paul B.; Sanmartin, Daniel Rodriguez; Saha, Timo T.; Schwartz, Daniel A.; Trolier-McKinstry, Susan E.; Ulmer, Melville P.; Wilke, Rudeger H. T.; Willingale, Richard; Zhang, William W.

    2012-01-01

    In the half century since the initial discovery of an astronomical (non-solar) x-ray source, the sensitivity for detection of cosmic x-ray sources has improved by ten orders of magnitude. Largely responsible for this dramatic progress has been the refinement of the (grazing-incidence) focusing x-ray telescope. The future of x-ray astronomy relies upon the development of x-ray telescopes with larger aperture areas (greater than 1 m2) and finer angular resolution (less than 1.). Combined with the special requirements of grazing-incidence optics, the mass and envelope constraints of space-borne telescopes render such advances technologically challenging.requiring precision fabrication, alignment, and assembly of large areas (greater than 100 m2) of lightweight (approximately 1 kg m2 areal density) mirrors. Achieving precise and stable alignment and figure control may entail active (in-space adjustable) x-ray optics. This paper discusses relevant programmatic and technological issues and summarizes progress toward active x-ray telescopes.

  10. The X-ray binary, UW CMa

    NASA Technical Reports Server (NTRS)

    Heap, S. R.

    1982-01-01

    The UW CMa is a close, eclipsing binary composed of an O7f primary with a stron wind and a less luminous O-type companion. It was found that UW CMa a variable X-ray source, whose X-ray variations are in phase with its optical light curve. Since both components of the binary system are O stars, accretion by a compact object is ruled out as a mechanism for generating X-rays. The UW CMa represents a new class of X-ray binaries, in which X-rays result from the collision of a wind from one star with the surface or wind of the other star. It is hypothesised that the impact of a wind against a star generates a shock wave about 0.25 stellar radii above the stellar surface, and material behind the shock front, heated to bout 10 million degrees, radiates the X-ray apparent X-ray variability is due to its location between the two stars, where it undergoes eclipses. The high temperature region maintains an ionization cavity in the wind, as detected with IUE. The ionization cavity is the source of depletion of absorbing ions in the wind between the two stars.

  11. Experimental investigation of beam heating in a soft X-ray scanning transmission X-ray microscope

    E-print Network

    Hitchcock, Adam P.

    Experimental investigation of beam heating in a soft X-ray scanning transmission X-ray microscope and an accuracy of Æ1 C has been fabricated for scanning transmission X-ray microscopes (STXM). Here we describe the current generation of soft X-ray (60­2500 eV) scan- ning transmission X-ray microscopes (STXM) to focus

  12. Quasar X-ray spectra revisited

    NASA Technical Reports Server (NTRS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; Mcdowell, J.

    1993-01-01

    A sample of 45 quasars observed by the IPC on the Einstein satellite is used to reexamine the relationship of the soft X-ray energy index with radio properties and the optical Fe II emission. The tendency for radio-loud quasars to have systematically flatter X-ray energy indices than radio-quiet quasars is confirmed with the soft X-ray excess having negligible effect. There is a tendency for the flatness of the X-ray slope to correlate with radio core dominance for radio-loud quasars, suggesting that a component of the X-ray emission is relativistically beamed. For the radio-quiet quasars, the soft X-ray energy indices with a mean of about 1.0 are consistent with the indices found at higher energies, although steeper than those observed for Seyfert 1 galaxies where the reflection model gives a good fit to the data. The correlation of Fe II emission line strength with X-ray energy index is confirmed for radio-quiet quasars using a subset of 18 objects. The radio-loud quasars show no evidence for a correlation. This relation suggests a connection between the ionizing continuum and line emission from the broad emission-line region (BELR) of radio-quiet quasars, but in the opposite sense to that predicted by current photoionization models. The correlations of X-ray slope with radio core dominance and Fe II equivalent width within the radio-loud and radio-quiet subclasses, respectively, imply that the observed wide range of X-ray energy indices is real rather than due to the large measuring uncertainties for individual objects.

  13. Quasar x-ray spectra revisited

    NASA Technical Reports Server (NTRS)

    Shastri, P.; Wilkes, B. J.; Elvis, M.; Mcdowell, J.

    1992-01-01

    A sample of 45 quasars observed by the Imaging Proportional Counter (IPC) on the Einstein satellite is used to re-examine the relationship between the soft (0.2-3.5 keV) X-ray energy index and radio-loudness. We found the following: (1) the tendency for radio-loud quasars to have systematically flatter X-ray slopes than radio-quiet quasars (RQQ's) is confirmed with the soft X-ray excess having negligible effect; (2) there is a tendency for the flatness of the X-ray slope to correlate with radio core-dominance for radio-loud quasars, suggesting that a component of the X-ray emission is relativistically beamed; (3) for the RQQ's the soft X-ray slopes, with a mean of approximately 1.0, are consistent with the slopes found at higher energies (2-10 keV) although steeper than those observed for Seyfert 1 galaxies (also 2-10 keV) where the reflection model gives a good fit to the data; (4) the correlation of FeII emission line strength with X-ray energy index is confirmed for radio-quiet quasars using a subset of 18 quasars. The radio-loud quasars show no evidence for a correlation. This relation suggests a connection between the ionizing continuum and the line emission from the broad emission line region (BELR) of radio-quiet quasars, but in the opposite sense to that predicted by current photoionization models; and (5) the correlations of X-ray slope with radio core dominance and FeII equivalent width within the radio-loud and radio-quiet sub-classes respectively imply that the observed wide range of X-ray spectral slopes is real rather than due to the large measuring uncertainties for individual objects.

  14. Globular cluster x-ray sources

    NASA Astrophysics Data System (ADS)

    Pooley, David

    2010-04-01

    Globular clusters and x-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed highly luminous (> 1036 ergs-1) x-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low-luminosity (< 1033 ergs-1) x-ray sources. It was realized early on that the high-luminosity sources were low-mass x-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the galaxy. However, the low-luminosity sources proved difficult to classify. Many ideas were put forth - low-mass x-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs) - but secure identifications were scarce. In ROSAT observations of 55 clusters, about 25 low-luminosity sources were found. Chandra has now observed over 80 Galactic globular clusters, and these observations have revealed over 1,500 x-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogeneous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of x-ray sources in a cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the x-ray sources and shows them to be excellent tracers of the complicated internal dynamics. The relation between the encounter frequency and the number of x-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters.

  15. Globular cluster x-ray sources.

    PubMed

    Pooley, David

    2010-04-20

    Globular clusters and x-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed highly luminous (> 10(36) ergs(-1)) x-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low-luminosity (< 10(33) ergs(-1)) x-ray sources. It was realized early on that the high-luminosity sources were low-mass x-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the galaxy. However, the low-luminosity sources proved difficult to classify. Many ideas were put forth--low-mass x-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs)--but secure identifications were scarce. In ROSAT observations of 55 clusters, about 25 low-luminosity sources were found. Chandra has now observed over 80 Galactic globular clusters, and these observations have revealed over 1,500 x-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogeneous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of x-ray sources in a cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the x-ray sources and shows them to be excellent tracers of the complicated internal dynamics. The relation between the encounter frequency and the number of x-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters. PMID:20404204

  16. Globular cluster x-ray sources

    PubMed Central

    Pooley, David

    2010-01-01

    Globular clusters and x-ray astronomy have a long and fruitful history. Uhuru and OSO-7 revealed highly luminous (> 1036 ergs-1) x-ray sources in globular clusters, and Einstein and ROSAT revealed a larger population of low-luminosity (< 1033 ergs-1) x-ray sources. It was realized early on that the high-luminosity sources were low-mass x-ray binaries in outburst and that they were orders of magnitude more abundant per unit mass in globular clusters than in the rest of the galaxy. However, the low-luminosity sources proved difficult to classify. Many ideas were put forth—low-mass x-ray binaries in quiescence (qLMXBs), cataclysmic variables (CVs), active main-sequence binaries (ABs), and millisecond pulsars (MSPs)—but secure identifications were scarce. In ROSAT observations of 55 clusters, about 25 low-luminosity sources were found. Chandra has now observed over 80 Galactic globular clusters, and these observations have revealed over 1,500 x-ray sources. The superb angular resolution has allowed for many counterpart identifications, providing clues to the nature of this population. It is a heterogeneous mix of qLMXBs, CVs, ABs, and MSPs, and it has been shown that the qLMXBs and CVs are both, in part, overabundant like the luminous LMXBs. The number of x-ray sources in a cluster correlates very well with its encounter frequency. This points to dynamical formation scenarios for the x-ray sources and shows them to be excellent tracers of the complicated internal dynamics. The relation between the encounter frequency and the number of x-ray sources has been used to suggest that we have misunderstood the dynamical states of globular clusters. PMID:20404204

  17. Density of BCR-2 basalt glass at high pressure by X-ray Absorption Microtomography

    NASA Astrophysics Data System (ADS)

    Clark, A. N.; Lesher, C. E.; Gaudio, S. J.; Yamada, A.; Wang, Y.

    2009-12-01

    Improved understanding of compressibility and thermal expansion and their integral properties, density and volume, of basaltic liquids are important for modeling the thermodynamics of partial melting and crystallization, and melt migration in the Earth’s crust and mantle. We are using X-ray absorption in conjunction with microtomography to determine density of basalt glass/melt at high pressures from the linear attenuation coefficient of voxels calibrated using internal calibration standards at monochromatic energy. Experiments are conducted with the rotating anvil apparatus on the 13-BM-D beamline at the Advanced Photon Source, Argonne National Laboratory in an opposing anvil (Drickamer) assembly with 4 mm truncations and 20o taper. The sample and standards are contained within a single crystal diamond sleeve capped with Mo lids inserted into a graphite box-type heater with Mo leads and surrounded by pyrophillite, zirconia and a composite boron epoxy-diamond epoxy--pyrophillite gasket. Pressure is determined by using energy dispersive X-ray diffraction of MgO and Au contained within the capsule. Temperature is controlled to within ±25 oC by regulating power to the heater based on prior calibration. The density of USGS standard BCR-2 (Columbia River Basalt) glass is determined by this technique up to 3 GPa at room temperature giving a compressibility (Ko) for the glass of 70 ±5 GPa, assuming K’= 4. The cell was successfully heated to 900 oC at 1 GPa with tomographic data sets collected at 200 oC temperature intervals. The variation in density with temperature gives a thermal expansion for BCR-2 glass of 3x10-5 K-1. Success in performing microtomography under simultaneous high pressure-temperature conditions will enable this technique to be extended to the melting interval for basalt at elevated pressures in the near future.

  18. X-ray phase-contrast methods

    NASA Astrophysics Data System (ADS)

    Lider, V. V.; Kovalchuk, M. V.

    2013-11-01

    This review is devoted to a comparative description of the methods for forming X-ray phase-contrast images of weakly absorbing (phase) objects. These include the crystal interferometer method, the Talbot interferometer method, diffraction-enhanced X-ray imaging, and the in-line method. The potential of their practical application in various fields of science and technology is discussed. The publications on the development and optimization of X-ray phase-contrast methods and the experimental study of phase objects are analyzed.

  19. X-ray emission from Centaurus A

    SciTech Connect

    Terrell, N.J.

    1981-01-01

    Observations of 3 to 12 keV x-ray emission from NGC 5128 (Cen A) were made by Vela spacecraft over the period 1969 to 1979. These data are in good agreement with previously reported data, but are much more complete. Numerous peaks of x-ray intensity occurred during the period 1973 to 1975, characterized by rapid increases and equally rapid decreases (in less than 10 days). Thus it seems probable that most of the x-ray flux from the nucleus of Cen A came from a single source of small size.

  20. Large Area X-Ray Spectroscopy Mission

    NASA Technical Reports Server (NTRS)

    Tananbaum, H.

    1997-01-01

    The Large Area X-ray Spectroscopy (LAXS) mission concept study continues to evolve strongly following the merging of the LAXS mission with the Next Generation X-ray Observatory (NGXO, PI: Nick White) into the re-named High Throughput X-ray Spectroscopy (HTXS) Mission. HTXS retains key elements of the LAXS proposal, including the use of multiple satellites for risk-reduction and cost savings. A key achievement of the program has been the recommendation by the Structure and Evolution of the Universe (SEUS) (April 1997) for a new start for the HTXS mission in the 2000-2004 timeframe.

  1. X-ray streak crystal spectography

    SciTech Connect

    Kauffman, R.L.; Brown, T.; Medecki, H.

    1983-07-01

    We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11/sup 0/ to 38/sup 0/ and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/..delta..E > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given.

  2. Diffractive Imaging Using Partially Coherent X Rays

    SciTech Connect

    Whitehead, L. W.; Williams, G. J.; Quiney, H. M.; Vine, D. J.; Dilanian, R. A.; Flewett, S.; Nugent, K. A.; Peele, A. G.; Balaur, E.; McNulty, I. [School of Physics, The University of Melbourne, Victoria 3010 (Australia); Department of Physics, La Trobe University, Bundoora, Victoria 3086 (Australia); Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois, 60439 (United States)

    2009-12-11

    The measured spatial coherence characteristics of the illumination used in a diffractive imaging experiment are incorporated in an algorithm that reconstructs the complex transmission function of an object from experimental x-ray diffraction data using 1.4 keV x rays. Conventional coherent diffractive imaging, which assumes full spatial coherence, is a limiting case of our approach. Even in cases in which the deviation from full spatial coherence is small, we demonstrate a significant improvement in the quality of wave field reconstructions. Our formulation is applicable to x-ray and electron diffraction imaging techniques provided that the spatial coherence properties of the illumination are known or can be measured.

  3. On the X-rays of permutations

    E-print Network

    Cecilia Bebeacua; Toufik Mansour; Alexander Postnikov; Simone Severini

    2005-06-16

    The X-ray of a permutation is defined as the sequence of antidiagonal sums in the associated permutation matrix. X-rays of permutation are interesting in the context of Discrete Tomography since many types of integral matrices can be written as linear combinations of permutation matrices. This paper is an invitation to the study of X-rays of permutations from a combinatorial point of view. We present connections between these objects and nondecreasing differences of permutations, zero-sum arrays, decomposable permutations, score sequences of tournaments, queens' problems and rooks' problems.

  4. Tissue chemical analysis with muonic x rays.

    PubMed

    Hutson, R L; Reidy, J J; Springer, K; Daniel, H; Knowles, H B

    1976-07-01

    The stopped muon channel at the Clinton P. Anderson Meson Physics Facility was used as a source of muons for studying the elemental composition of tissue via muonic x rays. The x-ray spectra from several types of tissue were used to determine the amounts of carbon, nitrogen, and oxygen present. These determinations agree with the results of more conventional chemical analysis. Muonic x rays offer a noninvasive technique for determining the amounts of the more abundant elements in selected regions of the body. PMID:935447

  5. X-ray dichroism in noncentrosymmetric crystals

    NASA Astrophysics Data System (ADS)

    Carra, Paolo; Jerez, Andrés; Marri, Ivan

    2003-01-01

    In this paper the authors analyze near-edge absorption of x rays in noncentrosymmetric crystals. The work is motivated by recent observations of x-ray dichroic effects which stem from parity-nonconserving electron interactions. We provide a theoretical description of these experiments and show that they are sensitive to microscopic polar and magnetoelectric properties of the sample. Our derivation extends previous theoretical work on centrosymmetric systems and identifies interesting directions in the microscopic analysis of crystalline materials using x-ray-absorption spectroscopy.

  6. Dental x-ray use in Boston.

    PubMed Central

    Stolurow, K A; Moeller, D W

    1979-01-01

    A telephone survey of 40 dental offices in Boston, Massachusetts, revealed that 95 per cent perform x-ray procedures as part of the initial examination of a new patient, that almost one-half (47.5 per cent) routinely include a full-mouth x-ray series in the initial examination, and that 85 per cent include some type of radiographic procedure as part of the periodic visits for cleaning and checkups. These percentages are substantially in excess of those reported by other investigators in which the respondents were aware that their policies with respect to the use of x-rays were being evaluated. PMID:453399

  7. The Future of X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.

    2013-01-01

    The most important next step is the development of X-ray optics comparable to (or better than) Chandra in angular resolution that far exceed Chandra s effective area. Use the long delay to establish an adequately funded, competitive technology program along the lines I have recommended. Don't be diverted from this objective, except for Explorer-class missions. Progress in X-ray optics, with emphasis on the angular resolution, is central to the paradigm-shifting discoveries and the contributions of X-ray astronomy to multiwavelength astrophysics over the past 51 years.

  8. X-ray Interferometer Using Prism Optics

    SciTech Connect

    Suzuki, Yoshio [JASRI/SPring-8 Mikazuki, Hyogo 6791-5198 (Japan)

    2004-05-12

    Two-beam X-ray interferometer using refractive optics has been developed. A prism made of acrylic resin is used as the beam deflector for hard X-ray wavefront dividing interferometer. This configuration is the same as that of the Fresnel's bi-prism interferometer or the Leith-Upatnieks type two-beam holography in visible light region. Therefore, quantitative analysis of the degree of transversal coherence can be performed by measuring the visibility of interference fringes. It is also possible to realize two-beam holographic imaging in hard X-ray regions.

  9. X-ray emission from protostars

    NASA Astrophysics Data System (ADS)

    Koyama, K.

    I present the results of our Chandra deep exposure observations on star form- ing regions, rho-Ophiuchi and Orion Molecular Clouds 2 and 3. The results are; (1) class I protostars are found to exhibit higher temperature plasma than those of T Tauri stars, (2) X-ray spectra of protostars often show the 6.4 keV fluorescent iron line, strong evidence of dense gas or accretion disk around the star, (3) heavily absorbed X-rays are discovered from the cloud cores, candi- dates of class 0 protostars, (4) young brown dwarfs emit X-rays similar to those of low-mass young stars.

  10. X-ray microscopy using synchrotron radiation

    SciTech Connect

    Jones, K.W.; Gordon, B.M.; Hanson, A.L.; Pounds, J.G.; Rivers, M.L.; Schidlovsky, G.; Smith, J.V.; Spanne, P.; Sutton, S.R.

    1989-01-01

    The system for x-ray microscopy now being developed at the X-26 beam line of the Brookhaven National Synchrotron Light Source (NSLS) is described here. Examples of the use of x-ray microscopy for trace element geochemistry, biology and medicine, and materials investigations are given to emphasize the scientific applications of the technique. Future directions for the improvement and further development of the X-26 microscope and of the x-ray microscopy field in general are discussed. 11 refs., 7 figs.

  11. Statistical Reconstruction Algorithms for Polyenergetic X-ray Computed

    E-print Network

    Fessler, Jeffrey A.

    Statistical Reconstruction Algorithms for Polyenergetic X-ray Computed Tomography by Idris A . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II. X-ray Computed Tomography . . . . . . . . . . . . . . . . . . . 8 2.1 Computed Tomography Basics . . . . . . . . . . . . . . . . . 8 2.2 X-ray Physics

  12. Towards a nanoscale mammographic contrast agent: development of a modular pre-clinical dual optical/x-ray agent

    NASA Astrophysics Data System (ADS)

    Hill, Melissa L.; Gorelikov, Ivan; Niroui, Farnaz; Levitin, Ronald B.; Mainprize, James G.; Yaffe, Martin J.; Rowlands, J. A.; Matsuura, Naomi

    2013-08-01

    Contrast-enhanced digital mammography (CEDM) can provide improved breast cancer detection and characterization compared to conventional mammography by imaging the effects of tumour angiogenesis. Current small-molecule contrast agents used for CEDM are limited by a short plasma half-life and rapid extravasation into tissue interstitial space. To address these limitations, nanoscale agents that can remain intravascular except at sites of tumour angiogenesis can be used. For CEDM, this agent must be both biocompatible and strongly attenuate mammographic energy x-rays. Nanoscale perfluorooctylbromide (PFOB) droplets have good x-ray attenuation and have been used in patients for other applications. However, the macroscopic scale of x-ray imaging (50-100 µm) is inadequate for direct verification that PFOB droplets localize at sites of breast tumour angiogenesis. For efficient pre-clinical optimization for CEDM, we integrated an optical marker into PFOB droplets for microscopic assessment (?50 µm). To develop PFOB droplets as a new nanoscale mammographic contrast agent, PFOB droplets were labelled with fluorescent quantum dots (QDs). The droplets had mean diameters of 160 nm, fluoresced at 635 nm and attenuated x-ray spectra at 30.5 keV mean energy with a relative attenuation of 5.6 ± 0.3 Hounsfield units (HU) mg-1 mL-1 QD-PFOB. With the agent loaded into tissue phantoms, good correlation between x-ray attenuation and optical fluorescence was found (R2 = 0.96), confirming co-localization of the QDs with PFOB for quantitative assessment using x-ray or optical methods. Furthermore, the QDs can be removed from the PFOB agent without affecting its x-ray attenuation or structural properties for expedited translation of optimized PFOB droplet formulations into patients.

  13. "X-Ray Transients in Star-Forming Regions" and "Hard X-Ray Emission from X-Ray Bursters"

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Kaaret, Philip

    1999-01-01

    This grant funded work on the analysis of data obtained with the Burst and Transient Experiment (BATSE) on the Compton Gamma-Ray Observatory. The goal of the work was to search for hard x-ray transients in star forming regions using the all-sky hard x-ray monitoring capability of BATSE. Our initial work lead to the discovery of a hard x-ray transient, GRO J1849-03. Follow-up observations of this source made with the Wide Field Camera on BeppoSAX showed that the source should be identified with the previously known x-ray pulsar GS 1843-02 which itself is identified with the x-ray source X1845-024 originally discovered with the SAS-3 satellite. Our identification of the source and measurement of the outburst recurrence time, lead to the identification of the source as a Be/X-ray binary with a spin period of 94.8 s and an orbital period of 241 days. The funding was used primarily for partial salary and travel support for John Tomsick, then a graduate student at Columbia University. John Tomsick, now Dr. Tomsick, received his Ph.D. from Columbia University in July 1999, based partially on results obtained under this investigation. He is now a postdoctoral research scientist at the University of California, San Diego.

  14. Coherent x-ray lasers for applications

    SciTech Connect

    London, R.A.; Amendt, P.; Rosen, M.D.; Feit, M.D.; Fleck, J.A. (Lawrence Livermore National Lab., CA (USA)); Strauss, M. (Negev Nuclear Research Centre, Beersheba (Israel))

    1990-12-01

    Many of the projected applications of x-ray lasers require high quality output radiation with properties such as short wavelength, high power, good focusability, short pulse, and high degree of coherence. We discuss the requirements of an x-ray laser for the application of holography of biological samples. We present ideas for achieving these properties. Given that population inversions can be established to provide laser gain, we discuss how the propagation and amplification of x-rays within the lasing medium affect the quality of the output radiation. Particular attention is given toward the development of transverse coherence. Results are presented from several methods for calculating the coherence, including a modal analysis and a numerical-wave propagation code. Calculations of the expected degree of coherence of standard x-ray lasers are given, as well as designs for more coherent lasers. 9 refs., 6 figs., 1 tab.

  15. Tsinghua Thomson scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Tang, Chuanxiang; Huang, Wenhui; Li, Renkai; Du, Yingchao; Yan, Lixin; Shi, Jiaru; Du, Qiang; Yu, Peicheng; Chen, Huaibi; Du, Taibin; Cheng, Cheng; Lin, Yuzheng

    2009-09-01

    We proposed the Tsinghua Thomson scattering X-ray (TTX) source as an ultra-fast, high flux source for advanced X-ray imaging studies and applications. A linac system, which consists of an S-band photocathode RF gun, a SLAC type 3 m traveling wave tube and two X-band structures, generates ultra-short, high brightness electron pulses to scatter with tera-watt femto-second laser pulses. A compact low energy electron storage ring is also designed to dramatically enhance the average X-ray flux. In this paper, we present the simulation studies and optimized parameters of the electron and X-ray pulses. The construction and commissioning status of TTX is also reported.

  16. Ultrafast semiconductor x-ray detector

    NASA Astrophysics Data System (ADS)

    Baker, K. L.; Stewart, R. E.; Steele, P. T.; Vernon, S. P.; Hsing, W. W.

    2012-07-01

    The National Ignition Campaign has the goal of developing a burning plasma platform producing up to ˜1019 neutrons in ˜20 picoseconds, ps. Diagnosis will require instruments operating with a time resolution of a few ps within this extremely large neutron flux environment. A diagnostic, which performs an ultrafast conversion of the x-ray signals into the optical regime, has been developed using a linearly chirped probe beam to measure the temporal history of the x-ray pulse. This diagnostic technique was tested on a laser-produced x-ray source and obtained a measurement of the full-width-at-half-maximum, FWHM, of the x-ray pulse of ˜7.2 ps.

  17. X-ray Emission from Massive Stars

    E-print Network

    Cohen, David

    -ray Observatory ­ high-resolution x-ray spectroscopy: measuring Doppler broadening in emission lines Testing pot of water #12;More granulation movies #12;Sinister-looking sunspot, with granulation visible around

  18. X-ray transients in quiescence

    E-print Network

    Sergio Campana

    2000-12-04

    Transient X-ray binaries remain in their quiescent state for a long time (months to hundred years) and then bright up as the most powerful sources of the X-ray sky. While it is clear that, when in outbursts, transient binaries are powered by accretion, the origin of the low luminosity X-ray emission that has been detected in the quiescent state has different interpretations and provides the unique opportunity for testing different accretion regimes. In this paper we concentrate on the various aspects of the accretion physics at low rates onto compact objects. We describe the observational panorama of quiescent emission for the three classes of X-ray transients and try to interpret these data in light of the different regimes accessible at such low mass inflow rates.

  19. Massively parallel X-ray holography

    NASA Astrophysics Data System (ADS)

    Marchesini, Stefano; Boutet, Sébastien; Sakdinawat, Anne E.; Bogan, Michael J.; Bajt, Saša; Barty, Anton; Chapman, Henry N.; Frank, Matthias; Hau-Riege, Stefan P.; Szöke, Abraham; Cui, Congwu; Shapiro, David A.; Howells, Malcolm R.; Spence, John C. H.; Shaevitz, Joshua W.; Lee, Joanna Y.; Hajdu, Janos; Seibert, Marvin M.

    2008-09-01

    Advances in the development of free-electron lasers offer the realistic prospect of nanoscale imaging on the timescale of atomic motions. We identify X-ray Fourier-transform holography as a promising but, so far, inefficient scheme to do this. We show that a uniformly redundant array placed next to the sample, multiplies the efficiency of X-ray Fourier transform holography by more than three orders of magnitude, approaching that of a perfect lens, and provides holographic images with both amplitude- and phase-contrast information. The experiments reported here demonstrate this concept by imaging a nano-fabricated object at a synchrotron source, and a bacterial cell with a soft-X-ray free-electron laser, where illumination by a single 15-fs pulse was successfully used in producing the holographic image. As X-ray lasers move to shorter wavelengths we expect to obtain higher spatial resolution ultrafast movies of transient states of matter.

  20. X-Ray Background Survey Spectrometer (XBSS)

    NASA Technical Reports Server (NTRS)

    Sanders, W. T. (Principal Investigator); Paulos, R. J.

    1996-01-01

    The objective of this investigation was to perform a spectral survey of the low energy diffuse X-ray background using the X-ray Background Survey Spectrometer (XBSS) on board the Space Station Freedom (SSF). XBSS obtains spectra of the X-ray diffuse background in the 11-24 A and 44-84 A wavelength intervals over the entire sky with 15 deg spatial resolution. These X-rays are almost certainly from a very hot (10(exp 6) K) component of the interstellar medium that is contained in regions occupying a large fraction of the interstellar volume near the Sun. Astrophysical plasmas near 10(exp 6) K are rich in emission lines, and the relative strengths of these lines, besides providing information about the physical conditions of the emitting gas, also provide information about its history and heating mechanisms.

  1. Applied X-ray computed tomography

    NASA Astrophysics Data System (ADS)

    Buynak, C. F.; Bossi, R. H.

    1995-05-01

    The application of X-ray computed tomography (CT) for aircraft and aerospace structures and ancillary equipment has been investigated in the Advanced Development of X-Ray Computed Tomography Applications demonstration (CTAD) program sponsored by the NDE Branch of the Materials Directorate at the Air Force Wright Laboratory. The volumetric feature evaluation capability of X-ray CT offers a quantitative measurement tool for material density/constituents and dimensions. This capability has economic value for improving the evaluation and control of materials and processes used in aircraft/aerospace structures. The CTAD effort has applied CT in a variety of areas such as electronics, closed systems, castings, organic composites and advanced materials and processes, using a wide range of X-ray sources from less than 150 kV to 9 MV. Applications of CT in these areas include configuration control, anomaly detection, geometry acquisition, failure analysis, noninvasive micrography, product development support and engineering fitness for service.

  2. Spectra of cosmic X-ray sources

    NASA Technical Reports Server (NTRS)

    Holt, S. S.; Mccray, R.

    1982-01-01

    X-ray measurements provide the most direct probes of astrophysical environments with temperatures exceeding one million K. Progress in experimental research utilizing dispersive techniques (e.g., Bragg and grating spectroscopy) is considerably slower than that in areas utilizing photometric techniques, because of the relative inefficiency of the former for the weak X-ray signals from celestial sources. As a result, the term "spectroscopy" as applied to X-ray astronomy has traditionally satisfied a much less restrictive definition (in terms of resolving power) than it has in other wavebands. Until quite recently, resolving powers of order unity were perfectly respectable, and still provide (in most cases) the most useful spectroscopic data. In the broadest sense, X-ray photometric measurements are spectroscopic, insofar as they represent samples of the overall electromagnetic continua of celestial objects.

  3. X-ray source for mammography

    DOEpatents

    Logan, C.M.

    1994-12-20

    An x-ray source is described utilizing anode material which shifts the output spectrum to higher energy and thereby obtains higher penetrating ability for screening mammography application, than the currently utilized anode material. The currently used anode material (molybdenum) produces an energy x-ray spectrum of 17.5/19.6 keV, which using the anode material of this invention (e.g. silver, rhodium, and tungsten) the x-ray spectrum would be in the 20-35 keV region. Thus, the anode material of this invention provides for imaging of breasts with higher than average x-ray opacity without increase of the radiation dose, and thus reduces the risk of induced breast cancer due to the radiation dose administered for mammograms. 6 figures.

  4. X-rays from colliding stellar winds

    NASA Technical Reports Server (NTRS)

    Luo, Ding; Mccray, Richard; Mac Low, Mordecai-Mark

    1990-01-01

    A stellar wind from a massive OB or Wolf-Rayet star in a binary system will strike the surface or stellar wind of its companion, forming shocked gas that can radiate X-rays. The X-ray spectrum from the shocked winds will vary in a predictable way with orbital phase, owing to photoelectric absorption by the stellar winds. Detailed models are calculated for the hydrodynamics and X-ray emission from two such systems. In one of these systems (HD 165052), the winds are nearly identical in strength. In the other (V444 Cygni), the wind of the Wolf-Rayet star overwhelms and crushes that of its companion. The calculated X-ray luminosities agree fairly well with the observed values for HD 165052 and for V444 Cygni. These results can be scaled to other such systems.

  5. Low-mass X-ray binaries

    NASA Technical Reports Server (NTRS)

    Mcclintock, J. E.; Rappaport, S. A.

    1985-01-01

    A review is given of current understanding of low-mass X-ray binaries (LMXBs), which are luminous X-ray sources composed of a late-type optical companion (mass less than about 1 solar mass) and a neutron star (or possibly a black hole). Thirty-two LMXBs have been identified with optical counterparts in the Galaxy and one in the Large Magellanic Cloud (Brad and McClintock, 1983). It is unlikely that there are more than about 100 active LMXBs in the Galaxy, compared with about 200,000 cataclysmic variables. Topics covered in the review are: typical X-ray and optical properties; orbital periods; the nature of the compact source; accretion disks; formation; mass transfer mechanisms; and globular clusters and bright bulge X-ray sources.

  6. Chandra X-Ray Observatory Center

    NSDL National Science Digital Library

    This week, Space Shuttle mission STS-93 deployed the Chandra X-Ray Observatory, the world's most powerful X-Ray telescope. The third of NASA's "Great Observatories," the Chandra X-Ray Observatory will study X-Rays rather than visible light (the Hubble Space Telescope) or gamma rays (the Compton Gamma Ray Observatory). This site offers overviews and news of the Observatory and its mission. Operated for NASA by the Harvard-Smithsonian Center for Astrophysics, this site provides resources for students, scientists, the press, and general users. In the Public Information and Education section, users will find photos, a field guide, and educational materials. The Scientific User Support Section includes detailed target information, various documents, newsletters, and information on the Emission Line Project (ELP). In addition, the site provides breaking mission news, links to live video feeds, telemetry diagrams, and a timeline.

  7. Impulsive solar X-ray bursts

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Frost, K. J.; Maetzler, C.; Ohki, K.; Saba, J. L.

    1977-01-01

    A set of 22 simple, impulsive solar flares, identified in the OSO-5 hard X-ray data, were analyzed together with coincident microwave and meterwave radio observations. The rise times and fall times of the X-ray bursts are found to be highly correlated and effectively equal, strongly suggesting a flare energizing mechanism that is reversible. The good time resolution available for these observations reveals that the microwave emission is influenced by an additional process, evident in the tendency of the microwave emission to peak later and decay more slowly than the symmetric X-ray bursts. Meterwave emission is observed in coincidence with the 5 events which show the strongest time correlation between the X-ray and microwave burst structure. This meterwave emission is characterized by U-burst radiation, indicating confinement of the flare source.

  8. Second order x-ray in-line phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Cong, Wenxiang; Wang, Ge

    2014-09-01

    X-ray phase imaging is sensitive to structural variation of soft tissue, and offers excellent contrast resolution for characterization of cancerous tissues. Also, the cross-section of x-ray phase shift is a thousand times greater than that of x-ray attenuation in soft tissue over the diagnostic energy range, allowing a much higher signal-to-noise ratio at a substantially lower radiation dose than attenuation-based x-ray imaging. In this paper, we present a second order approximation model with respect to phase shift based on the paraxial Fresnel-Kirchhoff diffraction theory, and also discuss in-line dark-field imaging based on the second order model. This proposed model accurately establishes a quantitative correspondence between phases and recorded intensity images, outperforming the linear phase approximation model widely used in the conventional methods of x-ray in-line phase-contrast imaging. This new model can be iteratively solved using the algebraic reconstruction technique (ART). The state of the art compressive sensing ingredients can be incorporated to achieve high quality image reconstruction. Our numerical simulation studies demonstrate the feasibility of the proposed approach that is more accurate and stable, and more robust against noise than the conventional approach.

  9. Neutron radiography; Key to secrets that x-rays can't see

    SciTech Connect

    Aderhold, H.C. (Cornell Univ., Ithaca, NY (United States). Ward Lab.)

    1992-01-01

    This paper discusses neutron radiography which produces images that look much like x-rays. But what they reveal is, in many ways, just the opposite of what x-rays reveal. Neutron radiography cannot show coins inside a purse or bones concealed by flesh. But it can show a plastic toy behind an inch of lead, oil flowing through a valve, or tiny roots growing through soil. The two types of radiography reveal different things because of a fundamental difference in the way x-rays and thermal neutrons interact with matter. X-rays interact with the electrons in the atoms of which a specimen is composed, and the higher the atomic number and the denser the specimen, the more the x-rays are attenuated. Thermal neutrons are unaffected by the specimen's electron content, since they have no charge. Instead, they interact with the specimen's atomic nuclei, and attenuation of the neutron flux depends on the way the nuclei deflect or absorb neutrons. This varies from one element to another, in ways that have nothing to do with atomic number.

  10. Gold nanoparticles as contrast agents in x-ray imaging and computed tomography.

    PubMed

    Cole, Lisa E; Ross, Ryan D; Tilley, Jennifer Mr; Vargo-Gogola, Tracy; Roeder, Ryan K

    2015-01-01

    Computed tomography enables 3D anatomic imaging at a high spatial resolution, but requires delivery of an x-ray contrast agent to distinguish tissues with similar or low x-ray attenuation. Gold nanoparticles (AuNPs) have gained recent attention as an x-ray contrast agent due to exhibiting a high x-ray attenuation, nontoxicity and facile synthesis and surface functionalization for colloidal stability and targeted delivery. Potential diagnostic applications include blood pool imaging, passive targeting and active targeting, where actively targeted AuNPs could enable molecular imaging by computed tomography. This article summarizes the current state of knowledge for AuNP x-ray contrast agents within a paradigm of key structure-property-function relationships in order to provide guidance for the design of AuNP contrast agents to meet the necessary functional requirements in a particular application. Functional requirements include delivery to the site of interest (e.g., blood, tumors or microcalcifications), nontoxicity during delivery and clearance, targeting or localization at the site of interest and contrast enhancement for the site of interest compared with surrounding tissues. Design is achieved by strategically controlling structural characteristics (composition, mass concentration, size, shape and surface functionalization) for optimized properties and functional performance. Examples from the literature are used to highlight current design trade-offs that exist between the different functional requirements. PMID:25600973

  11. Detection of soft X-ray emission from SMC X-1

    NASA Technical Reports Server (NTRS)

    Bunner, A. N.; Sanders, W. T.

    1979-01-01

    The observation of 0.25-keV X-rays from SMC X-1 by a soft X-ray experiment aboard OSO 8 is reported. The variable soft X-ray source observed is identified with the hard X-ray source SMC X-1 on the basis of a rather abrupt ending to the emission (fall time about 2.5 hr) at the time SMC X-1 was expected to enter eclipse. A source luminosity of about 5 x 10 to the 38th erg/s in the 0.18-0.28-keV range is derived by assuming a distance of 68 kpc and correcting for attenuation by 3.4 x 10 to the 20th H atoms per sq cm of intervening galactic gas; this luminosity is shown to be about a factor of 40 greater than the observed coincident luminosity in the 0.8-3-keV band. The soft X-ray intensity upon emergence from eclipse is found to be reduced by a factor of at least 20 from the peak intensity prior to eclipse. It is suggested that this asymmetry may reflect a geometry in which the soft X-ray source trails the compact star as in an accretion-stream model.

  12. Hard X-ray devices for target detection at longer distances

    NASA Astrophysics Data System (ADS)

    Gertsenshteyn, Michael; Grubsky, Victor; Jannson, Tomasz

    2006-08-01

    Detecting and identifying organic and metallic targets at distances from 50 m to 100 m is difficult for hard X-ray detection devices, especially when targets (such as improvised explosive devices (IEDs)) are concealed behind metal (steel) and non-metal (plastic, wood, rocks, soil, etc.) walls. At least two problems are inherent to detection at such long distances: (1) the air attenuation of X-rays, which can be significant for standoff distances of x = 50 m (100 m total for 2x); and (2) a scattering factor proportional to x 4 that comes from the divergence of X-rays propagating from a source to a target and X-rays backscattering from a target (usually, Compton backscattering in low Z-number materials). The compensation of these factors by novel lobster-eye hard X-ray optics is analyzed in this paper. The analysis and the optimization of the hard X-ray lobster eye lens for realistic parameters are also discussed.

  13. X-Ray Surveys with Chandra

    NASA Technical Reports Server (NTRS)

    Elvis, Martin

    1999-01-01

    The potential of unbiased high galactic latitude surveys in X-rays with Chandra will be laid out. The specifics of the surveys approved for AO1 (GO+GTO) will be used to predict source numbers and accuracy in the very soft, 'ROSAT', and hard X-ray bands. If Chandra flight data is available by the time of the meeting examples will be shown and actual performance compared with predictions.

  14. X-ray interferometry with microelectronvolt resolution.

    PubMed

    Shvyd'ko, Yu V; Lerche, M; Wille, H-C; Gerdau, E; Lucht, M; Rüter, H D; Alp, E E; Khachatryan, R

    2003-01-10

    We demonstrate an interferometer for hard x rays with two back-reflecting sapphire crystal mirrors--a prototype x-ray Fabry-Pérot interferometer. A finesse of 15 and 0.76 mu eV broad Fabry-Pérot transmission resonances are measured by the time response of the interferometer. Interference patterns are observed directly in spectral dependences of reflectivity. PMID:12570613

  15. A normal incidence X-ray telescope

    NASA Technical Reports Server (NTRS)

    Golub, Leon

    1987-01-01

    The postflight performance evaluation of the X-ray telescope was summarized. All payload systems and subsystems performed well within acceptable limits, with the sole exception of the light-blocking prefilters. Launch, flight and recovery were performed in a fully satisfactory manner. The payload was recovered in a timely manner and in excellent condition. The prefilter performance analysis showed that no X-ray images were detected on the processed flight film. Recommendations for improved performance are listed.

  16. Theories of accreting x-ray pulsars

    SciTech Connect

    Meszaros, P.

    1984-05-26

    We review current models of X-ray pulsars in the light of our observational knowledge. The physics of the accretion column and the polar cap are discussed, and the main physical processes described, emphasizing the peculiarities introduced by the strong magnetic field. Radiative transfer methods adapted to these extreme conditions are outlined. We then discuss recent calculations on the self-consistent structure of the X-ray emission region, aimed at providing realistic theoretical spectra and pulse shapes.

  17. A multichannel X-ray detector

    Microsoft Academic Search

    H. C. Gerritsen; H. van Brug; F. Bijkerk; M. J. van der Wiel

    1986-01-01

    A multichannel X-ray detector with a spatial resolution of 0.13 mm and a maximum of 200 effective channels is described. The detector consists of a conversion electrode to convert X-rays into electrons, a microchannel-plate\\/phosphor-screen assembly to amplify the electron signal, a self-scanning array containing 1024 photodiodes, and optics to form an image from the phosphor screen on the self-scanning array.

  18. Lacquer polishing of X-ray optics

    NASA Technical Reports Server (NTRS)

    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.

  19. X-ray tube with axial focusing

    Microsoft Academic Search

    V. L. Kuznetsov; D. S. Skomorokhov; A. L. Filatov

    2008-01-01

    A dc X-ray tube based on an immersion lens has been designed. The tube consists of electrodes with axial symmetry, a directly\\u000a heated cathode, and a cylindrical anode; it has a front radiation output and small sizes. 50 and 100 W X-ray tubes and a 1.2\\u000a kW demountable tube with a dual Al-Mg anode were designed, running tests were performed,

  20. Ultrahigh-resolution X-ray tomography

    Microsoft Academic Search

    W. S. Haddad; J. E. Trebes; R. A. Levesque; I. McNulty; L. Yang; E. H. Anderson

    1994-01-01

    Ultrahigh-resolution three-dimensional images of a microscopic test object were made with soft x-rays collected with a scanning transmission x-ray microscope. The test object consisted of two different patterns of gold bars on silicon nitride windows that were separated by 5 micrometers. Depth resolution comparable to the transverse resolution was achieved by recording nine two-dimensional images of the object at angles

  1. Soft x-ray laser cavities

    SciTech Connect

    Ceglio, N.M.; Stearns, D.G.; Hawryluk, A.M.; Barbee, T.M.; Danzmann, K.; Kuehne, M.; Mueller, P.; Wende, B.; Stearns, M.B.; Petford-Long, A.K.

    1986-07-08

    We report progress in the development of multilayer components for use in multiple pass soft x-ray laser cavities operating in the 100A to 300A spectral range. Our work includes fabrication and characterization of multilayer components; simple resonant cavity design; damage threshold assessment for multilayers in the x-ray laser environment; and multipass cavity experiments for efficiency enhancement and transverse mode selection. 14 refs., 9 figs.

  2. The Uhuru X-Ray Instrument

    Microsoft Academic Search

    N. Jagoda; G. Austin; S. Mickiewicz; R. Goddard

    1972-01-01

    On 12 December 1970, the UHURU (SAS-A) X-ray observatory was launched into equatorial orbit with the prime mission of conducting an all-sky survey of astronomical X-ray sources with intensities of 5 ?? 10-5 Sco-Xl or greater. Featuring two large area proportional counter detector systems, the experiment has operated without a failure and is returning information of great interest to the

  3. ALFT's Soft X-Ray Source Development

    Microsoft Academic Search

    Emilio Panarella

    2002-01-01

    ALFT (www.alft.com) was funded by the Federal and Provincial governments of Canada in 1987 to pursue the objective of making soft X-ray sources for microlithography.For 15 years ALFT has successfully pursued this objective. Recently, the company has found that its sources can complement the synchrotron as provider of soft X-rays for applications that range from biotechnology to nanotechnology.A beam from

  4. Kiloparsec-Scale X-Ray Jets

    Microsoft Academic Search

    C. M. Urry; F. Tavecchio; R. Scarpa; R. Sambruna; L. Maraschi; J. Pesce

    2000-01-01

    Several kiloparsec-scale X-ray jets have now been discovered with the Chandra X-ray Observatory, extending up to ~50 kpc (projected distance) from the active galactic nucleus in which the jet originates. In all cases, these jets also emit radio and optical light, which can be well explained as synchrotron radiation. We suggest that in at least some jets, including those in

  5. Chandra X-ray Observatory Center

    E-print Network

    ,000 light years from Earth in the center of the Milky Way. (Credit: X-ray: NASA/UMass/D.Wang et al., IR arcmin across (about 7.5 light years); Close-up: about 4 arcsec (about 0.5 light year) Chandra X (red and yellow). The inset shows a close-up of Sgr A* in X-rays only, covering a region half a light

  6. X-ray Crystallography of Photosynthetic Proteins

    Microsoft Academic Search

    Petra Fromme; James P. Allen

    This chapter provides an overview on the present status of the X-ray structure analysis of photosynthetic proteins. The methods\\u000a and problems of crystallization and X-ray structure analysis of the large photosynthetic protein complexes are discussed.\\u000a In the second part of the chapter, selected structures of the protein complexes are presented and the function of the proteins\\u000a is briefly discussed based

  7. Triple coincidences of x-ray photons

    SciTech Connect

    Ikonen, E.; Holopainen, S. [Metrology Research Institute, Helsinki University of Technology and Centre for Metrology and Accreditation, P.O. Box 3000, FI-02015 TKK (Finland)

    2007-09-15

    An analysis is presented that shows specific features of three-photon coincidences from a synchrotron radiation source and points out that these features are measurable at presently operated, advanced hard-x-ray facilities. Analogies with three-pion correlations of high-energy physics are considered, leading to the conclusion that triple coincidences of x rays can be measured more accurately than the three-pion coincidences.

  8. Real-Time X-Ray Inspection

    NASA Technical Reports Server (NTRS)

    Bulthuis, Ronald V.

    1988-01-01

    X-ray imaging instrument adapted to continuous scanning. Modern version of fluoroscope enables rapid x-ray inspection of parts. Developed for detection of buckling in insulated ducts. Uses radiation from radioactive gadolinium or thallium source. Instrument weighs only 6 1/2 lb. Quickly scanned by hand along duct surface, providing real-time image. Based on Lixiscope, developed at Goddard Space Flight Center.

  9. High speed gated x-ray imagers

    SciTech Connect

    Kilkenny, J.D.; Bell, P.; Hanks, R.; Power, G.; Turner, R.E.; Wiedwald, J.

    1988-01-01

    Single and multi-frame gated x-ray images with time-resolution as fast as 150 psec are described. These systems are based on the gating of microchannel plates in a stripline configuration. The gating voltage comes from the avalanche breakdown of reverse biased p-n junction producing high power voltage pulses as short as 70 psec. Results from single and four frame x-ray cameras used on Nova are described. 8 refs., 9 figs.

  10. Development of x-ray laminography under an x-ray microscopic condition.

    PubMed

    Hoshino, Masato; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yoshio; Yagi, Naoto

    2011-07-01

    An x-ray laminography system under an x-ray microscopic condition was developed to obtain a three-dimensional structure of laterally-extended planar objects which were difficult to observe by x-ray tomography. An x-ray laminography technique was introduced to an x-ray transmission microscope with zone plate optics. Three prototype sample holders were evaluated for x-ray imaging laminography. Layered copper grid sheets were imaged as a laminated sample. Diatomite powder on a silicon nitride membrane was measured to confirm the applicability of this method to non-planar micro-specimens placed on the membrane. The three-dimensional information of diatom shells on the membrane was obtained at a spatial resolution of sub-micron. Images of biological cells on the membrane were also obtained by using a Zernike phase contrast technique. PMID:21806188

  11. Development of x-ray laminography under an x-ray microscopic condition

    NASA Astrophysics Data System (ADS)

    Hoshino, Masato; Uesugi, Kentaro; Takeuchi, Akihisa; Suzuki, Yoshio; Yagi, Naoto

    2011-07-01

    An x-ray laminography system under an x-ray microscopic condition was developed to obtain a three-dimensional structure of laterally-extended planar objects which were difficult to observe by x-ray tomography. An x-ray laminography technique was introduced to an x-ray transmission microscope with zone plate optics. Three prototype sample holders were evaluated for x-ray imaging laminography. Layered copper grid sheets were imaged as a laminated sample. Diatomite powder on a silicon nitride membrane was measured to confirm the applicability of this method to non-planar micro-specimens placed on the membrane. The three-dimensional information of diatom shells on the membrane was obtained at a spatial resolution of sub-micron. Images of biological cells on the membrane were also obtained by using a Zernike phase contrast technique.

  12. UNDERSTANDING X-RAY STARS:. The Discovery of Binary X-ray Sources

    NASA Astrophysics Data System (ADS)

    Schreier, E. J.; Tananbaum, H.

    2000-09-01

    The discovery of binary X-ray sources with UHURU introduced many new concepts to astronomy. It provided the canonical model which explained X-ray emission from a large class of galactic X-ray sources: it confirmed the existence of collapsed objects as the source of intense X-ray emission; showed that such collapsed objects existed in binary systems, with mass accretion as the energy source for the X-ray emission; and provided compelling evidence for the existence of black holes. This model also provided the basis for explaining the power source of AGNs and QSOs. The process of discovery and interpretation also established X-ray astronomy as an essential sub-discipline of astronomy, beginning its incorporation into the mainstream of astronomy.

  13. Indus-2 X-ray lithography beamline for X-ray optics and material science applications

    SciTech Connect

    Dhamgaye, V. P., E-mail: vishal@rrcat.gov.in; Lodha, G. S., E-mail: vishal@rrcat.gov.in [Indus Synchrotrons Utilisation Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

    2014-04-24

    X-ray lithography is an ideal technique by which high aspect ratio and high spatial resolution micro/nano structures are fabricated using X-rays from synchrotron radiation source. The technique has been used for fabricating optics (X-ray, visible and infrared), sensors and actuators, fluidics and photonics. A beamline for X-ray lithography is operational on Indus-2. The beamline offers wide lithographic window from 1-40keV photon energy and wide beam for producing microstructures in polymers upto size ?100mm × 100mm. X-ray exposures are possible in air, vacuum and He gas environment. The air based exposures enables the X-ray irradiation of resist for lithography and also irradiation of biological and liquid samples.

  14. Advanced enrichment monitoring technology based on transmission measurements with an X-ray source and NaI(Tl) spectrometer

    Microsoft Academic Search

    K. D. Ianakiev; B. D. Boyer; J. M. Goda; T. R. Hill; C. E. Moss; H. Nguyen; R. F. Parker; M. T. Paffett; B. P. Nolen; M. T. Swinhoe

    2009-01-01

    In this paper we report our progress toward the development of an advanced enrichment monitoring technology for safeguarding gas centrifuge enrichment plants. We compare the UF6 gas pipe attenuation and sensitivity to X-ray tube HV variations for two transmission energies: 22 keV and 25.5 keV. The first experimental enrichment results taken with a static UF6 gaseous source and X-ray tube

  15. Generation of picosecond CuK? X-ray pulses and application to time-resolved X-ray diffraction

    Microsoft Academic Search

    P. Chen; I. V. Tomov; H. E. Elsayed-Ali; M. P. Rentzepis

    1996-01-01

    Summary form only given. Generation of picosecond X-ray pulses has applications to time-resolved diffraction studies. For the generation of picosecond narrow linewidth hard X-ray pulses one can use the optical excitation of an X-ray diode. This technique allows for the generation of picosecond X-ray pulses with spatial and spectral characteristics similar to the X-ray radiation generated by conventional X-ray tubes.

  16. Development and applications of grazing exit micro X-ray fluorescence instrument using a polycapillary X-ray lens

    Microsoft Academic Search

    T. Emoto; Y. Sato; Y. Konishi; X. Ding; K. Tsuji

    2004-01-01

    A polycapillary X-ray lens is an effective optics to obtain a ?m-size X-ray beam for micro-X-ray fluorescence spectrometry (?-XRF). We developed a ?-XRF instrument using a polycapillary X-ray lens, which also enabled us to perform Grazing Exit ?-XRF (GE-?-XRF). The evaluated diameter of the primary X-ray beam was 48 ?m at the focal distance of the X-ray lens. Use of

  17. Spectroscopic Studies in X-ray Astronomy

    NASA Astrophysics Data System (ADS)

    Choi, Chul-Sung

    2000-09-01

    X-ray astronomy deals with measurements of the electromagnetic radiation in the energy range of E 0.1- 100 keV. The wavelength of X-ray is comparable to the size of atoms, so that the photons in the X-ray range are usually produced and absorbed by the atomic processes. Since the launch of the first X-ray astronomy satellite "Uhuru" in 1970, technological advances in a launch capability and a detection capability make X-ray astronomy one of the most rapidly evolving fields of astronomical research. Particularly, a spectral resolving power E/Delta E has been increased by an order of 2 - 3 (in the energy range of 0,1 - 10 keV) during the past 30 years. In this paper, I briefly review a developing process of the resolving power and spectroscopic techniques. Then I describe important emission/absorption lines in X-ray astronomy, as well as diagnostics of gas property with line parameters.

  18. Optics Developments for X-Ray Astronomy

    NASA Technical Reports Server (NTRS)

    Ramsey, Brian

    2014-01-01

    X-ray optics has revolutionized x-ray astronomy. The degree of background suppression that these afford, have led to a tremendous increase in sensitivity. The current Chandra observatory has the same collecting area (approx. 10(exp 3)sq cm) as the non-imaging UHURU observatory, the first x-ray observatory which launched in 1970, but has 5 orders of magnitude more sensitivity due to its focusing optics. In addition, its 0.5 arcsec angular resolution has revealed a wealth of structure in many cosmic x-ray sources. The Chandra observatory achieved its resolution by using relatively thick pieces of Zerodur glass, which were meticulously figured and polished to form the four-shell nested array. The resulting optical assembly weighed around 1600 kg, and cost approximately $0.5B. The challenge for future x-ray astronomy missions is to greatly increase the collecting area (by one or more orders of magnitude) while maintaining high angular resolution, and all within realistic mass and budget constraints. A review of the current status of US optics for x-ray astronomy will be provided along with the challenges for future developments.

  19. EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications

    SciTech Connect

    Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory - DIENCA, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory - DIENCA, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, Ferrara University, via Saragat 1, I-44122 Ferrara (Italy); Mariotti, F. [ENEA, IRP-DOS, via dei Colli 16, I-40136 Bologna (Italy)

    2012-09-01

    The electron beam emitted from the back of Plasma Focus devices is being studied as a radiation source for intraoperative radiation therapy applications. A Plasma Focus device is being developed to this aim, to be utilized as an x-ray source. The electron beam is driven to impinge on 50 {mu}m brass foil, where conversion x-rays are generated. Measurements with gafchromic film are performed to analyse the attenuation of the x-rays beam and to predict the dose given to the culture cell in radiobiological experiments to follow.

  20. Demonstration of phase-contrast X-ray computed tomography using an X-ray interferometer

    Microsoft Academic Search

    A. Momose

    1995-01-01

    Phase-contrast X-ray computed tomography (PCX-CT) using an X-ray interferometer is introduced for observing a density distribution inside an organic material. PCX-CT images are compared with an absorption-contrast X-ray CT image and shown to be highly sensitive. To convert an interference pattern into an image of phase-shift distribution, which is put into a CT algorithm, the author applied subfringe analysis techniques,