Nanometer-scale characterization of laser-driven compression, shocks, and phase transitions, by x-ray scattering using free electron lasers

DOE PAGES

Kluge, T.; Rödel, C.; Rödel, M.; ...

2017-10-23

In this paper, we study the feasibility of using small angle X-ray scattering (SAXS) as a new experimental diagnostic for intense laser-solid interactions. By using X-ray pulses from a hard X-ray free electron laser, we can simultaneously achieve nanometer and femtosecond resolution of laser-driven samples. This is an important new capability for the Helmholtz international beamline for extreme fields at the high energy density endstation currently built at the European X-ray free electron laser. We review the relevant SAXS theory and its application to transient processes in solid density plasmas and report on first experimental results that confirm the feasibilitymore » of the method. Finally, we present results of two test experiments where the first experiment employs ultra-short laser pulses for studying relativistic laser plasma interactions, and the second one focuses on shock compression studies with a nanosecond laser system.« less

Nanometer-scale characterization of laser-driven compression, shocks, and phase transitions, by x-ray scattering using free electron lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kluge, T.; Rödel, C.; Rödel, M.

In this paper, we study the feasibility of using small angle X-ray scattering (SAXS) as a new experimental diagnostic for intense laser-solid interactions. By using X-ray pulses from a hard X-ray free electron laser, we can simultaneously achieve nanometer and femtosecond resolution of laser-driven samples. This is an important new capability for the Helmholtz international beamline for extreme fields at the high energy density endstation currently built at the European X-ray free electron laser. We review the relevant SAXS theory and its application to transient processes in solid density plasmas and report on first experimental results that confirm the feasibilitymore » of the method. Finally, we present results of two test experiments where the first experiment employs ultra-short laser pulses for studying relativistic laser plasma interactions, and the second one focuses on shock compression studies with a nanosecond laser system.« less

X-ray absorption and reflection as probes of the GaN conduction bands: Theory and experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lambrecht, W.R.L.; Rashkeev, S.N.; Segall, B.

1997-04-01

X-ray absorption measurements are a well-known probe of the unoccupied states in a material. The same information can be obtained by using glancing angle X-ray reflectivity. In spite of several existing band structure calculations of the group III nitrides and previous optical studies in UV range, a direct probe of their conduction band densities of states is of interest. The authors performed a joint experimental and theoretical investigation using both of these experimental techniques for wurtzite GaN.

Rat Phantom Depth Dose Studies in Electron, X-ray, Gamma-Ray, and Reactor Radiation Fields

DTIC Science & Technology

1986-12-01

i©™D©/^ ^1[P@^T Rat phantom depth dose studies in electron , Xrayf gamma-ray, and reactor radiation fields M. Dooley D. M. Eagleson G. H. Zeman...energy electrons , bremsstrahlung, and mixed neutron/gamma radiation fields are sometimes used in radiobiological experiments employing rats. This report...have revealed differing sensitivities of experimental animals that have been exposed to cobalt-60 photons, high-energy electrons , high-energy X rays

Experimental Approaches for Solution X-Ray Scattering and Fiber Diffraction

PubMed Central

Irving, T. C.

2008-01-01

X-ray scattering and diffraction from non-crystalline systems have gained renewed interest in recent years, as focus shifts from the structural chemistry information gained by high-resolution studies to the context of structural physiology at larger length scales. Such techniques permit the study of isolated macromolecules as well as highly organized macromolecular assemblies as a whole under near-physiological conditions. Time-resolved approaches, made possible by advanced synchrotron instrumentation, add a critical dimension to many of these investigations. This article reviews experimental approaches in non-crystalline x-ray scattering and diffraction that may be used to illuminate important scientific questions such as protein/nucleic acid folding and structure-function relationships in large macromolecular assemblies. PMID:18801437

Chlorine signal attenuation in concrete.

PubMed

Naqvi, A A; Maslehuddin, M; Ur-Rehman, Khateeb; Al-Amoudi, O S B

2015-11-01

The intensity of prompt gamma-ray was measured at various depths from chlorine-contaminated silica fume (SF) concrete slab concrete specimens using portable neutron generator-based prompt gamma-ray setup. The intensity of 6.11MeV chloride gamma-rays was measured from the chloride contaminated slab at distance of 15.25, 20.25, 25.25, 30.25 and 35.25cm from neutron target in a SF cement concrete slab specimens. Due to attenuation of thermal neutron flux and emitted gamma-ray intensity in SF cement concrete at various depths, the measured intensity of chlorine gamma-rays decreases non-linearly with increasing depth in concrete. A good agreement was noted between the experimental results and the results of Monte Carlo simulation. This study has provided useful experimental data for evaluating the chloride contamination in the SF concrete utilizing gamma-ray attenuation method. Copyright © 2015 Elsevier Ltd. All rights reserved.

Review of the Theoretical and Experimental Status of Dark Matter Identification with Cosmic-Ray Antideuterons

NASA Technical Reports Server (NTRS)

Aramaki, T.; Boggs, S.; Bufalino, S.; Dal, L.; von Doetinchem, P.; Donato, F.; Fornengo, N.; Fuke, H.; Grefe, M.; Hailey, C.;

Review of the theoretical and experimental status of dark matter identification with cosmic-ray antideuterons

DOE PAGES

Aramaki, T.; Boggs, S.; Bufalino, S.; ...

2016-01-27

Recent years have seen increased theoretical and experimental effort towards the first-ever detection of cosmic-ray antideuterons, in particular as an indirect signature of dark matter annihilation or decay. In contrast to indirect dark matter searches using positrons, antiprotons, or γ-rays, which suffer from relatively high and uncertain astrophysical backgrounds, searches with antideuterons benefit from very suppressed conventional backgrounds, offering a potential breakthrough in unexplored phase space for dark matter. This article is based on the first dedicated cosmic-ray antideuteron workshop, which was held at UCLA in June 2014. It reviews broad classes of dark matter candidates that result in detectablemore » cosmic-ray antideuteron fluxes, as well as the status and prospects of current experimental searches. The coalescence model of antideuteron production and the influence of antideuteron measurements at particle colliders are discussed. This is followed by a review of the modeling of antideuteron propagation through the magnetic fields, plasma currents, and molecular material of our Galaxy, the solar system, the Earth’s geomagnetic field, and the atmosphere. Lastly, the three ongoing or planned experiments that are sensitive to cosmic-ray antideuterons, BESS, AMS-02, and GAPS, are detailed. As cosmic-ray antideuteron detection is a rare event search, multiple experiments with orthogonal techniques and backgrounds are essential. Furthermore, the combination of AMS-02 and GAPS antideuteron searches is highly desirable. Many theoretical and experimental groups have contributed to these studies over the last decade, this review aims to provide the first coherent discussion of the relevant dark matter theories that antideuterons probe, the challenges to predictions and interpretations of antideuteron signals, and the experimental efforts toward cosmic antideuteron detection.« less

Single-shot Monitoring of Ultrafast Processes via X-ray Streaking at a Free Electron Laser.

PubMed

Buzzi, Michele; Makita, Mikako; Howald, Ludovic; Kleibert, Armin; Vodungbo, Boris; Maldonado, Pablo; Raabe, Jörg; Jaouen, Nicolas; Redlin, Harald; Tiedtke, Kai; Oppeneer, Peter M; David, Christian; Nolting, Frithjof; Lüning, Jan

2017-08-03

The advent of x-ray free electron lasers has extended the unique capabilities of resonant x-ray spectroscopy techniques to ultrafast time scales. Here, we report on a novel experimental method that allows retrieving with a single x-ray pulse the time evolution of an ultrafast process, not only at a few discrete time delays, but continuously over an extended time window. We used a single x-ray pulse to resolve the laser-induced ultrafast demagnetisation dynamics in a thin cobalt film over a time window of about 1.6 ps with an excellent signal to noise ratio. From one representative single shot measurement we extract a spin relaxation time of (130 ± 30) fs with an average value, based on 193 single shot events of (113 ± 20) fs. These results are limited by the achieved experimental time resolution of 120 fs, and both values are in excellent agreement with previous results and theoretical modelling. More generally, this new experimental approach to ultrafast x-ray spectroscopy paves the way to the study of non-repetitive processes that cannot be investigated using traditional repetitive pump-probe schemes.

Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

PubMed Central

Canton, Sophie E.; Kjær, Kasper S.; Vankó, György; van Driel, Tim B.; Adachi, Shin-ichi; Bordage, Amélie; Bressler, Christian; Chabera, Pavel; Christensen, Morten; Dohn, Asmus O.; Galler, Andreas; Gawelda, Wojciech; Gosztola, David; Haldrup, Kristoffer; Harlang, Tobias; Liu, Yizhu; Møller, Klaus B.; Németh, Zoltán; Nozawa, Shunsuke; Pápai, Mátyás; Sato, Tokushi; Sato, Takahiro; Suarez-Alcantara, Karina; Togashi, Tadashi; Tono, Kensuke; Uhlig, Jens; Vithanage, Dimali A.; Wärnmark, Kenneth; Yabashi, Makina; Zhang, Jianxin; Sundström, Villy; Nielsen, Martin M.

2015-01-01

Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor–acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances. Experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined. PMID:25727920

Visualizing the non-equilibrium dynamics of photoinduced intramolecular electron transfer with femtosecond X-ray pulses

DOE PAGES

Canton, Sophie E.; Kjær, Kasper S.; Vankó, György; ...

2015-03-02

Ultrafast photoinduced electron transfer preceding energy equilibration still poses many experimental and conceptual challenges to the optimization of photoconversion since an atomic-scale description has so far been beyond reach. Here we combine femtosecond transient optical absorption spectroscopy with ultrafast X-ray emission spectroscopy and diffuse X-ray scattering at the SACLA facility to track the non-equilibrated electronic and structural dynamics within a bimetallic donor–acceptor complex that contains an optically dark centre. Exploiting the 100-fold increase in temporal resolution as compared with storage ring facilities, these measurements constitute the first X-ray-based visualization of a non-equilibrated intramolecular electron transfer process over large interatomic distances.more » Thus experimental and theoretical results establish that mediation through electronically excited molecular states is a key mechanistic feature. The present study demonstrates the extensive potential of femtosecond X-ray techniques as diagnostics of non-adiabatic electron transfer processes in synthetic and biological systems, and some directions for future studies, are outlined.« less

Technical Note: Detective quantum efficiency simulation of a-Se imaging detectors using ARTEMIS.

PubMed

Fang, Yuan; Ito, Takaaki; Nariyuki, Fumito; Kuwabara, Takao; Badano, Aldo; Karim, Karim S

2017-08-01

This work studies the detective quantum efficiency (DQE) of a-Se-based solid state x-ray detectors for medical imaging applications using ARTEMIS, a Monte Carlo simulation tool for modeling x-ray photon, electron and charged carrier transport in semiconductors with the presence of applied electric field. ARTEMIS is used to model the signal formation process in a-Se. The simulation model includes x-ray photon and high-energy electron interactions, and detailed electron-hole pair transport with applied detector bias taking into account drift, diffusion, Coulomb interactions, recombination and trapping. For experimental validation, the DQE performance of prototype a-Se detectors is measured following IEC Testing Standard 62220-1-3. Comparison of simulated and experimental DQE results show reasonable agreement for RQA beam qualities. Experimental validation demonstrated within 5% percentage difference between simulation and experimental DQE results for spatial frequency above 0.25 cycles/mm using uniform applied electric field for RQA beam qualities (RQA5, RQA7 and RQA9). Results include two different prototype detectors with thicknesses of 240 μm and 1 mm. ARTEMIS can be used to model the DQE of a-Se detectors as a function of x-ray energy, detector thickness, and spatial frequency. The ARTEMIS model can be used to improve understanding of the physics of x-ray interactions in a-Se and in optimization studies for the development of novel medical imaging applications. © 2017 American Association of Physicists in Medicine.

Advances in X-ray optics: From metrology characterization to wavefront sensing-based optimization of active optics

DOE PAGES

Cocco, Daniele; Idir, Mourad; Morton, Daniel; ...

2018-03-20

Experiments using high brightness X-rays are on the forefront of science due to the vast variety of knowledge they can provide. New Synchrotron Radiation (SR) and Free Electron Laser (FEL) light sources provide unique tools for advanced studies using X-rays. Top-level scientists from around the world are attracted to these beamlines to perform unprecedented experiments. High brightness, low emittance light sources allow beamline scientists the possibility to dream up cutting-edge experimental stations. X-ray optics play a key role in bringing the beam from the source to the experimental stations. This paper explores the recent developments in X-ray optics. It touchesmore » on simulations, diagnostics, metrology and adaptive optics, giving an overview of the role X-ray optics have played in the recent past. It will also touch on future developments for one of the most active field in the X-ray science.« less

Advances in X-ray optics: From metrology characterization to wavefront sensing-based optimization of active optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cocco, Daniele; Idir, Mourad; Morton, Daniel

Experiments using high brightness X-rays are on the forefront of science due to the vast variety of knowledge they can provide. New Synchrotron Radiation (SR) and Free Electron Laser (FEL) light sources provide unique tools for advanced studies using X-rays. Top-level scientists from around the world are attracted to these beamlines to perform unprecedented experiments. High brightness, low emittance light sources allow beamline scientists the possibility to dream up cutting-edge experimental stations. X-ray optics play a key role in bringing the beam from the source to the experimental stations. This paper explores the recent developments in X-ray optics. It touchesmore » on simulations, diagnostics, metrology and adaptive optics, giving an overview of the role X-ray optics have played in the recent past. It will also touch on future developments for one of the most active field in the X-ray science.« less

Study of Super- and Subsonic Ionization Fronts in Low-Density, Soft X-Ray-Irradiated Foam Targets

NASA Astrophysics Data System (ADS)

Willi, O.; Barringer, L.; Vickers, C.; Hoarty, D.

2000-04-01

The transition from super- to subsonic propagation of an ionization front has been studied in X-ray irradiated, low-density foam targets using soft X-ray imaging and point projection absorption spectroscopy. The foams were doped with chlorine and irradiated with an intense pulse of soft X-ray radiation with a temperature up to 120 eV produced by laser heating a burnthrough converter foil. The cylindrical foam targets were radiographed side-on allowing the change in the chlorine ionization and hence the front to be observed. From the absolute target transmission the density profile was obtained. Comparison of experimental absorption spectra with simulated ones allowed the temperature of the heated material to be inferred for the first time without reliance on detailed hydrodynamic simulations to interpret the data. The experimental observations were compared to radiation hydrodynamic simulations.

Structural studies of homoisoflavonoids: NMR spectroscopy, X-ray diffraction, and theoretical calculations

NASA Astrophysics Data System (ADS)

Sievänen, Elina; Toušek, Jaromír; Lunerová, Kamila; Marek, Jaromír; Jankovská, Dagmar; Dvorská, Margita; Marek, Radek

2010-08-01

In this article we present a detailed structural investigation for five homoisoflavonoids, molecules important from the pharmacological point of view. For studying the electron distribution as well as its influence on the physicochemical properties, NMR spectroscopy, X-ray diffraction, and theoretical calculations have been used. Nuclear magnetic shieldings obtained by using DFT calculations for optimized molecular geometries are correlated with the experimentally determined chemical shifts. The theoretical data are well in agreement with the experimental values. The single crystal X-ray structures of homoisoflavonoid derivatives 1, 3, and 4 have been solved. The molecular geometries and crystal packing determined by X-ray diffraction are used for characterizing the intermolecular interactions. Electron distribution is crucial for the stability of radicals and hence the antioxidant efficiency of flavonoid structures. The hydrogen bonding governs the formation of complexes of homoisoflavonoids with biological targets.

The study of X-ray scattering to determine surface topography of smooth surfaces. [X-ray telescope mirrors

NASA Technical Reports Server (NTRS)

Williams, A. C.

1982-01-01

The scattering of X-rays from state-of-the-art polished mirrors is discussed with reference to the requirements of the Advanced X-ray Astrophysics Facility telescope. An experimental set-up is described which allows information to be obtained with subarcsecond resolution. A sample of the data obtained is presented along with a possible theoretical model for its interpretation.

Electron calibration of a high energy cosmic ray detector

NASA Technical Reports Server (NTRS)

Simnett, G. M.; Silverberg, R. F.; Crannell, C. J.; Gearhart, R. A.; Hagen, F. A.; Jones, W. V.; Kurz, R. J.; Ormes, J. F.; Price, R. D.

1972-01-01

The spectrum of cosmic ray electrons above 10 GeV was studied extensively. The spectrum is predicted to steepen at an energy which is related to the lifetime of electrons in the interstellar medium against losses due to inverse Compton collisions with photons and to synchrotron radiation in galactic magnetic fields. The experimental results diverge widely; the lack of agreement between the various measurements is due to a variety of experimental problems.

High energy astronomy or astrophysics and properties of the interplanetary plasma

NASA Technical Reports Server (NTRS)

1971-01-01

The research activities related to high energy astrophysics and interplanetary plasma are reported. The experimental work in the following areas are described: (1) balloon-and rocket-borne cosmic X-ray, (2) X-ray spectroscopy, and (3) OSO-3 gamma ray experiment. Plasma studies in the interplanetary region, magnetosphere, and geomagnetic tail are included.

X-ray irradiation of soda-lime glasses studied in situ with surface plasmon resonance spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Serrano, A.; Galvez, F.; Rodriguez de la Fuente, O.

2013-03-21

We present here a study of hard X-ray irradiation of soda-lime glasses performed in situ and in real time. For this purpose, we have used a Au thin film grown on glass and studied the excitation of its surface plasmon resonance (SPR) while irradiating the sample with X-rays, using a recently developed experimental setup at a synchrotron beamline [Serrano et al., Rev. Sci. Instrum. 83, 083101 (2012)]. The extreme sensitivity of the SPR to the features of the glass substrate allows probing the modifications caused by the X-rays. Irradiation induces color centers in the soda-lime glass, modifying its refractive index.more » Comparison of the experimental results with simulated data shows that both, the real and the imaginary parts of the refractive index of soda-lime glasses, change upon irradiation in time intervals of a few minutes. After X-ray irradiation, the effects are partially reversible. The defects responsible for these modifications are identified as non-bridging oxygen hole centers, which fade by recombination with electrons after irradiation. The kinetics of the defect formation and fading process are also studied in real time.« less

X-ray attenuation properties of stainless steel (u)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lily L; Berry, Phillip C

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 stainlessmore » 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.« less

First-Principles Predictions of Near-Edge X-ray Absorption Fine Structure Spectra of Semiconducting Polymers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Gregory M.; Patel, Shrayesh N.; Pemmaraju, C. D.

The electronic structure and molecular orientation of semiconducting polymers in thin films determine their ability to transport charge. Methods based on near-edge X-ray absorption fine structure (NEXAFS) spectroscopy can be used to probe both the electronic structure and microstructure of semiconducting polymers in both crystalline and amorphous films. However, it can be challenging to interpret NEXAFS spectra on the basis of experimental data alone, and accurate, predictive calculations are needed to complement experiments. Here, we show that first-principles density functional theory (DFT) can be used to model NEXAFS spectra of semiconducting polymers and to identify the nature of transitions inmore » complicated NEXAFS spectra. Core-level X-ray absorption spectra of a set of semiconducting polymers were calculated using the excited electron and core-hole (XCH) approach based on constrained-occupancy DFT. A comparison of calculations on model oligomers and periodic structures with experimental data revealed the requirements for accurate prediction of NEXAFS spectra of both conjugated homopolymers and donor–acceptor polymers. The NEXAFS spectra predicted by the XCH approach were applied to study molecular orientation in donor–acceptor polymers using experimental spectra and revealed the complexity of using carbon edge spectra in systems with large monomeric units. The XCH approach has sufficient accuracy in predicting experimental NEXAFS spectra of polymers that it should be considered for design and analysis of measurements using soft X-ray techniques, such as resonant soft X-ray scattering and scanning transmission X-ray microscopy.« less

Three-dimensional monochromatic x-ray CT

NASA Astrophysics Data System (ADS)

Saito, Tsuneo; Kudo, Hiroyuki; Takeda, Tohoru; Itai, Yuji; Tokumori, Kenji; Toyofuku, Fukai; Hyodo, Kazuyuki; Ando, Masami; Nishimura, Ktsuyuki; Uyama, Chikao

1995-08-01

In this paper, we describe a 3D computed tomography (3D CT) using monochromatic x-rays generated by synchrotron radiation, which performs a direct reconstruction of 3D volume image of an object from its cone-beam projections. For the develpment of 3D CT, scanning orbit of x-ray source to obtain complete 3D information about an object and corresponding 3D image reconstruction algorithm are considered. Computer simulation studies demonstrate the validities of proposed scanning method and reconstruction algorithm. A prototype experimental system of 3D CT was constructed. Basic phantom examinations and specific material CT image by energy subtraction obtained in this experimental system are shown.

X-ray natural widths, level widths and Coster-Kronig transition probabilities

NASA Astrophysics Data System (ADS)

Papp, T.; Campbell, J. L.; Varga, D.

1997-01-01

A critical review is given for the K-N7 atomic level widths. The experimental level widths were collected from x-ray photoelectron spectroscopy (XPS), x-ray emission spectroscopy (XES), x-ray spectra fluoresced by synchrotron radiation, and photoelectrons from x-ray absorption (PAX). There are only limited atomic number ranges for a few atomic levels where data are available from more than one source. Generally the experimental level widths have large scatter compared to the reported error bars. The experimental data are compared with the recent tabulation of Perkins et al. and of Ohno et al. Ohno et al. performed a many body approach calculation for limited atomic number ranges and have obtained reasonable agreement with the experimental data. Perkins et al. presented a tabulation covering the K-Q1 shells of all atoms, based on extensions of the Scofield calculations for radiative rates and extensions of the Chen calculations for non-radiative rates. The experimental data are in disagreement with this tabulation, in excess of a factor of two in some cases. A short introduction to the experimental Coster-Kronig transition probabilities is presented. It is our opinion that the different experimental approaches result in systematically different experimental data.

Studying the energy dependence of intrinsic conversion efficiency of single crystal scintillators under X-ray excitation

NASA Astrophysics Data System (ADS)

Kalyvas, N.; Valais, I.; David, S.; Michail, Ch.; Fountos, G.; Liaparinos, P.; Kandarakis, I.

2014-05-01

Single crystal scintilators are used in various radiation detectors applications. The efficiency of the crystal can be determined by the Detector Optical Gain (DOG) defined as the ratio of the emitted optical photon flux over the incident radiation photons flux. A parameter affecting DOG is the intrinsic conversion efficiency ( n C ) giving the percentage of the X-ray photon power converted to optical photon power. n C is considered a constant value for X-ray energies in the order of keV although a non-proportional behavior has been reported. In this work an analytical model, has been utilized to single crystals scintillators GSO:Ce, LSO:Ce and LYSO:Ce to examine whether the intrinsic conversion efficiency shows non proportional behavior under X-ray excitation. DOG was theoretically calculated as a function of the incident X-ray spectrum, the X-ray absorption efficiency, the energy of the produced optical photons and the light transmission efficiency. The theoretical DOG values were compared with experimental data obtained by irradiating the crystals with X-rays at tube voltages from 50 to 140 kV and by measuring the light energy flux emitted from the irradiated screen. An initial value for n C (calculated from literature data) was assumed for the X-ray tube voltage of 50 kV. For higher X-ray tube voltages the optical photon propagation phenomena was assumed constant and any deviations between experimental and theoretical data were associated with changes in the intrinsic conversion efficiency. The experimental errors were below 7% for each experimental setup. The behavior of n C values for LSO:Ce and LYSO:Ce were found very similar, i.e., ranging with values from 0.089 at 50 kV to 0.015 at 140 kV, while for GSO:Ce, n C demonstrated a peak at 80 kV.

A United Effort for Crystal Growth, Neutron Scattering, and X-ray Scattering Studies of Novel Correlated Electron Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Young S.

2015-02-12

The research accomplishments during the award involved experimental studies of correlated electron systems and quantum magnetism. The techniques of crystal growth, neutron scattering, x-ray scattering, and thermodynamic & transport measurements were employed, and graduate students and postdoctoral research associates were trained in these techniques.

First experience with x-ray dark-field radiography for human chest imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Noel, Peter B.; Willer, Konstantin; Fingerle, Alexander A.; Gromann, Lukas B.; De Marco, Fabio; Scherer, Kai H.; Herzen, Julia; Achterhold, Klaus; Gleich, Bernhard; Münzel, Daniela; Renz, Martin; Renger, Bernhard C.; Fischer, Florian; Braun, Christian; Auweter, Sigrid; Hellbach, Katharina; Reiser, Maximilian F.; Schröter, Tobias; Mohr, Jürgen; Yaroshenko, Andre; Maack, Hanns-Ingo; Pralow, Thomas; van der Heijden, Hendrik; Proksa, Roland; Köhler, Thomas; Wieberneit, Nataly; Rindt, Karsten; Rummeny, Ernst J.; Pfeiffer, Franz

2017-03-01

Purpose: To evaluate the performance of an experimental X-ray dark-field radiography system for chest imaging in humans and to compare with conventional diagnostic imaging. Materials and Methods: The study was institutional review board (IRB) approved. A single human cadaver (52 years, female, height: 173 cm, weight: 84 kg, chest circumference: 97 cm) was imaged within 24 hours post mortem on the experimental x-ray dark-field system. In addition, the cadaver was imaged on a clinical CT system to obtain a reference scan. The grating-based dark-field radiography setup was equipped with a set of three gratings to enable grating-based dark-field contrast x-ray imaging. The prototype operates at an acceleration voltage of up to 70 kVp and with a field-of-view large enough for clinical chest x-ray (>35 x 35 cm2). Results: It was feasible to extract x-ray dark-field signal of the whole human thorax, clearly demonstrating that human x-ray dark-field chest radiography is feasible. Lung tissue produced strong scattering, reflected in a pronounced x-ray dark-field signal. The ribcage and the backbone are less prominent than the lung but are also distinguishable. Finally, the soft tissue is not present in the dark-field radiography. The regions of the lungs affected by edema, as verified by CT, showed less dark-field signal compared to healthy lung tissue. Conclusion: Our results reveal the current status of translating dark-field imaging from a micro (small animal) scale to a macro (patient) scale. The performance of the experimental x-ray dark-field radiography setup offers, for the first time, obtaining multi-contrast chest x-ray images (attenuation and dark-field signal) from a human cadaver.

High-power laser interaction with low-density C–Cu foams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pérez, F.; Colvin, J. D.; May, M. J.

2015-11-15

We study the propagation of high-power laser beams in micro-structured carbon foams by monitoring the x-ray output from deliberately introduced Cu content. In particular, we characterize this phenomenon measuring absolute time-resolved x-ray yields, time-resolved x-ray imaging, and x-ray spectroscopy. New experimental results for C–Cu foams show a faster heat front velocity than simulation that assumed homogeneous plasma. We suggest the foam micro-structure may explain this trend.

Gamma ray spectroscopy in astrophysics: Solar gamma ray astronomy on solar maximum mission. [experimental design

NASA Technical Reports Server (NTRS)

Forrest, D. J.

1978-01-01

The SMM gamma ray experiment and the important scientific capabilities of the instrument are discussed. The flare size detectable as a function of spectrum integration time was studied. A preliminary estimate indicates that a solar gamma ray line at 4.4 MeV one-fifth the intensity of that believed to have been emitted on 4 August 1972 can be detected in approximately 1000 sec with a confidence level of 99%.

High-power laser interaction with low-density C–Cu foams

DOE PAGES

Pérez, F.; Colvin, J. D.; May, M. J.; ...

2015-11-19

Here, we study the propagation of high-power laser beams in micro-structured carbon foams by monitoring the x-ray output from deliberately introduced Cu content. In particular, we characterize this phenomenon measuring absolute time-resolved x-ray yields, time-resolved x-ray imaging, and x-ray spectroscopy. New experimental results for C–Cu foams show a faster heat front velocity than simulation that assumed homogeneous plasma. We suggest the foam micro-structure may explain this trend.

An Anonymous Referee Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tobin, J. G.

2015-06-08

This is a combined experimental and theoretical study of the compound UO 2, UO 2(NO 3) 2(H 20) 6 and UO 0.75Pu 0.25O 2, using resonant inelastic x-ray scattering (RXIS), high resolution x-ray absorption (XAS) and LDA and LDA-U calculations.

Spatially confined low-power optically pumped ultrafast synchrotron x-ray nanodiffraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Joonkyu; Zhang, Qingteng; Chen, Pice

2015-08-27

The combination of ultrafast optical excitation and time-resolved synchrotron x-ray nanodiffraction provides unique insight into the photoinduced dynamics of materials, with the spatial resolution required to probe individual nanostructures or small volumes within heterogeneous materials. Optically excited x-ray nanobeam experiments are challenging because the high total optical power required for experimentally relevant optical fluences leads to mechanical instability due to heating. For a given fluence, tightly focusing the optical excitation reduces the average optical power by more than three orders of magnitude and thus ensures sufficient thermal stability for x-ray nanobeam studies. Delivering optical pulses via a scannable fiber-coupled opticalmore » objective provides a well-defined excitation geometry during rotation and translation of the sample and allows the selective excitation of isolated areas within the sample. Finally, experimental studies of the photoinduced lattice dynamics of a 35 nm BiFeO 3 thin film on a SrTiO 3 substrate demonstrate the potential to excite and probe nanoscale volumes.« less

Compton scattering study of electron momentum distribution in lithium fluoride using 662 keV gamma radiations

NASA Astrophysics Data System (ADS)

Vijayakumar, R.; Shivaramu; Ramamurthy, N.; Ford, M. J.

2008-12-01

Here we report the first ever 137Cs Compton spectroscopy study of lithium fluoride. The spherical average Compton profiles of lithium fluoride are deduced from Compton scattering measurements on poly crystalline sample at gamma ray energy of 662 keV. To compare the experimental data, we have computed the spherical average Compton profiles using self-consistent Hartree-Fock wave functions employed on linear combination of atomic orbital (HF-LCAO) approximation. The directional Compton profiles and their anisotropic effects are also calculated using the same HF-LCAO approximation. The experimental spherical average profiles are found to be in good agreement with the corresponding HF-LCAO calculations and in qualitative agreement with Hartree-Fock free atom values. The present experimental isotropic and calculated directional profiles are also compared with the available experimental isotropic and directional Compton profiles using 59.54 and 159 keV γ-rays.

Picosecond x-ray diagnostics for third and fourth generation synchrotron sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeCamp, Matthew

2016-03-30

In the DOE-EPSCoR State/National Laboratory partnership grant ``Picosecond x-ray diagnostics for third and fourth generation synchrotron sources'' Dr. DeCamp set forth a partnership between the University of Delaware and Argonne National Laboratory. This proposal aimed to design and implement a series of experiments utilizing, or improving upon, existing time-domain hard x-ray spectroscopies at a third generation synchrotron source. Specifically, the PI put forth three experimental projects to be explored in the grant cycle: 1) implementing a picosecond ``x-ray Bragg switch'' using a laser excited nano-structured metallic film, 2) designing a robust x-ray optical delay stage for x-ray pump-probe studies atmore » a hard x-ray synchrotron source, and 3) building/installing a laser based x-ray source at the Advanced Photon Source for two-color x-ray pump-probe studies.« less

Beam Heating of Samples: Modeling and Verification. Part 2

NASA Technical Reports Server (NTRS)

Kazmierczak, Michael; Gopalakrishnan, Pradeep; Kumar, Raghav; Banerjee Rupak; Snell, Edward; Bellamy, Henry; Rosenbaum, Gerd; vanderWoerd, Mark

2006-01-01

Energy absorbed from the X-ray beam by the sample requires cooling by forced convection (i.e. cryostream) to minimize temperature increase and the damage caused to the sample by the X-ray heating. In this presentation we will first review the current theoretical models and recent studies in the literature, which predict the sample temperature rise for a given set of beam parameters. It should be noted that a common weakness of these previous studies is that none of them provide actual experimental confirmation. This situation is now remedied in our investigation where the problem of x-ray sample heating is taken up once more. We have theoretically investigated, and at the same time, in addition to the numerical computations, performed experiments to validate the predictions. We have modeled, analyzed and experimentally tested the temperature rise of a 1 mm diameter glass sphere (sample surrogate) exposed to an intense synchrotron X-ray beam, while it is being cooled in a uniform flow of nitrogen gas. The heat transfer, including external convection and internal heat conduction was theoretically modeled using CFD to predict the temperature variation in the sphere during cooling and while it was subjected to an undulator (ID sector 19) X-ray beam at the APS. The surface temperature of the sphere during the X-ray beam heating was measured using the infrared camera measurement technique described in a previous talk. The temperatures from the numerical predictions and experimental measurements are compared and discussed. Additional results are reported for the two different sphere sizes and for two different supporting pin orientations.

[Study on spectrum analysis of X-ray based on rotational mass effect in special relativity].

PubMed

Yu, Zhi-Qiang; Xie, Quan; Xiao, Qing-Quan

2010-04-01

Based on special relativity, the formation mechanism of characteristic X-ray has been studied, and the influence of rotational mass effect on X-ray spectrum has been given. A calculation formula of the X-ray wavelength based upon special relativity was derived. Error analysis was carried out systematically for the calculation values of characteristic wavelength, and the rules of relative error were obtained. It is shown that the values of the calculation are very close to the experimental values, and the effect of rotational mass effect on the characteristic wavelength becomes more evident as the atomic number increases. The result of the study has some reference meaning for the spectrum analysis of characteristic X-ray in application.

Radiographic applications of spatial frequency multiplexing

NASA Technical Reports Server (NTRS)

Macovski, A.

1981-01-01

The application of spacial frequency encoding techniques which allow different regions of the X-ray spectrum to be encoded on conventional radiographs was studied. Clinical considerations were reviewed, as were experimental studies involving the encoding and decoding of X-ray images at different energies and the subsequent processing of the data to produce images of specific materials in the body.

Geometry-constraint-scan imaging for in-line phase contrast micro-CT.

PubMed

Fu, Jian; Yu, Guangyuan; Fan, Dekai

2014-01-01

X-ray phase contrast computed tomography (CT) uses the phase shift that x-rays undergo when passing through matter, rather than their attenuation, as the imaging signal and may provide better image quality in soft-tissue and biomedical materials with low atomic number. Here a geometry-constraint-scan imaging technique for in-line phase contrast micro-CT is reported. It consists of two circular-trajectory scans with x-ray detector at different positions, the phase projection extraction method with the Fresnel free-propagation theory and the filter back-projection reconstruction algorithm. This method removes the contact-detector scan and the pure phase object assumption in classical in-line phase contrast Micro-CT. Consequently it relaxes the experimental conditions and improves the image contrast. This work comprises a numerical study of this technique and its experimental verification using a biomedical composite dataset measured at an x-ray tube source Micro-CT setup. The numerical and experimental results demonstrate the validity of the presented method. It will be of interest for a wide range of in-line phase contrast Micro-CT applications in biology and medicine.

Thick-target-method study of Mα β x-ray production cross sections of Pb and Bi impacted by positrons up to 9 keV

NASA Astrophysics Data System (ADS)

Wu, Y.; Liang, Y.; Xu, M. X.; Yuan, Y.; Chang, C. H.; Qian, Z. C.; Wang, B. Y.; Kuang, P.; Zhang, P.

2018-03-01

Atomic M -shell x-ray production cross sections induced by positrons near the threshold energy have been presented in this paper. In the experiment, online monitoring technology, which utilizes a high-purity germanium detector to record the annihilation photons emitted from the pure thick target impacted by positrons, was developed to obtain the accurate number of the incident positrons. The effects of the multiple scattering of incident positrons, from the bremsstrahlung and annihilation photons and other secondary particles on the experimental characteristic x-ray yield, were eliminated by Monte Carlo simulation in combination with theoretical integral calculation. The Tikhonov regularization method was adopted to handle the ill-posed inverse problem involved in the thick-target method, i.e., x-ray production cross sections by the corrected characteristic x-ray yield. Experimental results of Mα β x-ray production cross sections for Pb and Bi impacted by 6-9-keV positrons were compared with the corresponding values predicted by the distorted-wave Born approximation (DWBA). Good agreement was found between the two. Moreover, we have presented the experimental results on the ratios of the Mα β x-ray production cross sections by electron impact in the literature to that by 6-9-keV positron impact in this work. They were also in accordance with the theoretical ratios calculated by the predictions of DWBA theory.

X-ray free-electron laser studies of dense plasmas

NASA Astrophysics Data System (ADS)

Vinko, Sam M.

2015-10-01

> The high peak brightness of X-ray free-electron lasers (FELs), coupled with X-ray optics enabling the focusing of pulses down to sub-micron spot sizes, provides an attractive route to generating high energy-density systems on femtosecond time scales, via the isochoric heating of solid samples. Once created, the fundamental properties of these plasmas can be studied with unprecedented accuracy and control, providing essential experimental data needed to test and benchmark commonly used theoretical models and assumptions in the study of matter in extreme conditions, as well as to develop new predictive capabilities. Current advances in isochoric heating and spectroscopic plasma studies on X-ray FELs are reviewed and future research directions and opportunities discussed.

The feasibility study on 3-dimensional fluorescent x-ray computed tomography using the pinhole effect for biomedical applications.

PubMed

Sunaguchi, Naoki; Yuasa, Tetsuya; Hyodo, Kazuyuki; Zeniya, Tsutomu

2013-01-01

We propose a 3-dimensional fluorescent x-ray computed tomography (CT) pinhole collimator, aimed at providing molecular imaging with quantifiable measures and sub-millimeter spatial resolution. In this study, we demonstrate the feasibility of this concept and investigate imaging properties such as spatial resolution, contrast resolution and quantifiable measures, by imaging physical phantoms using a preliminary imaging system developed with monochromatic synchrotron x rays constructed at the BLNE-7A experimental line at KEK, Japan.

Recent developments of x-ray lithography in Canada

NASA Astrophysics Data System (ADS)

Chaker, Mohamed; Boily, Stephane; Ginovker, A.; Jean, Alain; Kieffer, Jean-Claude; Mercier, P. P.; Pepin, Henri; Leung, Pak; Currie, John F.; Lafontaine, Hugues

1991-08-01

An overview of current activities in Canada is reported, including x-ray lithography studies based on laser plasma sources and x-ray mask development. In particular, the application of laser plasma sources for x-ray lithography is discussed, taking into account the industrial requirement and the present state of laser technology. The authors describe the development of silicon carbide membranes for x-ray lithography application. SiC films were prepared using either a 100 kHz plasma-enhanced chemical vapor deposition (PECVD) system or a laser ablation technique. These membranes have a relatively large diameter (> 1 in.) and a high optical transparency (> 50%). Experimental studies on stresses in tungsten films deposited with triode sputtering are reported.

Structure of dimethylphenyl betaine hydrochloride studied by X-ray diffraction, DFT calculation, NMR and FTIR spectra

NASA Astrophysics Data System (ADS)

Szafran, M.; Katrusiak, A.; Dega-Szafran, Z.; Kowalczyk, I.

2013-01-01

The structure of dimethylphenyl betaine hydrochloride (1) has been studied by X-ray diffraction, DFT calculations, NMR and FTIR spectra. The crystals are monoclinic, space group P21/c. In the crystal, the Cl- anion is connected with protonated betaine through the O-H⋯Cl- hydrogen bond of 2.943(2) Å. The structures in the gas phase (2) and water solution (3) have been optimized by the B3LYP/6-311++G(d,p) approach and the geometrical results have been compared with the X-ray data of 1. The FTIR spectrum of the solid compound is consistent with the X-ray results. The probable assignments of the anharmonic experimental vibrational frequencies of the investigated chloride (1) based on the calculated harmonic frequencies in water solution (3) are proposed. The correlations between the experimental 1H and 13C NMR chemical shifts (δexp) of 1 in D2O and the magnetic isotropic shielding constants (σcalc) calculated by the GIAO/B3LYP/6-311G++(d,p) approach, using the screening solvation model (COSMO), δexp = a + b σcalc, for optimized molecule 3 in water solution are linear and correctly reproduce the experimental chemical shifts.

Experimental study of burnout in channels with twisted fuel rods

NASA Astrophysics Data System (ADS)

Bol'Shakov, V. V.; Bashkirtsev, S. M.; Kobzar', L. L.; Morozov, A. G.

2007-05-01

The results of experimental studies of pressure drop and critical heat flux in the models of fuel assemblies (FAs) with fuel rod simulators twisted relative to the longitudinal axis and a three-ray cross section are considered. The experimental data are compared to the results obtained with the use of techniques adopted for design calculations with fuel rod bundles of type-VVER reactors.

The effect of exit beam phase aberrations on parallel beam coherent x-ray reconstructions

NASA Astrophysics Data System (ADS)

Hruszkewycz, S. O.; Harder, R.; Xiao, X.; Fuoss, P. H.

2010-12-01

Diffraction artifacts from imperfect x-ray windows near the sample are an important consideration in the design of coherent x-ray diffraction measurements. In this study, we used simulated and experimental diffraction patterns in two and three dimensions to explore the effect of phase imperfections in a beryllium window (such as a void or inclusion) on the convergence behavior of phasing algorithms and on the ultimate reconstruction. A predictive relationship between beam wavelength, sample size, and window position was derived to explain the dependence of reconstruction quality on beryllium defect size. Defects corresponding to this prediction cause the most damage to the sample exit wave and induce signature error oscillations during phasing that can be used as a fingerprint of experimental x-ray window artifacts. The relationship between x-ray window imperfection size and coherent x-ray diffractive imaging reconstruction quality explored in this work can play an important role in designing high-resolution in situ coherent imaging instrumentation and will help interpret the phasing behavior of coherent diffraction measured in these in situ environments.

The effect of exit beam phase aberrations on parallel beam coherent x-ray reconstructions.

PubMed

Hruszkewycz, S O; Harder, R; Xiao, X; Fuoss, P H

2010-12-01

Diffraction artifacts from imperfect x-ray windows near the sample are an important consideration in the design of coherent x-ray diffraction measurements. In this study, we used simulated and experimental diffraction patterns in two and three dimensions to explore the effect of phase imperfections in a beryllium window (such as a void or inclusion) on the convergence behavior of phasing algorithms and on the ultimate reconstruction. A predictive relationship between beam wavelength, sample size, and window position was derived to explain the dependence of reconstruction quality on beryllium defect size. Defects corresponding to this prediction cause the most damage to the sample exit wave and induce signature error oscillations during phasing that can be used as a fingerprint of experimental x-ray window artifacts. The relationship between x-ray window imperfection size and coherent x-ray diffractive imaging reconstruction quality explored in this work can play an important role in designing high-resolution in situ coherent imaging instrumentation and will help interpret the phasing behavior of coherent diffraction measured in these in situ environments.

Delayed Gamma-ray Spectroscopy for Safeguards Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mozin, Vladimir

The delayed gamma-ray assay technique utilizes an external neutron source (D-D, D-T, or electron accelerator-driven), and high-resolution gamma-ray spectrometers to perform characterization of SNM materials behind shielding and in complex configurations such as a nuclear fuel assembly. High-energy delayed gamma-rays (2.5 MeV and above) observed following the active interrogation, provide a signature for identification of specific fissionable isotopes in a mixed sample, and determine their relative content. Potential safeguards applications of this method are: 1) characterization of fresh and spent nuclear fuel assemblies in wet or dry storage; 2) analysis of uranium enrichment in shielded or non-characterized containers or inmore » the presence of a strong radioactive background and plutonium contamination; 3) characterization of bulk and waste and product streams at SNM processing plants. Extended applications can include warhead confirmation and warhead dismantlement confirmation in the arms control area, as well as SNM diagnostics for the emergency response needs. In FY16 and prior years, the project has demonstrated the delayed gamma-ray measurement technique as a robust SNM assay concept. A series of empirical and modeling studies were conducted to characterize its response sensitivity, develop analysis methodologies, and analyze applications. Extensive experimental tests involving weapons-grade Pu, HEU and depleted uranium samples were completed at the Idaho Accelerator Center and LLNL Dome facilities for various interrogation time regimes and effects of the neutron source parameters. A dedicated delayed gamma-ray response modeling technique was developed and its elements were benchmarked in representative experimental studies, including highresolution gamma-ray measurements of spent fuel at the CLAB facility in Sweden. The objective of the R&D effort in FY17 is to experimentally demonstrate the feasibility of the delayed gamma-ray interrogation of shielded SNM samples with portable neutron sources suitable for field applications.« less

The effect of laser radiation on the diffraction of X-rays in crystals

NASA Astrophysics Data System (ADS)

Trushin, V. N.; Chuprunov, E. V.; Khokhlov, A. F.

1988-10-01

The effect of laser radiation on the intensity of the X-ray diffraction peaks of KDP, ADP, and CuSO4-5H2O crystals was studied experimentally. This intensity was found to increase as a function of the laser beam power. This result suggests that it is possible to use laser beams to control X-ray intensity in the crystals considered.

Imaging performance of a hybrid x-ray computed tomography-fluorescence molecular tomography system using priors.

PubMed

Ale, Angelique; Schulz, Ralf B; Sarantopoulos, Athanasios; Ntziachristos, Vasilis

2010-05-01

The performance is studied of two newly introduced and previously suggested methods that incorporate priors into inversion schemes associated with data from a recently developed hybrid x-ray computed tomography and fluorescence molecular tomography system, the latter based on CCD camera photon detection. The unique data set studied attains accurately registered data of high spatially sampled photon fields propagating through tissue along 360 degrees projections. Approaches that incorporate structural prior information were included in the inverse problem by adding a penalty term to the minimization function utilized for image reconstructions. Results were compared as to their performance with simulated and experimental data from a lung inflammation animal model and against the inversions achieved when not using priors. The importance of using priors over stand-alone inversions is also showcased with high spatial sampling simulated and experimental data. The approach of optimal performance in resolving fluorescent biodistribution in small animals is also discussed. Inclusion of prior information from x-ray CT data in the reconstruction of the fluorescence biodistribution leads to improved agreement between the reconstruction and validation images for both simulated and experimental data.

Chemical bonding in aqueous hexacyano cobaltate from photon- and electron-detection perspectives

PubMed Central

Lalithambika, Sreeju Sreekantan Nair; Atak, Kaan; Seidel, Robert; Neubauer, Antje; Brandenburg, Tim; Xiao, Jie; Winter, Bernd; Aziz, Emad F.

2017-01-01

The electronic structure of the [Co(CN)6]3− complex dissolved in water is studied using X-ray spectroscopy techniques. By combining electron and photon detection methods from the solutions ionized or excited by soft X-rays we experimentally identify chemical bonding between the metal center and the CN ligand. Non-resonant photoelectron spectroscopy provides solute electron binding energies, and nitrogen 1 s and cobalt 2p resonant core-level photoelectron spectroscopy identifies overlap between metal and ligand orbitals. By probing resonances we are able to qualitatively determine the ligand versus metal character of the respective occupied and non-occupied orbitals, purely by experiment. For the same excitations we also detect the emitted X-rays, yielding the complementary resonant inelastic X-ray scattering spectra. For a quantitative interpretation of the spectra, we perform theoretical electronic-structure calculations. The latter provide both orbital energies and orbital character which are found to be in good agreement with experimental energies and with experimentally inferred orbital mixing. We also report calculated X-ray absorption spectra, which in conjunction with our orbital-structure analysis, enables us to quantify various bonding interactions with a particular focus on the water-solvent – ligand interaction and the strength of π-backbonding between metal and ligand. PMID:28098216

Modal Frequency Detection in Composite Beams Using Fiber Optic Sensors

DTIC Science & Technology

1997-04-18

Structures 4, 270-280 (1995). [35] Chen-Jung Li and Ray Asok , "Neural Network Representation of Fatigue Damage Dynamics," Smart Materials and Structures 3...37] Roland Ray Kilcher, "Modal Analysis and Impact Damage Assessment of Composite Laminates: an Experimental Study," M.S. thesis, University of

Apollo-Soyuz pamphlet no. 2: X-rays, gamma-rays. [experimental design

NASA Technical Reports Server (NTRS)

Page, L. W.; From, T. P.

1977-01-01

The nature of high energy radiation and its penetration through earth's atmosphere is examined with emphasis on X-rays, gamma rays, and cosmic radiation and the instruments used in their detection. The history of radio astronomy and the capabilities of the Uhuru satellite are summarized. The ASTP soft X-ray experiment (MA-048) designed to study the spectra in the range from 0.1 to 10 keV and survey the background over a large section of the sky is described, as well as the determination of SMC C-1 as an X-ray pulsar. The crystal activation experiment (MA-151) used to measure the radioactive isotopes created by cosmic rays in crystals used for gamma ray detectors is also discussed.

1-Amino-4-hydroxy-9,10-anthraquinone - An analogue of anthracycline anticancer drugs, interacts with DNA and induces apoptosis in human MDA-MB-231 breast adinocarcinoma cells: Evaluation of structure-activity relationship using computational, spectroscopic and biochemical studies.

PubMed

Mondal, Palash; Roy, Sanjay; Loganathan, Gayathri; Mandal, Bitapi; Dharumadurai, Dhanasekaran; Akbarsha, Mohammad A; Sengupta, Partha Sarathi; Chattopadhyay, Shouvik; Guin, Partha Sarathi

2015-12-01

The X-ray diffraction and spectroscopic properties of 1-amino-4-hydroxy-9,10-anthraquinone (1-AHAQ), a simple analogue of anthracycline chemotherapeutic drugs were studied by adopting experimental and computational methods. The optimized geometrical parameters obtained from computational methods were compared with the results of X-ray diffraction analysis and the two were found to be in reasonably good agreement. X-ray diffraction study, Density Functional Theory (DFT) and natural bond orbital (NBO) analysis indicated two types of hydrogen bonds in the molecule. The IR spectra of 1-AHAQ were studied by Vibrational Energy Distribution Analysis (VEDA) using potential energy distribution (PED) analysis. The electronic spectra were studied by TDDFT computation and compared with the experimental results. Experimental and theoretical results corroborated each other to a fair extent. To understand the biological efficacy of 1-AHAQ, it was allowed to interact with calf thymus DNA and human breast adino-carcinoma cell MDA-MB-231. It was found that the molecule induces apoptosis in this adinocarcinoma cell, with little, if any, cytotoxic effect in HBL-100 normal breast epithelial cell.

Design and study of the characteristics of a three electrode experimental ionization chamber for gamma ray dosimetry of spent fuel

NASA Astrophysics Data System (ADS)

Ahmad, N.; Mirza, Nasir M.; Mirza, Sikander M.; Rashid, T.; Tufail, M.; Khan, Liaquat A.

1992-09-01

The ( I, V) characteristics of two and three electrode ionization chamber filled with argon gas have been studied. To determine the sensitivity and the response with increase in exposure rate, the chamber was tested with a 60Co commercial irradiator. The response is linear up to more than 1.5 krad/h. The experimentally measured sensitivity of the chamber is 1.849×10 -13 A/cm 3 per rad/h when the argon gas pressure in the chamber is 1.24 GPa (180 psi). The effect of transparency of the intermediate electrod on the saturation current due to 137Cs gamma-rays has also been studied. The experimental results show that the electrode with holes of small diameter acts as a better intermediate electrode as compared to the electrodes without holes or with holes of a larger diameter. The chamber has also been teste with fission product gamma-rays from spent fuel elements of a typical pool type research reactor. The results indicate that the presence of an intermediate electrode lowers the operating voltage by 50% and reduces the slope in the plateau region.

Multi-scale mechanics of granular solids from grain-resolved X-ray measurements

NASA Astrophysics Data System (ADS)

Hurley, R. C.; Hall, S. A.; Wright, J. P.

2017-11-01

This work discusses an experimental technique for studying the mechanics of three-dimensional (3D) granular solids. The approach combines 3D X-ray diffraction and X-ray computed tomography to measure grain-resolved strains, kinematics and contact fabric in the bulk of a granular solid, from which continuum strains, grain stresses, interparticle forces and coarse-grained elasto-plastic moduli can be determined. We demonstrate the experimental approach and analysis of selected results on a sample of 1099 stiff, frictional grains undergoing multiple uniaxial compression cycles. We investigate the inter-particle force network, elasto-plastic moduli and associated length scales, reversibility of mechanical responses during cyclic loading, the statistics of microscopic responses and microstructure-property relationships. This work serves to highlight both the fundamental insight into granular mechanics that is furnished by combined X-ray measurements and describes future directions in the field of granular materials that can be pursued with such approaches.

Monte Carlo simulation of Ray-Scan 64 PET system and performance evaluation using GATE toolkit

NASA Astrophysics Data System (ADS)

Li, Suying; Zhang, Qiushi; Vuletic, Ivan; Xie, Zhaoheng; Yang, Kun; Ren, Qiushi

2017-02-01

In this study, we aimed to develop a GATE model for the simulation of Ray-Scan 64 PET scanner and model its performance characteristics. A detailed implementation of system geometry and physical process were included in the simulation model. Then we modeled the performance characteristics of Ray-Scan 64 PET system for the first time, based on National Electrical Manufacturers Association (NEMA) NU-2 2007 protocols and validated the model against experimental measurement, including spatial resolution, sensitivity, counting rates and noise equivalent count rate (NECR). Moreover, an accurate dead time module was investigated to simulate the counting rate performance. Overall results showed reasonable agreement between simulation and experimental data. The validation results showed the reliability and feasibility of the GATE model to evaluate major performance of Ray-Scan 64 PET system. It provided a useful tool for a wide range of research applications.

Gamma-Ray Astrophysics: New Insight Into the Universe

NASA Technical Reports Server (NTRS)

Fichtel, Carl E.; Trombka, Jacob I.

1997-01-01

During the 15 years that have passed since the first edition of this book was published, there has been a major increase in our knowledge of gamma-ray astronomy. Much of this advance arises from the extensive results that have been forthcoming from the Compton Gamma-Ray Observatory. There has been the discovery of a new class of gamma-ray objects, namely high-energy gamma- ray-emitting blazars, a special class of Active Galactic Nuclei, whose basic high-energy properties now seem to be understood. A much improved picture of our galaxy now exists in the frequency range of gamma rays. The question of whether cosmic rays are galactic or metagalactic now seems settled with certainty. Significant new information exists on the gamma-ray properties of neutron star pulsars, Seyfert galaxies, and gamma-ray bursts. Substantial new insight has been obtained on solar phenomena through gamma-ray observations. Hence, this seemed to be an appropriate time to write a new edition of this book to add the important scientific implications of these many new findings. The special importance of gamma-ray astrophysics had long been recognized by many physicists and astronomers, and theorists had pursued many aspects of the subject well before the experimental results began to become available. The slower development of the experimental side was not because of a lack of incentive, but due to the substantial experimental difficulties that had to be overcome. Thus, as the gamma-ray results became available in much greater number and detail, it was possible to build upon the theoretical work that already existed and to make substantial progress in the study of many of the phenomena involved. Consequently, a much better understanding of many of the astrophysical phenomena mentioned here and others is now possible. Our principal aims in writing this book are the same as they were for the first edition: to provide a text which describes the significance of gamma-ray astrophysics and to assemble in one place a treatment of gamma rays emitted from bodies in the solar i system, from objects in our galaxy, as well as from interactions between cosmic rays and the interstellar medium, and from beyond our galaxy. Thus, this book is intended for those in astrophysics who wish to have the opportunity to learn more about the evolving field of gamma-ray astronomy and its relationship to the high-energy, evolutionary processes occurring in the universe. The last three chapters of the book provide a general discussion of the experimental aspects of the field that seemed best treated together, separately from the astrophysical aspects of gamma-ray astronomy that are discussed in the first ten chapters.

High-energy synchrotron x-ray techniques for studying irradiated materials

DOE PAGES

Park, Jun-Sang; Zhang, Xuan; Sharma, Hemant; ...

2015-03-20

High performance materials that can withstand radiation, heat, multiaxial stresses, and corrosive environment are necessary for the deployment of advanced nuclear energy systems. Nondestructive in situ experimental techniques utilizing high energy x-rays from synchrotron sources can be an attractive set of tools for engineers and scientists to investigate the structure–processing–property relationship systematically at smaller length scales and help build better material models. In this paper, two unique and interconnected experimental techniques, namely, simultaneous small-angle/wide-angle x-ray scattering (SAXS/WAXS) and far-field high-energy diffraction microscopy (FF-HEDM) are presented. Finally, the changes in material state as Fe-based alloys are heated to high temperatures ormore » subject to irradiation are examined using these techniques.« less

Calculated X-ray Intensities Using Monte Carlo Algorithms: A Comparison to Experimental EPMA Data

NASA Technical Reports Server (NTRS)

Carpenter, P. K.

2005-01-01

Monte Carlo (MC) modeling has been used extensively to simulate electron scattering and x-ray emission from complex geometries. Here are presented comparisons between MC results and experimental electron-probe microanalysis (EPMA) measurements as well as phi(rhoz) correction algorithms. Experimental EPMA measurements made on NIST SRM 481 (AgAu) and 482 (CuAu) alloys, at a range of accelerating potential and instrument take-off angles, represent a formal microanalysis data set that has been widely used to develop phi(rhoz) correction algorithms. X-ray intensity data produced by MC simulations represents an independent test of both experimental and phi(rhoz) correction algorithms. The alpha-factor method has previously been used to evaluate systematic errors in the analysis of semiconductor and silicate minerals, and is used here to compare the accuracy of experimental and MC-calculated x-ray data. X-ray intensities calculated by MC are used to generate a-factors using the certificated compositions in the CuAu binary relative to pure Cu and Au standards. MC simulations are obtained using the NIST, WinCasino, and WinXray algorithms; derived x-ray intensities have a built-in atomic number correction, and are further corrected for absorption and characteristic fluorescence using the PAP phi(rhoz) correction algorithm. The Penelope code additionally simulates both characteristic and continuum x-ray fluorescence and thus requires no further correction for use in calculating alpha-factors.

Synthesis, crystal structures and spectroscopic properties of triazine-based hydrazone derivatives; a comparative experimental-theoretical study.

PubMed

Arshad, Muhammad Nadeem; Bibi, Aisha; Mahmood, Tariq; Asiri, Abdullah M; Ayub, Khurshid

2015-04-03

We report here a comparative theoretical and experimental study of four triazine-based hydrazone derivatives. The hydrazones are synthesized by a three step process from commercially available benzil and thiosemicarbazide. The structures of all compounds were determined by using the UV-Vis., FT-IR, NMR (1H and 13C) spectroscopic techniques and finally confirmed unequivocally by single crystal X-ray diffraction analysis. Experimental geometric parameters and spectroscopic properties of the triazine based hydrazones are compared with those obtained from density functional theory (DFT) studies. The model developed here comprises of geometry optimization at B3LYP/6-31G (d, p) level of DFT. Optimized geometric parameters of all four compounds showed excellent correlations with the results obtained from X-ray diffraction studies. The vibrational spectra show nice correlations with the experimental IR spectra. Moreover, the simulated absorption spectra also agree well with experimental results (within 10-20 nm). The molecular electrostatic potential (MEP) mapped over the entire stabilized geometries of the compounds indicated their chemical reactivates. Furthermore, frontier molecular orbital (electronic properties) and first hyperpolarizability (nonlinear optical response) were also computed at the B3LYP/6-31G (d, p) level of theory.

A software platform for phase contrast x-ray breast imaging research.

PubMed

Bliznakova, K; Russo, P; Mettivier, G; Requardt, H; Popov, P; Bravin, A; Buliev, I

2015-06-01

To present and validate a computer-based simulation platform dedicated for phase contrast x-ray breast imaging research. The software platform, developed at the Technical University of Varna on the basis of a previously validated x-ray imaging software simulator, comprises modules for object creation and for x-ray image formation. These modules were updated to take into account the refractive index for phase contrast imaging as well as implementation of the Fresnel-Kirchhoff diffraction theory of the propagating x-ray waves. Projection images are generated in an in-line acquisition geometry. To test and validate the platform, several phantoms differing in their complexity were constructed and imaged at 25 keV and 60 keV at the beamline ID17 of the European Synchrotron Radiation Facility. The software platform was used to design computational phantoms that mimic those used in the experimental study and to generate x-ray images in absorption and phase contrast modes. The visual and quantitative results of the validation process showed an overall good correlation between simulated and experimental images and show the potential of this platform for research in phase contrast x-ray imaging of the breast. The application of the platform is demonstrated in a feasibility study for phase contrast images of complex inhomogeneous and anthropomorphic breast phantoms, compared to x-ray images generated in absorption mode. The improved visibility of mammographic structures suggests further investigation and optimisation of phase contrast x-ray breast imaging, especially when abnormalities are present. The software platform can be exploited also for educational purposes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Correction factors for the NMi free-air ionization chamber for medium-energy x-rays calculated with the Monte Carlo method.

PubMed

Grimbergen, T W; van Dijk, E; de Vries, W

1998-11-01

A new method is described for the determination of x-ray quality dependent correction factors for free-air ionization chambers. The method is based on weighting correction factors for mono-energetic photons, which are calculated using the Monte Carlo method, with measured air kerma spectra. With this method, correction factors for electron loss, scatter inside the chamber and transmission through the diaphragm and front wall have been calculated for the NMi free-air chamber for medium-energy x-rays for a wide range of x-ray qualities in use at NMi. The newly obtained correction factors were compared with the values in use at present, which are based on interpolation of experimental data for a specific set of x-ray qualities. For x-ray qualities which are similar to this specific set, the agreement between the correction factors determined with the new method and those based on the experimental data is better than 0.1%, except for heavily filtered x-rays generated at 250 kV. For x-ray qualities dissimilar to the specific set, differences up to 0.4% exist, which can be explained by uncertainties in the interpolation procedure of the experimental data. Since the new method does not depend on experimental data for a specific set of x-ray qualities, the new method allows for a more flexible use of the free-air chamber as a primary standard for air kerma for any x-ray quality in the medium-energy x-ray range.

A three-dimensional study of 30- to 300-MeV atmospheric gamma rays

NASA Technical Reports Server (NTRS)

Thompson, D. J.

1974-01-01

A three-dimensional study of atmospheric gamma rays with energy greater than 30 MeV has been carried out. A knowledge of these atmospheric secondaries has significant applications to the study of cosmic gamma rays. For detectors carried on balloons, atmospherically produced gamma rays are the major source of background. For satellite detectors, atmospheric secondaries provide a calibration source. Experimental results were obtained from four balloon flights from Palestine, Texas, with a 15 cm by 15 cm digitized wire grid spark chamber. The energy spectrum for downward-moving gamma rays steepens with increasing atmospheric depth. Near the top of the atmosphere, the spectrum steepens with increasing zenith angle. A new model of atmospheric secondary production has calculated the depth, the energy, and the zenith angle dependence of gamma rays above 30 MeV, using a comprehensive three-dimensional Monte Carlo model of the nucleon-meson-electromagnetic cascade.

[Effects of heat therapy using a far infrared rays heating element for dysmenorrhea in high school girls].

PubMed

Hong, Yeon Ran

2011-02-01

The purpose of this study was designed to identify the effects of heat therapy on dysmenorrhea, heat being provided using a far infrared rays heating element. The research design for the study was a non-equivalent control group quasi-experimental design. Participants were 22 students for the experimental group, and 26 students for the control group. Data were analyzed using SAS WIN 9.1 program. The experimental group had significantly lower mean scores for menstrual pain, dysmenorrhea, and blood pressure than those in the control group. However, no significant differences were found between two groups for pulse, respiration, and temperature. These findings show that thermotherapy was effective for reduction of menstrual pain, dysmenorrhea, and B/P. Therefore, this therapy could be used as a nursing intervention for students with dysmenorrhea.

Future prospects of nuclear reactions induced by gamma-ray beams at ELI-NP

NASA Astrophysics Data System (ADS)

Filipescu, D.; Balabanski, D. L.; Camera, F.; Gheorghe, I.; Ghita, D.; Glodariu, T.; Kaur, J.; Ur, C. A.; Utsunomiya, H.; Varlamov, V. V.

2017-01-01

The future prospects of photonuclear reactions studies at the new Extreme Light Infrastructure—Nuclear Physics (ELI-NP) facility are discussed in view of the pursuit of investigating the electromagnetic response of nuclei using γ-ray beams of unprecedented energy resolution and intensity characteristics. We present here the features of the γ-ray beam source, the emerging ELI-NP experimental program involving photonuclear reactions cross section measurements and spectroscopy and angular measurements of γ-rays and neutrons along with the detection arrays currently under implementation.

Conferences, workshops, trainings

Science.gov Websites

of pulsars and other gamma-rays sources; ii) experimental data from the HAWC and other cosmic rays Advancements in immunology can be made through the development of theoretical and experimental techniques

Effect of antimony-oxide on the shielding properties of some sodium-boro-silicate glasses.

PubMed

Zoulfakar, A M; Abdel-Ghany, A M; Abou-Elnasr, T Z; Mostafa, A G; Salem, S M; El-Bahnaswy, H H

2017-09-01

Some sodium-silicate-boro-antimonate glasses having the molecular composition [(20) Na 2 O - (20) SiO 2 - (60-x) B 2 O 3 - (x) Sb 2 O 3 (where x takes the values 0, 5 … or 20)] have been prepared by the melt quenching method. The melting and annealing temperatures were 1500 and 650K respectively. The amorphous nature of the prepared samples was confirmed by using X-ray diffraction analysis. Both the experimental and empirical density and molar volume values showed gradual increase with increasing Sb 2 O 3 content. The empirical densities showed higher values than those obtained experimentally, while the empirical molar volume values appeared lower than those obtained experimentally, which confirm the amorphous nature and randomness character of the studied samples. The experimentally obtained shielding parameters were approximately coincident with those obtained theoretically by applying WinXCom program. At low gamma-ray energies (0.356 and 0.662MeV) Sb 2 O 3 has approximately no effect on the total Mass Attenuation Coefficient, while at high energies it acts to increase the total Mass Attenuation Coefficient gradually. The obtained Half Value Layer and Mean Free Path values showed gradual decrease as Sb 2 O 3 was gradually increased. Also, the Total Mass Attenuation Coefficient values obtained between about 0.8 and 3.0MeV gamma-ray energy showed a slight decrease, as gamma-ray photon energy increased. This may be due to the differences between the Attenuation Coefficients of both antimony and boron oxides at various gamma-ray photon energies. However, it can be stated that the addition of Sb 2 O 3 into sodium-boro-silicate glasses increases the gamma-ray Attenuation Coefficient and the best sample is that contains 20 mol% of Sb 2 O 3 , which is operating well at 0.356 and 0.662MeV gamma-ray. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simulation of a complete X-ray digital radiographic system for industrial applications.

PubMed

Nazemi, E; Rokrok, B; Movafeghi, A; Choopan Dastjerdi, M H

2018-05-19

Simulating X-ray images is of great importance in industry and medicine. Using such simulation permits us to optimize parameters which affect image's quality without the limitations of an experimental procedure. This study revolves around a novel methodology to simulate a complete industrial X-ray digital radiographic system composed of an X-ray tube and a computed radiography (CR) image plate using Monte Carlo N Particle eXtended (MCNPX) code. In the process of our research, an industrial X-ray tube with maximum voltage of 300 kV and current of 5 mA was simulated. A 3-layer uniform plate including a polymer overcoat layer, a phosphor layer and a polycarbonate backing layer was also defined and simulated as the CR imaging plate. To model the image formation in the image plate, at first the absorbed dose was calculated in each pixel inside the phosphor layer of CR imaging plate using the mesh tally in MCNPX code and then was converted to gray value using a mathematical relationship determined in a separate procedure. To validate the simulation results, an experimental setup was designed and the images of two step wedges created out of aluminum and steel were captured by the experiments and compared with the simulations. The results show that the simulated images are in good agreement with the experimental ones demonstrating the ability of the proposed methodology for simulating an industrial X-ray imaging system. Copyright © 2018 Elsevier Ltd. All rights reserved.

Applications of Elpasolites as a Multimode Radiation Sensor

NASA Astrophysics Data System (ADS)

Guckes, Amber

This study consists of both computational and experimental investigations. The computational results enabled detector design selections and confirmed experimental results. The experimental results determined that the CLYC scintillation detector can be applied as a functional and field-deployable multimode radiation sensor. The computational study utilized MCNP6 code to investigate the response of CLYC to various incident radiations and to determine the feasibility of its application as a handheld multimode sensor and as a single-scintillator collimated directional detection system. These simulations include: • Characterization of the response of the CLYC scintillator to gamma-rays and neutrons; • Study of the isotopic enrichment of 7Li versus 6Li in the CLYC for optimal detection of both thermal neutrons and fast neutrons; • Analysis of collimator designs to determine the optimal collimator for the single CLYC sensor directional detection system to assay gamma rays and neutrons; Simulations of a handheld CLYC multimode sensor and a single CLYC scintillator collimated directional detection system with the optimized collimator to determine the feasibility of detecting nuclear materials that could be encountered during field operations. These nuclear materials include depleted uranium, natural uranium, low-enriched uranium, highly-enriched uranium, reactor-grade plutonium, and weapons-grade plutonium. The experimental study includes the design, construction, and testing of both a handheld CLYC multimode sensor and a single CLYC scintillator collimated directional detection system. Both were designed in the Inventor CAD software and based on results of the computational study to optimize its performance. The handheld CLYC multimode sensor is modular, scalable, low?power, and optimized for high count rates. Commercial?off?the?shelf components were used where possible in order to optimize size, increase robustness, and minimize cost. The handheld CLYC multimode sensor was successfully tested to confirm its ability for gamma-ray and neutron detection, and gamma?ray and neutron spectroscopy. The sensor utilizes wireless data transfer for possible radiation mapping and network?centric deployment. The handheld multimode sensor was tested by performing laboratory measurements with various gamma-ray sources and neutron sources. The single CLYC scintillator collimated directional detection system is portable, robust, and capable of source localization and identification. The collimator was designed based on the results of the computational study and is constructed with high density polyethylene (HDPE) and lead (Pb). The collimator design and construction allows for the directional detection of gamma rays and fast neutrons utilizing only one scintillator which is interchangeable. For this study, a CLYC-7 scintillator was used. The collimated directional detection system was tested by performing laboratory directional measurements with various gamma-ray sources, 252Cf and a 239PuBe source.

Effect of exit beam phase aberrations on coherent x-ray reconstructions of Au nanocrystals

NASA Astrophysics Data System (ADS)

Hruszkewycz, Stephan; Harder, Ross; Fuoss, Paul

2010-03-01

Current studies in coherent x-ray diffractive imaging (CXDI) are focusing on in-situ imaging under a variety of environmental conditions. Such studies often involve environmental sample chambers through which the x-ray beam must pass before and after interacting with the sample: i.e. cryostats or high pressure cells. Such sample chambers usually contain polycrystalline x-ray windows with structural imperfections that can in turn interact with the diffracted beam. A phase object in the near field that interacts with the beam exiting the sample can introduce distortions at the detector plane that may affect coherent reconstructions. We investigate the effects of a thin beryllium membrane on the coherent exit beam of a gold nanoparticle. We compare three dimensional reconstructions from experimental diffraction patterns measured with and without a 380 micron thick Be dome and find that the reconstructions are reproducible within experimental errors. Simulated near-field distortions of the exit beam consistent with micron sized voids in Be establish a ``worst case scenario'' where distorted diffraction patterns inhibit accurate inversions.

Long pulse Soft X-ray Emission from Laser Generated Irradiated Gold Foils

NASA Astrophysics Data System (ADS)

Davis, Joshua; Frank, Yechiel; Raicher, Erez; Fraenkel, Moshe; Keiter, Paul; Klein, Sallee; Drake, R. P.; Shvarts, Dov

2016-10-01

Long pulse soft x-ray sources (SXS) allow for flexibility in high-energy-density experimental designs by providing a means of driving matter to the high temperatures needed, for example to study radiation waves in different materials. SXSs can be made by using lasers to heat a high-Z thin foil, which then acts as a quasi-blackbody emitter. Previous studies of the x-ray emission characteristics of gold foils have focused on laser pulses of 1ns or less. We performed experiments using a 6.0ns laser pulse with energy of 2kJ on the Omega-60 system to generate and characterize multi-ns laser heated Au foils of thicknesses between 0.5-2.0 μm. We measured the 2D spatial profile of the emission with a soft x-ray camera and the time history of the emission with the Dante photodiode array . Effective temperatures for the emission were then calculated using the Dante measurements. Discussion of experimental results and a comparison with 1-D Rad-Hydro NLTE simulations will be presented.

Experimental Observation of Bulk Liquid Water Structure in ``No Man's Land''

NASA Astrophysics Data System (ADS)

Sellberg, Jonas; McQueen, Trevor; Huang, Congcong; Loh, Duane; Laksmono, Hartawan; Sierra, Raymond; Hampton, Christina; Starodub, Dmitri; Deponte, Daniel; Martin, Andrew; Barty, Anton; Wikfeldt, Thor; Schlesinger, Daniel; Pettersson, Lars; Beye, Martin; Nordlund, Dennis; Weiss, Thomas; Feldkamp, Jan; Caronna, Chiara; Seibert, Marvin; Messerschmidt, Marc; Williams, Garth; Boutet, Sebastien; Bogan, Michael; Nilsson, Anders

2013-03-01

Experiments on pure bulk water below about 235 K have so far been difficult: water crystallization occurs very rapidly below the homogeneous nucleation temperature of 232 K and above 160 K, leading to a ``no man's land'' devoid of experimental results regarding the structure. Here, we demonstrate a new, general experimental approach to study the structure of liquid states at supercooled conditions below their limit of homogeneous nucleation. We use femtosecond x-ray pulses generated by the LCLS x-ray laser to probe evaporatively cooled droplets of supercooled bulk water and find experimental evidence for the existence of metastable bulk liquid water down to temperatures of 223 K in the previously largely unexplored ``no man's land''. We acknoweledge NSF (CHE-0809324), Office of Basic Energy Sciences, and the Swedish Research Council for financial support.

Ultrafast magnetodynamics with free-electron lasers

NASA Astrophysics Data System (ADS)

Malvestuto, Marco; Ciprian, Roberta; Caretta, Antonio; Casarin, Barbara; Parmigiani, Fulvio

2018-02-01

The study of ultrafast magnetodynamics has entered a new era thanks to the groundbreaking technological advances in free-electron laser (FEL) light sources. The advent of these light sources has made possible unprecedented experimental schemes for time-resolved x-ray magneto-optic spectroscopies, which are now paving the road for exploring the ultimate limits of out-of-equilibrium magnetic phenomena. In particular, these studies will provide insights into elementary mechanisms governing spin and orbital dynamics, therefore contributing to the development of ultrafast devices for relevant magnetic technologies. This topical review focuses on recent advancement in the study of non-equilibrium magnetic phenomena from the perspective of time-resolved extreme ultra violet (EUV) and soft x-ray spectroscopies at FELs with highlights of some important experimental results.

Time-resolved structural studies at synchrotrons and X-ray free electron lasers: opportunities and challenges

PubMed Central

Neutze, Richard; Moffat, Keith

2012-01-01

X-ray free electron lasers (XFELs) are potentially revolutionary X-ray sources because of their very short pulse duration, extreme peak brilliance and high spatial coherence, features that distinguish them from today’s synchrotron sources. We review recent time-resolved Laue diffraction and time-resolved wide angle X-ray scattering (WAXS) studies at synchrotron sources, and initial static studies at XFELs. XFELs have the potential to transform the field of time-resolved structural biology, yet many challenges arise in devising and adapting hardware, experimental design and data analysis strategies to exploit their unusual properties. Despite these challenges, we are confident that XFEL sources are poised to shed new light on ultrafast protein reaction dynamics. PMID:23021004

Studies on the effect of the axial magnetic field on the x-ray bremsstrahlung in a 2.45 GHz permanent magnet microwave ion source.

PubMed

Kumar, Narender; Rodrigues, G; Lakshmy, P S; Baskaran, R; Mathur, Y; Ahuja, R; Kanjilal, D

2014-02-01

A compact microwave ion source has been designed and developed for operation at a frequency of 2.45 GHz. The axial magnetic field is based on two permanent magnet rings, operating in the "off-resonance" mode and is tunable by moving the permanent magnets. In order to understand the electron energy distribution function, x-ray bremsstrahlung has been measured in the axial direction. Simulation studies on the x-ray bremsstrahlung have been carried out to compare with the experimental results. The effect of the axial magnetic field with respect to the microwave launching position and the position of the extraction electrode on the x-ray bremsstrahlung have been studied.

Development of an X-ray fluorescence holographic measurement system for protein crystals

NASA Astrophysics Data System (ADS)

Sato-Tomita, Ayana; Shibayama, Naoya; Happo, Naohisa; Kimura, Koji; Okabe, Takahiro; Matsushita, Tomohiro; Park, Sam-Yong; Sasaki, Yuji C.; Hayashi, Kouichi

2016-06-01

Experimental procedure and setup for obtaining X-ray fluorescence hologram of crystalline metalloprotein samples are described. Human hemoglobin, an α2β2 tetrameric metalloprotein containing the Fe(II) heme active-site in each chain, was chosen for this study because of its wealth of crystallographic data. A cold gas flow system was introduced to reduce X-ray radiation damage of protein crystals that are usually fragile and susceptible to damage. A χ-stage was installed to rotate the sample while avoiding intersection between the X-ray beam and the sample loop or holder, which is needed for supporting fragile protein crystals. Huge hemoglobin crystals (with a maximum size of 8 × 6 × 3 mm3) were prepared and used to keep the footprint of the incident X-ray beam smaller than the sample size during the entire course of the measurement with the incident angle of 0°-70°. Under these experimental and data acquisition conditions, we achieved the first observation of the X-ray fluorescence hologram pattern from the protein crystals with minimal radiation damage, opening up a new and potential method for investigating the stereochemistry of the metal active-sites in biomacromolecules.

Morphogen-based simulation model of ray growth and joint patterning during fin development and regeneration.

PubMed

Rolland-Lagan, Anne-Gaëlle; Paquette, Mathieu; Tweedle, Valerie; Akimenko, Marie-Andrée

2012-03-01

The fact that some organisms are able to regenerate organs of the correct shape and size following amputation is particularly fascinating, but the mechanism by which this occurs remains poorly understood. The zebrafish (Danio rerio) caudal fin has emerged as a model system for the study of bone development and regeneration. The fin comprises 16 to 18 bony rays, each containing multiple joints along its proximodistal axis that give rise to segments. Experimental observations on fin ray growth, regeneration and joint formation have been described, but no unified theory has yet been put forward to explain how growth and joint patterns are controlled. We present a model for the control of fin ray growth during development and regeneration, integrated with a model for joint pattern formation, which is in agreement with published, as well as new, experimental data. We propose that fin ray growth and joint patterning are coordinated through the interaction of three morphogens. When the model is extended to incorporate multiple rays across the fin, it also accounts for how the caudal fin acquires its shape during development, and regains its correct size and shape following amputation.

Emerging trends in X-ray spectroscopic studies of plasma produced by intense laser beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, V., E-mail: arora@rrcat.gov.in; Chakera, J. A.; Naik, P. A.

2015-07-31

X-ray line emission from hot dense plasmas, produced by ultra-short high intensity laser systems, has been studied experimentally in recent years for applications in materials science as well as for back-lighter applications. By virtue of the CPA technology, several laser facilities delivering pulses with peak powers in excess of one petawatt (focused intensities > 10{sup 20} W-cm{sup −2}) have either been commissioned across the globe during the last few years or are presently under construction. On the other hand, hard x-ray sources on table top, generating ultra-short duration x-rays at a repetition rate up to 10 kHz, are routinely available formore » time resolved x-ray diffraction studies. In this paper, the recent experiments on x-ray spectroscopic studies of plasma produced by 45 fs, Ti:sapphire laser pulses (focused iintensity > 10{sup 18} W-cm{sup −2}) at RRCAT Indore will be presented.« less

Measurements of Atomic Rayleigh Scattering Cross-Sections: A New Approach Based on Solid Angle Approximation and Geometrical Efficiency

NASA Astrophysics Data System (ADS)

Rao, D. V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Seltzer, S. M.; Hubbell, J. H.; Cesareo, R.; Brunetti, A.; Gigante, G. E.

Atomic Rayleigh scattering cross-sections for low, medium and high Z atoms are measured in vacuum using X-ray tube with a secondary target as an excitation source instead of radioisotopes. Monoenergetic Kα radiation emitted from the secondary target and monoenergetic radiation produced using two secondary targets with filters coupled to an X-ray tube are compared. The Kα radiation from the second target of the system is used to excite the sample. The background has been reduced considerably and the monochromacy is improved. Elastic scattering of Kα X-ray line energies of the secondary target by the sample is recorded with Hp Ge and Si (Li) detectors. A new approach is developed to estimate the solid angle approximation and geometrical efficiency for a system with experimental arrangement using X-ray tube and secondary target. The variation of the solid angle is studied by changing the radius and length of the collimators towards and away from the source and sample. From these values the variation of the total solid angle and geometrical efficiency is deduced and the optimum value is used for the experimental work. The efficiency is larger because the X-ray fluorescent source acts as a converter. Experimental results based on this system are compared with theoretical estimates and good agreement is observed in between them.

Photon statistics and speckle visibility spectroscopy with partially coherent X-rays.

PubMed

Li, Luxi; Kwaśniewski, Paweł; Orsi, Davide; Wiegart, Lutz; Cristofolini, Luigi; Caronna, Chiara; Fluerasu, Andrei

2014-11-01

A new approach is proposed for measuring structural dynamics in materials from multi-speckle scattering patterns obtained with partially coherent X-rays. Coherent X-ray scattering is already widely used at high-brightness synchrotron lightsources to measure dynamics using X-ray photon correlation spectroscopy, but in many situations this experimental approach based on recording long series of images (i.e. movies) is either not adequate or not practical. Following the development of visible-light speckle visibility spectroscopy, the dynamic information is obtained instead by analyzing the photon statistics and calculating the speckle contrast in single scattering patterns. This quantity, also referred to as the speckle visibility, is determined by the properties of the partially coherent beam and other experimental parameters, as well as the internal motions in the sample (dynamics). As a case study, Brownian dynamics in a low-density colloidal suspension is measured and an excellent agreement is found between correlation functions measured by X-ray photon correlation spectroscopy and the decay in speckle visibility with integration time obtained from the analysis presented here.

SLAC All Access: Atomic, Molecular and Optical Science Instrument

ScienceCinema

Bozek, John

2018-02-13

John Bozek, a staff scientist at SLAC's Linac Coherent Light Source (LCLS) X-ray laser who manages the LCLS Soft X-ray Department, takes us behind the scenes at the Atomic, Molecular and Optical Science (AMO) instrument, the first of six experimental stations now operating at LCLS. Samples used in AMO experiments include atoms, molecules, clusters, and nanoscale objects such as protein crystals or viruses. Science performed at AMO includes fundamental studies of light-matter interactions in the extreme X-ray intensity of the LCLS pules, time-resolved studies of increasingly charged states of atoms and molecules, X-ray diffraction imaging of nanocrystals, and single-shot imaging of a variety of objects.

The Effect of Experimental Variables on Industrial X-Ray Micro-Computed Sensitivity

NASA Technical Reports Server (NTRS)

Roth, Don J.; Rauser, Richard W.

2014-01-01

A study was performed on the effect of experimental variables on radiographic sensitivity (image quality) in x-ray micro-computed tomography images for a high density thin wall metallic cylinder containing micro-EDM holes. Image quality was evaluated in terms of signal-to-noise ratio, flaw detectability, and feature sharpness. The variables included: day-to-day reproducibility, current, integration time, voltage, filtering, number of frame averages, number of projection views, beam width, effective object radius, binning, orientation of sample, acquisition angle range (180deg to 360deg), and directional versus transmission tube.

Current developments and tests of small x-ray optical systems for space applications

NASA Astrophysics Data System (ADS)

Pina, L.; Hudec, R.; Inneman, A.; Doubravová, D.; Marsikova, V.

2017-05-01

The paper addresses the X-ray monitoring for astrophysical applications. A novel approach based on the use of 1D and 2D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV was further studied. Wide-field optical system of this type has not been used in space yet. Designed wide-field optical system combined with Timepix X-ray detector is described together with latest experimental results obtained during laboratory tests. Proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is the only solution in cases where intensity of impinging X-ray radiation is below the sensitivity of the detector, e.g. while monitoring astrophysical objects in space, or phenomena in the Earth's atmosphere. The optical system is considered to be used in a student rocket experiment.

Multi-keV X-ray area source intensity at SGII laser facility

NASA Astrophysics Data System (ADS)

Wang, Rui-rong; An, Hong-hai; Xie, Zhi-yong; Wang, Wei

2018-05-01

Experiments for investigating the feasibility of multi-keV backlighters for several different metallic foil targets were performed at the Shenguang II (SGII) laser facility in China. Emission spectra in the energy range of 1.65-7.0 keV were measured with an elliptically bent crystal spectrometer, and the X-ray source size was measured with a pinhole camera. The X-ray intensity near 4.75 keV and the X-ray source size for titanium targets at different laser intensity irradiances were studied. By adjusting the total laser energy at a fixed focal spot size, laser intensity in the range of 1.5-5.0 × 1015 W/cm2, was achieved. The results show that the line emission intensity near 4.75 keV and the X-ray source size are dependent on the laser intensity and increase as the laser intensity increases. However, an observed "peak" in the X-ray intensity near 4.75 keV occurs at an irradiance of 4.0 × 1015 W/cm2. For the employed experimental conditions, it was confirmed that the laser intensity could play a significant role in the development of an efficient multi-keV X-ray source. The experimental results for titanium indicate that the production of a large (˜350 μm in diameter) intense backlighter source of multi-keV X-rays is feasible at the SGII facility.

An Improved NDE (Non-Destructive Evaluation) Capability for Aerospace Components.

DTIC Science & Technology

1984-12-21

proposed design will use the scintillator/fiber-optic Reticon detector which was investigated in the eperimental studies discussed above. The x rays...practical operation. Experimental studies of a microfocal x-ray source and the SFRD pinpointed current proklems and capabilities. A conceptual design ...authors would like to acknowledge the following important contributions to this effort: Chuck Isaacson for his help in the design and implementation of

Cation distribution in NiZn-ferrite films via extended x-ray absorption fine structure

NASA Astrophysics Data System (ADS)

Harris, V. G.; Koon, N. C.; Williams, C. M.; Zhang, Q.; Abe, M.; Kirkland, J. P.

1996-04-01

We have applied extended x-ray absorption fine structure (EXAFS) spectroscopy to study the cation distribution in a series of spin-sprayed NiZn-ferrite films. A least-squares fitting of experimental EXAFS data with theoretical, multiple-scattering, EXAFS data allowed the quantitative determination of site distributions for all transition metal cations.

X-Ray Absorption Measured in the Resonant Auger Scattering Mode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hikosaka, Y.; Shigemasa, E.; Kaneyasu, T.

2008-08-15

We report both experimental and theoretical studies on x-ray absorption measured in the resonant Auger scattering mode of gas phase carbon monoxide near the O1s{yields}2{pi} region. Both experiment and theory display a crucial difference between the x-ray absorption profiles obtained in the conventional and resonant scattering modes. Lifetime vibrational interference is the main source of the difference. It is demonstrated that such interference, which arises from a coherent excitation to overlapping intermediate levels, ruins the idea for obtaining x-ray absorption spectra in a lifetime broadening free regime.

Gamma-ray astronomy with a large muon detector in the ARGO-YBJ experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di Sciascio, G.; Di Girolamo, T.; Megna, R.

2005-02-21

The ARGO-YBJ experiment, currently under construction at the YangBaJing Laboratory (Tibet, P.R. China, 4300 m a.s.l.), could be upgraded with a large ({approx} 2500 m2) muon detector both to extend the sensitivity to {gamma}-ray sources to energies greater than {approx} 20 TeV and to perform a cosmic ray primary composition study. In this paper we present an evaluation of the rejection power for proton-induced showers achievable with the upgraded ARGO-YBJ detector. Minimum detectable {gamma}-ray fluxes are calculated for different experimental setups.

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

NASA Technical Reports Server (NTRS)

Wargelin, B.

2002-01-01

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

Advanced X-ray Spectroscopic Methods for Studying Iron-Sulfur-Containing Proteins and Model Complexes.

PubMed

DeBeer, Serena

2018-01-01

In this chapter, a brief overview of X-ray spectroscopic methods that may be utilized to obtain insight into the geometric and electronic structure of iron-sulfur proteins is provided. These methods include conventional methods, such as metal and ligand K-edge X-ray absorption, as well as more advanced methods including nonresonant and resonant X-ray emission. In each section, the basic information content of the spectra is highlighted and important experimental considerations are discussed. Throughout the chapter, recent applications to iron-sulfur-containing models and proteins are highlighted. © 2018 Elsevier Inc. All rights reserved.

X-Ray Spectroscopies of Warm Dense Matter

NASA Astrophysics Data System (ADS)

Hoidn, Oliver

This dissertation provides a perspective on the role of x-ray spectroscopy and diffraction diagnostics in experimental studies of warm dense matter (WDM). The primary focus of the work I discuss is the development of techniques to measure the structure and state variables of laboratory-generated WDM with a view towards both phenomenlogy and placing contraints on theoretical models. I present techniques adapted to two experimental venues for WDM studies: large-scale laser plasma facilities and x-ray free electron lasers. My focus is on the latter, in the context of which I have studied a dose enhancement technique that exploits nonlocal heat transport in nanostructured targets and considered several aspects of optimizing x-ray diffraction measurements. This work came into play in beam runs at the Linac Coherent Light Source (LCLS) in which my group performed x-ray diffraction studies of several materials heated to eV-scale temperatures. The results from these experiments include confirmation of the persistence of long-range crystalline order upon heating of metal oxides to tens of eV temperarures on the 40 fs timescale. One material, MgO, additionally manifested a surprising anomalous early onset in delocalization of valence charge density, contradicting predictions of all models based on either ground state electronic structure or (high-energy density) plasma physics. This particular result outlines a future path for studies of ordered insulators heated to temperatures on the order of the band gap. Such experiments will offer strong tests of electronic strucure theory, implementing a scientific approach that sees measurement of real-space charge density via x-ray diffraction (XRD) as a particularly effectve means to constrain density functional theory (DFT)-based modeling of the solid state/plasma transitional regime.

Imaging efficiency of an X-ray contrast agent-incorporated polymeric microparticle.

PubMed

Ahn, Sungsook; Jung, Sung Yong; Lee, Jin Pyung; Lee, Sang Joon

2011-01-01

Biocompatible polymeric encapsulants have been widely used as a delivery vehicle for a variety of drugs and imaging agents. In this study, X-ray contrast agent (iopamidol) is encapsulated into a polymeric microparticle (polyvinyl alcohol) as a particulate flow tracer in synchrotron X-ray imaging system. The physical properties of the designed microparticles are investigated and correlated with enhancement in the imaging efficiency by experimental observation and theoretical interpretation. The X-ray absorption ability of the designed microparticle is assessed by Beer-Lambert-Bouguer law. Particle size, either in dried state or in solvent, primarily dominates the X-ray absorption ability under the given condition, thus affecting imaging efficiency of the designed X-ray contrast flow tracers. Copyright © 2011 John Wiley & Sons, Ltd.

Feasibility study for mega-electron-volt electron beam tomography.

PubMed

Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

2012-09-01

Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

Silicon drift detector based X-ray spectroscopy diagnostic system for the study of non-thermal electrons at Aditya tokamak.

PubMed

Purohit, S; Joisa, Y S; Raval, J V; Ghosh, J; Tanna, R; Shukla, B K; Bhatt, S B

2014-11-01

Silicon drift detector based X-ray spectrometer diagnostic was developed to study the non-thermal electron for Aditya tokamak plasma. The diagnostic was mounted on a radial mid plane port at the Aditya. The objective of diagnostic includes the estimation of the non-thermal electron temperature for the ohmically heated plasma. Bi-Maxwellian plasma model was adopted for the temperature estimation. Along with that the study of high Z impurity line radiation from the ECR pre-ionization experiments was also aimed. The performance and first experimental results from the new X-ray spectrometer system are presented.

Experimental results of use of triple-energy X-ray beam with K-edge filter in multi-energy imaging

NASA Astrophysics Data System (ADS)

Kim, D.; Lee, S.; Jeon, P.-H.

2016-04-01

Multi-energy imaging is useful for contrast enhancement of lesions, quantitative analysis of specific materials and material separation in the human body. Generally, dual-energy methods are applied to discriminating two materials, but this method cannot discriminate more than two materials. Photon-counting detectors provide spectral information from polyenergetic X-rays using multiple energy bins. In this work, we developed triple-energy X-ray beams using a filter with K-edge energy and applied them experimentally. The energy spectra of triple-energy X-ray beams were assessed by using a spectrometer. The designed triple-energy X-ray beams were validated by measuring quantitative evaluations with mean energy ratio (MER), contrast variation ratio (CVR) and exposure efficiency (EE). Then, triple-energy X-ray beams were used to extract density map of three materials, iodine (I), aluminum (Al) and polymethyl methacrylate (PMMA). The results of the thickness density maps obtained with the developed triple-energy X-ray beams were compared to those acquired using the photon-counting method. As a result, it was found experimentally that the proposed triple-energy X-ray beam technique can separate the three materials as well as the photon-counting method.

Calibration and performance of a real-time gamma-ray spectrometry water monitor using a LaBr3(Ce) detector

NASA Astrophysics Data System (ADS)

Prieto, E.; Casanovas, R.; Salvadó, M.

2018-03-01

A scintillation gamma-ray spectrometry water monitor with a 2″ × 2″ LaBr3(Ce) detector was characterized in this study. This monitor measures gamma-ray spectra of river water. Energy and resolution calibrations were performed experimentally, whereas the detector efficiency was determined using Monte Carlo simulations with EGS5 code system. Values of the minimum detectable activity concentrations for 131I and 137Cs were calculated for different integration times. As an example of the monitor performance after calibration, a radiological increment during a rainfall episode was studied.

Structural studies of liquid Co–Sn alloys

PubMed Central

Yakymovych, A.; Shtablavyi, I.; Mudry, S.

2014-01-01

An analysis of the structure features of liquid Co–Sn alloys has been performed by means of X-ray diffraction method, viscosity coefficient analysis and computer simulation method. The X-ray diffraction investigations were carried out over a wide concentration range at the temperature 1473 K. It was found that the structure of these alloys can be described in the frame of independent X-ray scattering model. The viscosity coefficient was calculated by an excess entropy scaling and compared with experimental data. PMID:25328282

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

NASA Technical Reports Server (NTRS)

Wargelin, B.

2003-01-01

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

Towards shot-noise limited diffraction experiments with table-top femtosecond hard x-ray sources.

PubMed

Holtz, Marcel; Hauf, Christoph; Weisshaupt, Jannick; Salvador, Antonio-Andres Hernandez; Woerner, Michael; Elsaesser, Thomas

2017-09-01

Table-top laser-driven hard x-ray sources with kilohertz repetition rates are an attractive alternative to large-scale accelerator-based systems and have found widespread applications in x-ray studies of ultrafast structural dynamics. Hard x-ray pulses of 100 fs duration have been generated at the Cu K α wavelength with a photon flux of up to 10 9 photons per pulse into the full solid angle, perfectly synchronized to the sub-100-fs optical pulses from the driving laser system. Based on spontaneous x-ray emission, such sources display a particular noise behavior which impacts the sensitivity of x-ray diffraction experiments. We present a detailed analysis of the photon statistics and temporal fluctuations of the x-ray flux, together with experimental strategies to optimize the sensitivity of optical pump/x-ray probe experiments. We demonstrate measurements close to the shot-noise limit of the x-ray source.

Towards shot-noise limited diffraction experiments with table-top femtosecond hard x-ray sources

PubMed Central

Holtz, Marcel; Hauf, Christoph; Weisshaupt, Jannick; Salvador, Antonio-Andres Hernandez; Woerner, Michael; Elsaesser, Thomas

2017-01-01

Table-top laser-driven hard x-ray sources with kilohertz repetition rates are an attractive alternative to large-scale accelerator-based systems and have found widespread applications in x-ray studies of ultrafast structural dynamics. Hard x-ray pulses of 100 fs duration have been generated at the Cu Kα wavelength with a photon flux of up to 109 photons per pulse into the full solid angle, perfectly synchronized to the sub-100-fs optical pulses from the driving laser system. Based on spontaneous x-ray emission, such sources display a particular noise behavior which impacts the sensitivity of x-ray diffraction experiments. We present a detailed analysis of the photon statistics and temporal fluctuations of the x-ray flux, together with experimental strategies to optimize the sensitivity of optical pump/x-ray probe experiments. We demonstrate measurements close to the shot-noise limit of the x-ray source. PMID:28795079

Long-term effects of prenatal x-ray of human females. II. Growth and development.

PubMed

Meyer, M B; Tonascia, J

1981-09-01

Experimental studies and studies of survivors of in-utero exposure to atomic bomb blasts have shown significant stunting of growth and mental retardation following these exposures. Central nervous system damage following very low doses of x-ray at around the time of birth has also been observed in experimental animals. This long term follow-up studies of 1458 human females exposed in utero to diagnostic x-rays and of 1458 matched unexposed controls studied in Baltimore, Maryland, included measurements of height, weight and school achievement. Women who had been exposed to x-rays in utero were significantly shorter in their mid-twenties than were their matched, unexposed controls, even after adjustment for other social and economic factors. However, additional follow-up revealed that mothers of exposed women were also shorter than the control mothers. Short stature appeared to be a selective factor for x-ray during pregnancy (mostly pelvimetry, 1947-1952). Mothers' and daughters' heights were similarly correctly among exposed and control mother-daughter pairs, suggesting that the height differences between exposed daughters and their controls were due to these selective factor rather than to any direct effect of radiation on growth. Exposed women reported poorer school achievement than control women. However, except for a higher proportion of exposed women leaving school because of pregnancy, these measurements were no longer significantly different when rates were simultaneously adjusted for socioeconomic differences between exposed and control women.

Seismo-acoustic ray model benchmarking against experimental tank data.

PubMed

Camargo Rodríguez, Orlando; Collis, Jon M; Simpson, Harry J; Ey, Emanuel; Schneiderwind, Joseph; Felisberto, Paulo

2012-08-01

Acoustic predictions of the recently developed traceo ray model, which accounts for bottom shear properties, are benchmarked against tank experimental data from the EPEE-1 and EPEE-2 (Elastic Parabolic Equation Experiment) experiments. Both experiments are representative of signal propagation in a Pekeris-like shallow-water waveguide over a non-flat isotropic elastic bottom, where significant interaction of the signal with the bottom can be expected. The benchmarks show, in particular, that the ray model can be as accurate as a parabolic approximation model benchmarked in similar conditions. The results of benchmarking are important, on one side, as a preliminary experimental validation of the model and, on the other side, demonstrates the reliability of the ray approach for seismo-acoustic applications.

Analysis of monochromatic and quasi-monochromatic X-ray sources in imaging and therapy

NASA Astrophysics Data System (ADS)

Westphal, Maximillian; Lim, Sara; Nahar, Sultana; Orban, Christopher; Pradhan, Anil

2017-04-01

We studied biomedical imaging and therapeutic applications of recently developed quasi-monochromatic and monochromatic X-ray sources. Using the Monte Carlo code GEANT4, we found that the quasi-monochromatic 65 keV Gaussian X-ray spectrum created by inverse Compton scattering with relatavistic electron beams were capable of producing better image contrast with less radiation compared to conventional 120 kV broadband CT scans. We also explored possible experimental detection of theoretically predicted K α resonance fluorescence in high-Z elements using the European Synchrotron Research Facility with a tungsten (Z = 74) target. In addition, we studied a newly developed quasi-monochromatic source generated by converting broadband X-rays to monochromatic K α and β X-rays with a zirconium target (Z = 40). We will further study how these K α and K β dominated spectra can be implemented in conjunction with nanoparticles for targeted therapy. Acknowledgement: Ohio Supercomputer Center, Columbus, OH.

X-ray Constrained Extremely Localized Molecular Orbitals: Theory and Critical Assessment of the New Technique.

PubMed

Genoni, Alessandro

2013-07-09

Following the X-ray constrained wave function approach proposed by Jayatilaka, we have devised a new technique that allows to extract molecular orbitals strictly localized on small molecular fragments from sets of experimental X-ray structure factors amplitudes. Since the novel strategy enables to obtain electron distributions that have quantum mechanical features and that can be easily interpreted in terms of traditional chemical concepts, the method can be also considered as a new useful tool for the determination and the analysis of charge densities from high-resolution X-ray experiments. In this paper, we describe in detail the theory of the new technique, which, in comparison to our preliminary work, has been improved both treating the effects of isotropic secondary extinctions and introducing a new protocol to halt the fitting procedure against the experimental X-ray scattering data. The performances of the novel strategy have been studied both in function of the basis-sets flexibility and in function of the quality of the considered crystallographic data. The tests performed on four different systems (α-glycine, l-cysteine, (aminomethyl)phosphonic acid and N-(trifluoromethyl)formamide) have shown that the achievement of good statistical agreements with the experimental measures mainly depends on the quality of the crystal structures (i.e., geometry positions and thermal parameters) used in the X-ray constrained calculations. Finally, given the reliable transferability of the obtained Extremely Localized Molecular Orbitals (ELMOs), we envisage to exploit the novel approach to construct new ELMOs databases suited to the development of linear-scaling methods for the refinement of macromolecular crystal structures.

Structure, Mechanics and Flow Properties of Fractured Shale: Core-Scale Experimentation and In-situ Imaging

NASA Astrophysics Data System (ADS)

Abdelmalek, B. F.; Karpyn, Z.; Liu, S.

2014-12-01

Over the last several years, hydrocarbon exploitation and development in North America has been heavily centered on shale gas plays. However, the physical attributes of shales and their manifestation on transport properties and storage capacity remain poorly understood. Therefore, more experimentally based data are needed to fill the gaps in understanding both transport and storage of fluids in shale. The proposed work includes installation and testing of an experimental system which is capable of monitoring the dynamic evolution of shale core permeability under variable loading conditions and in coordination with X-ray microCT imaging. The goal of this study is to better understand and quantify fluid flow patterns and associated transport dynamics of fractured shale samples. The independent variables considered in this study are: mechanical loading and pore pressure. The mechanical response of shale core is captured for different loading paths. To best replicate the in-situ production scenario, the pore pressure is progressively depleted to mimic pressure decline. During the course of experimentation, permeability is estimated using the pulse-decay method under tri-axial stress boundary conditions. Simultaneously, X-ray microCT imaging is used with a tracer gas that is allowed to flow through the sample as an illuminating agent. In the presence of an illuminating agent, either Xenon or Krypton, the X-ray CT scanner can image fractures, global pathways and diffusional fronts in the matrix, as well as sorption sites that reflect heterogeneities in the sample and localized deformation. Anticipated results from these experiments will help quantify permeability evolution as a function of different loading conditions and pore pressure depletion. Also, the X-ray images will help visualize the change of flow patterns and the intensity of sorption as a function of mechanical loading and pore pressure.

Streaked x-ray backlighting with twin-slit imager for study of density profile and trajectory of low-density foam target filled with deuterium liquid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiraga, H.; Mahigashi, N.; Yamada, T.

2008-10-15

Low-density plastic foam filled with liquid deuterium is one of the candidates for inertial fusion target. Density profile and trajectory of 527 nm laser-irradiated planer foam-deuterium target in the acceleration phase were observed with streaked side-on x-ray backlighting. An x-ray imager employing twin slits coupled to an x-ray streak camera was used to simultaneously observe three images of the target: self-emission from the target, x-ray backlighter profile, and the backlit target. The experimentally obtained density profile and trajectory were in good agreement with predictions by one-dimensional hydrodynamic simulation code ILESTA-1D.

Protein hydration in solution: Experimental observation by x-ray and neutron scattering

PubMed Central

Svergun, D. I.; Richard, S.; Koch, M. H. J.; Sayers, Z.; Kuprin, S.; Zaccai, G.

1998-01-01

The structure of the protein–solvent interface is the subject of controversy in theoretical studies and requires direct experimental characterization. Three proteins with known atomic resolution crystal structure (lysozyme, Escherichia coli thioredoxin reductase, and protein R1 of E. coli ribonucleotide reductase) were investigated in parallel by x-ray and neutron scattering in H2O and D2O solutions. The analysis of the protein–solvent interface is based on the significantly different contrasts for the protein and for the hydration shell. The results point to the existence of a first hydration shell with an average density ≈10% larger than that of the bulk solvent in the conditions studied. Comparisons with the results of other studies suggest that this may be a general property of aqueous interfaces. PMID:9482874

Applications of “Tender” Energy (1-5 keV) X-ray Absorption Spectroscopy in Life Sciences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Northrup, Paul; Leri, Alessandra; Tappero, Ryan

The “tender” energy range of 1 to 5 keV, between the energy ranges of most “hard” (>5 keV) and “soft” (<1 keV) synchrotron X-ray facilities, offers some unique opportunities for synchrotron-based X-ray absorption fine structure spectroscopy in life sciences. In particular the K absorption edges of Na through Ca offer opportunities to study local structure, speciation, and chemistry of many important biological compounds, structures and processes. This is an area of largely untapped science, in part due to a scarcity of optimized facilities. Such measurements also entail unique experimental challenges. Lastly, this brief review describes the technique, its experimental challenges,more » recent progress in development of microbeam measurement capabilities, and several highlights illustrating applications in life sciences.« less

Applications of “Tender” Energy (1-5 keV) X-ray Absorption Spectroscopy in Life Sciences

DOE PAGES

Northrup, Paul; Leri, Alessandra; Tappero, Ryan

2016-02-15

The “tender” energy range of 1 to 5 keV, between the energy ranges of most “hard” (>5 keV) and “soft” (<1 keV) synchrotron X-ray facilities, offers some unique opportunities for synchrotron-based X-ray absorption fine structure spectroscopy in life sciences. In particular the K absorption edges of Na through Ca offer opportunities to study local structure, speciation, and chemistry of many important biological compounds, structures and processes. This is an area of largely untapped science, in part due to a scarcity of optimized facilities. Such measurements also entail unique experimental challenges. Lastly, this brief review describes the technique, its experimental challenges,more » recent progress in development of microbeam measurement capabilities, and several highlights illustrating applications in life sciences.« less

Detection efficiency vs. cathode and anode separation in cylindrical vacuum photodiodes used for measuring x-rays from plasma focus device.

PubMed

Borthakur, T K; Talukdar, N; Neog, N K; Rao, C V S; Shyam, A

2011-10-01

A qualitative study on the performance of cylindrical vacuum photodiodes (VPDs) for x-ray detection in plasma focus device has been carried out. Various parameters of VPD such as electrode's diameter, electrode's separation, and its sensitivity are experimentally tested in plasma focus environment. For the first time it is found experimentally that the electrode-separation in the lateral direction of the two coaxial electrodes of cylindrical VPD also plays an important role to increase the efficiency of the detector. The efficiency is found to be highest for the detector with smaller cathode-anode lateral gap (1.5 mm) with smaller photo cathode diameter (10 mm). A comparison between our VPD with PIN (BPX-65) diode as an x-ray detector has also been made.

Origin of Gamma-Ray Families Accompanied by Halos and Detected in Experiments with X-Ray Emulsion Chambers

NASA Astrophysics Data System (ADS)

Puchkov, V. S.; Pyatovsky, S. E.

2018-03-01

The phenomenon of gamma-ray families featuring halos that is observed in an experiment with x-ray emulsion chambers (XREC) in the Pamir experiment and in other XREC experiments is explained. The experimental properties of halos are analyzed via a comparison with the results of their simulation. It is shown that gamma-ray families featuring halos are predominantly produced (more than 96% of them) by protons and heliumnuclei. This makes it possible to employ the experimental properties of halos to estimate the fraction of protons and helium nuclei in the mass composition of primary cosmic radiation.

Lightning Initiation and Propagation

DTIC Science & Technology

2009-08-22

ray (gamma ray ) and multiple-station (>24) cosmic - ray - muon detection network (TERA) pl:esently in place. Upgrade TERA with LaBr3 detectors to...DATES COVERED 4. TITLE AND SUBTITLE Lightning Initistion and Propagation Including the Role of X- Rays , Gamma Rays , and Cosmic Rays 5a... rays , gamma rays , and cosmic rays in the initiation and propagation of lightning and in the phenomenology of thunderclouds. The experimental

Extreme ultraviolet resonant inelastic X-ray scattering (RIXS) at a seeded free-electron laser

DOE PAGES

Dell’Angela, M.; Hieke, F.; Malvestuto, M.; ...

2016-12-12

In the past few years, we have been witnessing an increased interest for studying materials properties under non-equilibrium conditions. Several well established spectroscopies for experiments in the energy domain have been successfully adapted to the time domain with sub-picosecond time resolution. Here we show the realization of high resolution resonant inelastic X-ray scattering (RIXS) with a stable ultrashort X-ray source such as an externally seeded free electron laser (FEL). We have designed and constructed a RIXS experimental endstation that allowed us to successfully measure the d-d excitations in KCoF 3 single crystals at the cobalt M 2,3-edge at FERMI FELmore » (Elettra-Sincrotrone Trieste, Italy). The FEL-RIXS spectra show an excellent agreement with the ones obtained from the same samples at the MERIXS endstation of the MERLIN beamline at the Advanced Light Source storage ring (Berkeley, USA). We established experimental protocols for performing time resolved RIXS experiments at a FEL source to avoid X ray-induced sample damage, while retaining comparable acquisition time to the synchrotron based measurements. Finally, we measured and modelled the influence of the FEL mixed electromagnetic modes, also present in externally seeded FELs, and the beam transport with ~120 meV experimental resolution achieved in the presented RIXS setup.« less

Anionic and cationic redox and interfaces in batteries: Advances from soft X-ray absorption spectroscopy to resonant inelastic scattering

NASA Astrophysics Data System (ADS)

Yang, Wanli; Devereaux, Thomas P.

2018-06-01

Recent advances in battery science and technology have triggered both the challenges and opportunities on studying the materials and interfaces in batteries. Here, we review the recent demonstrations of soft X-ray spectroscopy for studying the interfaces and electrode materials. The focus of this review is on the recently developed mapping of resonant inelastic X-ray scattering (mRIXS) as a powerful probe of battery chemistry with superior sensitivity. Six different channels of soft X-ray absorption spectroscopy (sXAS) are introduced for different experimental purposes. Although conventional sXAS channels remain effective tools for quantitative analysis of the transition-metal states and surface chemistry, we elaborate the limitations of sXAS in both cationic and anionic redox studies. Particularly, based on experimental findings in various electrodes, we show that sXAS is unreliable for studying oxygen redox. We then demonstrate the mRIXS as a reliable technique for fingerprinting oxygen redox and summarize several crucial observations. We conclude that mRIXS is the tool-of-choice to study both the practical issue on reversibility of oxygen redox and the fundamental nature of bulk oxygen states. We hope this review clarifies the popular misunderstanding on oxygen sXAS results of oxide electrodes, and establishes a reliable technique for detecting oxygen redox through mRIXS.

Evidence for Coordination and Redox Changes of Iron in Shocked Feldspar from Synchrotron MicroXANES

NASA Technical Reports Server (NTRS)

Delaney, J. S.; Dyar, M. D.; Hoerz, F.; Johnson, J. R.

2003-01-01

Shock modification of feldspar has been documented and experimentally reproduced in many studies since the recognition of maskelynite in Shergotty. Experimentally shocked feldspar samples have been well studied using chemical and crystallographic techniques. The crystallographic, site-specific characterization of major and minor elements is less well documented. We present early x-ray absorption (XAS) spectral data for a suite of albitite samples that were experimentally shocked at pressures between 17 and 50 Gpa.

The structure, vibrational spectra and nonlinear optical properties of the L-lysine × tartaric acid complex—Theoretical studies

NASA Astrophysics Data System (ADS)

Drozd, M.; Marchewka, M. K.

2006-05-01

The room temperature X-ray studies of L-lysine × tartaric acid complex are not unambiguous. The disorder of three atoms of carbon in L-lysine molecule is observed. These X-ray studies are ambiguous. The theoretical geometry study performed by DFT methods explain the most doubts which are connected with crystallographic measurements. The theoretical vibrational frequencies and potential energy distribution (PED) of L-lysine × tartaric acid were calculated by B3LYP method. The calculated frequencies were compared with experimental measured IR spectra. The complete assignment of the bands has been made on the basis of the calculated PED. The restricted Hartee-Fock (RHF) methods were used for calculation of the hyperpolarizability for investigated compound. The theoretical results are compared with experimental value of β.

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies.

PubMed

Sutton, Kristin A; Black, Paul J; Mercer, Kermit R; Garman, Elspeth F; Owen, Robin L; Snell, Edward H; Bernhard, William A

2013-12-01

Electron paramagnetic resonance (EPR) and online UV-visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV-visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5-0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. The observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure.

Hard x-ray response of a CdZnTe ring-drift detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Owens, A.; Hartog, R. den; Quarati, F.

We present the results of an experimental study of a special type of CdZnTe detector of hard x and {gamma} rays--A-drift detector. The device consists of a double ring electrode structure surrounding a central point anode with a guard plane surrounding the outer anode ring. The detector can be operated in two distinctively different modes of charge collection--pseudohemispherical and pseudodrift. We study the detector response profiles obtained by scanning the focused x-ray beam over the whole detector area, specifically the variations in count rate, peak position, and energy resolution for x rays from 10 to 100 keV. In addition, atmore » 662 keV the energy resolution was shown to be 4.8 keV, more than a factor of 2 better than for CdZnTe coplanar grid detectors. To interpret the experimental data, we derive an analytical expression for the spatial distribution of the electric field inside the detector and neglecting carrier diffusion, and identify carrier collection patterns for both modes of operation within the drift model approximation. We show that this model provides a good understanding of measured profiles.« less

X-ray examination of the stomach bubble after frequent experimental swallowing of saliva: the mechanism of aerophagia.

PubMed

Ogami, Junya; Ono, Shigeru; Naka, Naoko; Watanuki, Kei; Ishida, Satoshi

2005-12-01

While the mechanism of aerophagia remains unclear, the frequency of clenching has been reported to be increased when under stress. We hypothesized that, via the swallowing reflex, chronic air swallowing was induced through a "learned habit" of the oral cavity, which was acquired through psychological factors. This study examined whether the habitual repeated swallowing in the oral cavity was a process of aerophagia. After continuous experimental saliva swallowing, changes in the stomach bubble were examined by abdominal X-rays in a standing position. The subjects included 9 males and 10 females aged 20 to 36 years that were without organic disease in the pharynx and nasal cavity. X-ray images were digitized, and the area of the stomach bubble was measured by tracing. A close correlation was revealed in the stomach bubble area between posteroanterior and lateral views in six males (p<0.001, r = 0.910). In 3 males and 10 females, the area of the stomach bubble by posteroanterior view after 30 swallows was significantly increased compared with that before swallowing (p = 0.004). In the present study, abdominal X-rays confirmed that frequent saliva swallowing expanded the stomach bubble.

Gamma ray spectroscopy in astrophysics. [conferences

NASA Technical Reports Server (NTRS)

Cline, T. L. (Editor); Ramaty, R. (Editor)

1978-01-01

Experimental and theoretical aspects of gamma ray spectroscopy in high energy astrophysics are discussed. Line spectra from solar, stellar, planetary, and cosmic gamma rays are examined as well as HEAO investigations, the prospects of a gamma ray observatory, and follow-on X-ray experiments in space.

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutton, Kristin A.; Black, Paul J.; Mercer, Kermit R.

2013-12-01

Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage, to confirm a multi-track radiation-damage process and to develop a model of that process. Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV–visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5–0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. Themore » observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure.« less

Exploiting magnetic properties of Fe doping in zirconia. From first-principles simulations to the experimental growth and characterization of thin films

NASA Astrophysics Data System (ADS)

Sangalli, Davide; Cianci, Elena; Lamperti, Alessio; Ciprian, Roberta; Albertini, Franca; Casoli, Francesca; Lupo, Pierpaolo; Nasi, Lucia; Campanini, Marco; Debernardi, Alberto

2013-05-01

In this study we explore, both from theoretical and experimental side, the effect of Fe doping in ZrO2 (ZrO2:Fe). By means of first principles simulation, we study the magnetization density and the magnetic interaction between Fe atoms. We also consider how this is affected by the presence of oxygen vacancies and compare our findings with models based on impurity band [J.M.D. Coey, M. Venkatesan, C.B. Fitzgerald, Nat. Mater. 4, 173 (2005)] and carrier mediated magnetic interaction [T. Dietl, H. Ohno, F. Matsukura, J. Cibert, D. Ferrand, Science 287, 1019 (2000)]. Experimentally, thin films (≈20 nm) of ZrO2:Fe at high doping concentration are grown by atomic layer deposition. We provide experimental evidence that Fe is uniformly distributed in the ZrO2 by transmission electron microscopy and energy dispersive X-ray mapping, while X-ray diffraction evidences the presence of the fluorite crystal structure. Alternating gradient force magnetometer measurements show magnetic signal at room temperature, however, with low magnetic moment per atom. Results from experimental measures and theoretical simulations are compared.

Experimental validation of Monte Carlo (MANTIS) simulated x-ray response of columnar CsI scintillator screens

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freed, Melanie; Miller, Stuart; Tang, Katherine

Purpose: MANTIS is a Monte Carlo code developed for the detailed simulation of columnar CsI scintillator screens in x-ray imaging systems. Validation of this code is needed to provide a reliable and valuable tool for system optimization and accurate reconstructions for a variety of x-ray applications. Whereas previous validation efforts have focused on matching of summary statistics, in this work the authors examine the complete point response function (PRF) of the detector system in addition to relative light output values. Methods: Relative light output values and high-resolution PRFs have been experimentally measured with a custom setup. A corresponding set ofmore » simulated light output values and PRFs have also been produced, where detailed knowledge of the experimental setup and CsI:Tl screen structures are accounted for in the simulations. Four different screens were investigated with different thicknesses, column tilt angles, and substrate types. A quantitative comparison between the experimental and simulated PRFs was performed for four different incidence angles (0 deg., 15 deg., 30 deg., and 45 deg.) and two different x-ray spectra (40 and 70 kVp). The figure of merit (FOM) used measures the normalized differences between the simulated and experimental data averaged over a region of interest. Results: Experimental relative light output values ranged from 1.456 to 1.650 and were in approximate agreement for aluminum substrates, but poor agreement for graphite substrates. The FOMs for all screen types, incidence angles, and energies ranged from 0.1929 to 0.4775. To put these FOMs in context, the same FOM was computed for 2D symmetric Gaussians fit to the same experimental data. These FOMs ranged from 0.2068 to 0.8029. Our analysis demonstrates that MANTIS reproduces experimental PRFs with higher accuracy than a symmetric 2D Gaussian fit to the experimental data in the majority of cases. Examination of the spatial distribution of differences between the PRFs shows that the main reason for errors between MANTIS and the experimental data is that MANTIS-generated PRFs are sharper than the experimental PRFs. Conclusions: The experimental validation of MANTIS performed in this study demonstrates that MANTIS is able to reliably predict experimental PRFs, especially for thinner screens, and can reproduce the highly asymmetric shape seen in the experimental data. As a result, optimizations and reconstructions carried out using MANTIS should yield results indicative of actual detector performance. Better characterization of screen properties is necessary to reconcile the simulated light output values with experimental data.« less

High Resolution Higher Energy X-ray Microscope for Mesoscopic Materials

NASA Astrophysics Data System (ADS)

Snigireva, I.; Snigirev, A.

2013-10-01

We developed a novel X-ray microscopy technique to study mesoscopically structured materials, employing compound refractive lenses. The easily seen advantage of lens-based methodology is the possibility to retrieve high resolution diffraction pattern and real-space images in the same experimental setup. Methodologically the proposed approach is similar to the studies of crystals by high resolution transmission electron microscopy. The proposed microscope was applied for studying of mesoscopic materials such as natural and synthetic opals, inverted photonic crystals.

Correcting intensity loss errors in the absence of texture-free reference samples during pole figure measurement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saleh, Ahmed A., E-mail: asaleh@uow.edu.au

Even with the use of X-ray polycapillary lenses, sample tilting during pole figure measurement results in a decrease in the recorded X-ray intensity. The magnitude of this error is affected by the sample size and/or the finite detector size. These errors can be typically corrected by measuring the intensity loss as a function of the tilt angle using a texture-free reference sample (ideally made of the same alloy as the investigated material). Since texture-free reference samples are not readily available for all alloys, the present study employs an empirical procedure to estimate the correction curve for a particular experimental configuration.more » It involves the use of real texture-free reference samples that pre-exist in any X-ray diffraction laboratory to first establish the empirical correlations between X-ray intensity, sample tilt and their Bragg angles and thereafter generate correction curves for any Bragg angle. It will be shown that the empirically corrected textures are in very good agreement with the experimentally corrected ones. - Highlights: •Sample tilting during X-ray pole figure measurement leads to intensity loss errors. •Texture-free reference samples are typically used to correct the pole figures. •An empirical correction procedure is proposed in the absence of reference samples. •The procedure relies on reference samples that pre-exist in any texture laboratory. •Experimentally and empirically corrected textures are in very good agreement.« less

Error analysis and prevention of cosmic ion-induced soft errors in static CMOS RAMs

NASA Astrophysics Data System (ADS)

Diehl, S. E.; Ochoa, A., Jr.; Dressendorfer, P. V.; Koga, P.; Kolasinski, W. A.

1982-12-01

Cosmic ray interactions with memory cells are known to cause temporary, random, bit errors in some designs. The sensitivity of polysilicon gate CMOS static RAM designs to logic upset by impinging ions has been studied using computer simulations and experimental heavy ion bombardment. Results of the simulations are confirmed by experimental upset cross-section data. Analytical models have been extended to determine and evaluate design modifications which reduce memory cell sensitivity to cosmic ions. A simple design modification, the addition of decoupling resistance in the feedback path, is shown to produce static RAMs immune to cosmic ray-induced bit errors.

Estimation of identification limit for a small-type OSL dosimeter on the medical images by measurement of X-ray spectra.

PubMed

Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

2016-07-01

Our aim in this study is to derive an identification limit on a dosimeter for not disturbing a medical image when patients wear a small-type optically stimulated luminescence (OSL) dosimeter on their bodies during X-ray diagnostic imaging. For evaluation of the detection limit based on an analysis of X-ray spectra, we propose a new quantitative identification method. We performed experiments for which we used diagnostic X-ray equipment, a soft-tissue-equivalent phantom (1-20 cm), and a CdTe X-ray spectrometer assuming one pixel of the X-ray imaging detector. Then, with the following two experimental settings, corresponding X-ray spectra were measured with 40-120 kVp and 0.5-1000 mAs at a source-to-detector distance of 100 cm: (1) X-rays penetrating a soft-tissue-equivalent phantom with the OSL dosimeter attached directly on the phantom, and (2) X-rays penetrating only the soft-tissue-equivalent phantom. Next, the energy fluence and errors in the fluence were calculated from the spectra. When the energy fluence with errors concerning these two experimental conditions was estimated to be indistinctive, we defined the condition as the OSL dosimeter not being identified on the X-ray image. Based on our analysis, we determined the identification limit of the dosimeter. We then compared our results with those for the general irradiation conditions used in clinics. We found that the OSL dosimeter could not be identified under the irradiation conditions of abdominal and chest radiography, namely, one can apply the OSL dosimeter to measurement of the exposure dose in the irradiation field of X-rays without disturbing medical images.

Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

DOE PAGES

Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; ...

2015-09-21

In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach producesmore » robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).« less

Experimental investigation of a HOPG crystal fan for x-ray fluorescence molecular imaging

NASA Astrophysics Data System (ADS)

Rosentreter, Tanja; Müller, Bernhard; Schlattl, Helmut; Hoeschen, Christoph

2017-03-01

Imaging x-ray fluorescence generally generates a conflict between the best image quality or highest sensitivity and lowest possible radiation dose. Consequently many experimental studies investigating the feasibility of this molecular imaging method, deal with either monochromatic x-ray sources that are not practical in clinical environment or accept high x-ray doses in order to maintain the advantage of high sensitivity and producing high quality images. In this work we present a x-ray fluorescence imaging setup using a HOPG crystal fan construction consisting of a Bragg reflecting analyzer array together with a scatter reducing radial collimator. This method allows for the use of polychromatic x-ray tubes that are in general easily accessible in contrast to monochromatic x-ray sources such as synchrotron facilities. Moreover this energy-selecting device minimizes the amount of Compton scattered photons while simultaneously increasing the fluorescence signal yield, thus significantly reducing the signal to noise ratio. The aim is to show the feasibility of this approach by measuring the Bragg reflected Kα fluorescence signal of an object containing an iodine solution using a large area detector with moderate energy resolution. Contemplating the anisotropic energy distribution of background scattered x-rays we compare the detection sensitivity, applying two different detector angular configurations. Our results show that even for large area detectors with limited energy resolution, iodine concentrations of 0.12 % can be detected. However, the potentially large scan times and therefore high radiation dose need to be decreased in further investigations.

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

Numerical simulations of the hard X-ray pulse intensity distribution at the Linac Coherent Light Source

DOE PAGES

Pardini, Tom; Aquila, Andrew; Boutet, Sebastien; ...

2017-06-15

Numerical simulations of the current and future pulse intensity distributions at selected locations along the Far Experimental Hall, the hard X-ray section of the Linac Coherent Light Source (LCLS), are provided. Estimates are given for the pulse fluence, energy and size in and out of focus, taking into account effects due to the experimentally measured divergence of the X-ray beam, and measured figure errors of all X-ray optics in the beam path. Out-of-focus results are validated by comparison with experimental data. Previous work is expanded on, providing quantitatively correct predictions of the pulse intensity distribution. Numerical estimates in focus aremore » particularly important given that the latter cannot be measured with direct imaging techniques due to detector damage. Finally, novel numerical estimates of improvements to the pulse intensity distribution expected as part of the on-going upgrade of the LCLS X-ray transport system are provided. As a result, we suggest how the new generation of X-ray optics to be installed would outperform the old one, satisfying the tight requirements imposed by X-ray free-electron laser facilities.« less

Kinetic Modeling of the X-ray-induced Damage to a Metalloprotein

PubMed Central

Davis, Katherine M.; Kosheleva, Irina; Henning, Robert W.; Seidler, Gerald T.; Pushkar, Yulia

2013-01-01

It is well known that biological samples undergo x-ray-induced degradation. One of the fastest occurring x-ray-induced processes involves redox modifications (reduction or oxidation) of redox-active cofactors in proteins. Here we analyze room temperature data on the photoreduction of Mn ions in the oxygen evolving complex (OEC) of photosystem II, one of the most radiation damage sensitive proteins and a key constituent of natural photosynthesis in plants, green algae and cyanobacteria. Time-resolved x-ray emission spectroscopy with wavelength-dispersive detection was used to collect data on the progression of x-ray-induced damage. A kinetic model was developed to fit experimental results, and the rate constant for the reduction of OEC MnIII/IV ions by solvated electrons was determined. From this model, the possible kinetics of x-ray-induced damage at variety of experimental conditions, such as different rates of dose deposition as well as different excitation wavelengths, can be inferred. We observed a trend of increasing dosage threshold prior to the onset of x-ray-induced damage with increasing rates of damage deposition. This trend suggests that experimentation with higher rates of dose deposition is beneficial for measurements of biological samples sensitive to radiation damage, particularly at pink beam and x-ray FEL sources. PMID:23815809

X-ray microanalysis of porous materials using Monte Carlo simulations.

PubMed

Poirier, Dominique; Gauvin, Raynald

2011-01-01

Quantitative X-ray microanalysis models, such as ZAF or φ(ρz) methods, are normally based on solid, flat-polished specimens. This limits their use in various domains where porous materials are studied, such as powder metallurgy, catalysts, foams, etc. Previous experimental studies have shown that an increase in porosity leads to a deficit in X-ray emission for various materials, such as graphite, Cr(2) O(3) , CuO, ZnS (Ichinokawa et al., '69), Al(2) O(3) , and Ag (Lakis et al., '92). However, the mechanisms responsible for this decrease are unclear. The porosity by itself does not explain the loss in intensity, other mechanisms have therefore been proposed, such as extra energy loss by the diffusion of electrons by surface plasmons generated at the pores-solid interfaces, surface roughness, extra charging at the pores-solid interface, or carbon diffusion in the pores. However, the exact mechanism is still unclear. In order to better understand the effects of porosity on quantitative microanalysis, a new approach using Monte Carlo simulations was developed by Gauvin (2005) using a constant pore size. In this new study, the X-ray emissions model was modified to include a random log normal distribution of pores size in the simulated materials. This article presents, after a literature review of the previous works performed about X-ray microanalysis of porous materials, some of the results obtained with Gauvin's modified model. They are then compared with experimental results. Copyright © 2011 Wiley Periodicals, Inc.

Characterization of short-pulse laser-produced x-rays for diagnosing magnetically driven cylindrical isentropic compression

NASA Astrophysics Data System (ADS)

Sawada, Hiroshi; Daykin, Tyler; Bauer, Bruno; Beg, Farhat

2017-10-01

We have developed an experimental platform to study material properties of magnetically compressed cylinder using a 1 MA pulsed power generator Zebra and a 50 TW subpicosecond short-pulse laser Leopard at the UNR's Nevada Terawatt Facility. According to a MHD simulation, strong magnetic fields generated by 100 ns rise time Zebra current can quasi-isentropically compress a material to the strongly coupled plasma regime. Taking advantage of the cylindrical geometry, a metal rod can be brought to higher pressures than that in the planar geometry. To diagnose the compressed rod with high precision x-ray measurements, an initial laser-only experiment was carried out to characterize laser-produced x-rays. Interaction of a high-intensity, short-pulse laser with solids produces broadband and monochromatic x-rays with photon energies high enough to probe dense metal rods. Bremsstrahlung was measured with Imaging plate-based filter stack spectrometers and monochromatic 8.0 keV Cu K-alpha was recorded with an absolutely calibrated Bragg crystal spectrometer. The broadband x-ray source was applied to radiography of thick metal objects and different filter materials were tested. The experimental results and a design of a coupled experiment will be presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato-Tomita, Ayana, E-mail: ayana.sato@jichi.ac.jp, E-mail: shibayam@jichi.ac.jp, E-mail: hayashi.koichi@nitech.ac.jp; Shibayama, Naoya, E-mail: ayana.sato@jichi.ac.jp, E-mail: shibayam@jichi.ac.jp, E-mail: hayashi.koichi@nitech.ac.jp; Okabe, Takahiro

Experimental procedure and setup for obtaining X-ray fluorescence hologram of crystalline metalloprotein samples are described. Human hemoglobin, an α{sub 2}β{sub 2} tetrameric metalloprotein containing the Fe(II) heme active-site in each chain, was chosen for this study because of its wealth of crystallographic data. A cold gas flow system was introduced to reduce X-ray radiation damage of protein crystals that are usually fragile and susceptible to damage. A χ-stage was installed to rotate the sample while avoiding intersection between the X-ray beam and the sample loop or holder, which is needed for supporting fragile protein crystals. Huge hemoglobin crystals (with amore » maximum size of 8 × 6 × 3 mm{sup 3}) were prepared and used to keep the footprint of the incident X-ray beam smaller than the sample size during the entire course of the measurement with the incident angle of 0°-70°. Under these experimental and data acquisition conditions, we achieved the first observation of the X-ray fluorescence hologram pattern from the protein crystals with minimal radiation damage, opening up a new and potential method for investigating the stereochemistry of the metal active-sites in biomacromolecules.« less

Gold nanoclusters as contrast agents for fluorescent and X-ray dual-modality imaging.

PubMed

Zhang, Aili; Tu, Yu; Qin, Songbing; Li, Yan; Zhou, Juying; Chen, Na; Lu, Qiang; Zhang, Bingbo

2012-04-15

Multimodal imaging technique is an alternative approach to improve sensitivity of early cancer diagnosis. In this study, highly fluorescent and strong X-ray absorption coefficient gold nanoclusters (Au NCs) are synthesized as dual-modality imaging contrast agents (CAs) for fluorescent and X-ray dual-modality imaging. The experimental results show that the as-prepared Au NCs are well constructed with ultrasmall sizes, reliable fluorescent emission, high computed tomography (CT) value and fine biocompatibility. In vivo imaging results indicate that the obtained Au NCs are capable of fluorescent and X-ray enhanced imaging. Copyright © 2012 Elsevier Inc. All rights reserved.

The Tunka-Grande experiment

NASA Astrophysics Data System (ADS)

Monkhoev, R. D.; Budnev, N. M.; Chiavassa, A.; Dyachok, A. N.; Gafarov, A. R.; Gress, O. A.; Gress, T. I.; Grishin, O. G.; Ivanova, A. L.; Kalmykov, N. N.; Kazarina, Yu. A.; Korosteleva, E. E.; Kozhin, V. A.; Kuzmichev, L. A.; Lenok, V. V.; Lubsandorzhiev, B. K.; Lubsandorzhiev, N. B.; Mirgazov, R. R.; Mirzoyan, R.; Osipova, E. A.; Pakhorukov, A. L.; Panasyuk, M. I.; Pankov, L. V.; Poleschuk, V. A.; Popova, E. G.; Postnikov, E. B.; Prosin, V. V.; Ptuskin, V. S.; Pushnin, A. A.; Samoliga, V. S.; Semeney, Y. A.; Sveshnikova, L. G.; Silaev, A. A.; Silaev, A. A., Jr.; Skurikhin, A. V.; Sulakov, V. P.; Tabolenko, V. A.; Voronin, D. M.; Fedorov, O. L.; Spiering, C.; Zagorodnikov, A. V.; Zhurov, D. P.; Zurbanov, V. L.

2017-06-01

The investigation of energy spectrum and mass composition of primary cosmic rays in the energy range 1016-1018 eV and the search for diffuse cosmic gamma rays are of the great interest for understanding mechanisms and nature of high-energy particle sources, the problem of great importance in modern astrophysics. Tunka-Grande scintillator array is a part of the experimental complex TAIGA (Tunka Advanced Instrument for Cosmic Ray and Gamma Astronomy) which is located in the Tunka Valley, about 50 km from Lake Baikal. The purpose of this array is the study of diffuse gamma rays and cosmic rays of ultra-high energies by detecting extensive air showers. We describe the design, specifications of the read-out, data acquisition (DAQ) and control systems of the array.

Interpretation of the silver L X-ray spectrum

NASA Technical Reports Server (NTRS)

Chen, M. H.; Crasemann, B.; Aoyagi, M.; Mark, H.

1977-01-01

Silver L X-ray energies were calculated using theoretical binding energies from relaxed orbital relativistic Hartree-Fock-Slater calculations. Theoretical X-ray energies are compared with experimental results.

X-ray Absorption and Emission Spectroscopic Studies of [L2Fe2S2]n Model Complexes: Implications for the Experimental Evaluation of Redox States in Iron–Sulfur Clusters

PubMed Central

2016-01-01

Herein, a systematic study of [L2Fe2S2]n model complexes (where L = bis(benzimidazolato) and n = 2-, 3-, 4-) has been carried out using iron and sulfur K-edge X-ray absorption (XAS) and iron Kβ and valence-to-core X-ray emission spectroscopies (XES). These data are used as a test set to evaluate the relative strengths and weaknesses of X-ray core level spectroscopies in assessing redox changes in iron–sulfur clusters. The results are correlated to density functional theory (DFT) calculations of the spectra in order to further support the quantitative information that can be extracted from the experimental data. It is demonstrated that due to canceling effects of covalency and spin state, the information that can be extracted from Fe Kβ XES mainlines is limited. However, a careful analysis of the Fe K-edge XAS data shows that localized valence vs delocalized valence species may be differentiated on the basis of the pre-edge and K-edge energies. These findings are then applied to existing literature Fe K-edge XAS data on the iron protein, P-cluster, and FeMoco sites of nitrogenase. The ability to assess the extent of delocalization in the iron protein vs the P-cluster is highlighted. In addition, possible charge states for FeMoco on the basis of Fe K-edge XAS data are discussed. This study provides an important reference for future X-ray spectroscopic studies of iron–sulfur clusters. PMID:27097289

Soft x-ray holography and microscopy of biological cells

NASA Astrophysics Data System (ADS)

Chen, Jianwen; Gao, Hongyi; Xie, Honglan; Li, Ruxin; Xu, Zhizhan

2003-10-01

Some experimental results on soft X-ray microscopy and holography imaging of biological specimens are presented in the paper. As we know, due to diffraction effects, there exists a resolution limit determined by wavelength λ and numerical aperture NA in conventional optical microscopy. In order to improve resolution, the num erical aperture should be made as large as possible and the wavelength as short as possible. Owing to the shorter wavelength, X-rays provide the potential of higher resolution in X-ray microscopy, holography image and allow for exam ination the interior structures of thicker specimens. In the experiments, we used synchrotron radiation source in Hefei as light source. Soft X-rays come from a bending magnet in 800 M eV electron storage ring with characteristic wavelength of 2.4 nm. The continuous X-ray spectrums are monochromatized by a zone-plate and a pinhole with 300 m diameter. The experimental set-up is typical contact microscopic system, its main advantage is simplicity and no special optical element is needed. The specimens used in the experiments of microscopic imaging are the colibacillus, the gingko vascular hundle and the fritillaries ovary karyon. The specimen for holographic imaging is the spider filam ents. The basic structures of plant cells such as the cell walls, the cytoplasm and the karyon especially the joint structures between the cells are observed clearly. An experimental study on a thick biological specimen that is a whole sporule w ith the thickness of about 30 μm is performed. In the holographic experiments, the experimental setup is typical Gabor in-line holography. The specimen is placed in line with X-ray source, which provides both the reference w aves and specimen illum ination. The specimen is some spider filament, which adhere to a Si3N4 film. The recording medium is PM M A, which is placed at recording distance of about 400 μm from the specimen. The hologram s were reconstructed by digital method with 300 nm resolutions. A novel method for recording in-line hologram is proposed which is called X-ray in-line holography with zone-plate magnification in this paper. The magnification factor of the micro zone plate imaging is about 103. The transverse resolution can be 48 nm in this method.

High pressure and high temperature in situ X-ray diffraction studies in the Paris-Edinburgh cell using a laboratory X-ray source†

NASA Astrophysics Data System (ADS)

Toulemonde, Pierre; Goujon, Céline; Laversenne, Laetitia; Bordet, Pierre; Bruyère, Rémy; Legendre, Murielle; Leynaud, Olivier; Prat, Alain; Mezouar, Mohamed

2014-04-01

We have developed a new laboratory experimental set-up to study in situ the pressure-temperature phase diagram of a given pure element or compound, its associated phase transitions, or the chemical reactions involved at high pressure and high temperature (HP-HT) between different solids and liquids. This new tool allows laboratory studies before conducting further detailed experiments using more brilliant synchrotron X-ray sources or before kinetic studies. This device uses the diffraction of X-rays produced by a quasi-monochromatic micro-beam source operating at the silver radiation (λ(Ag)Kα 1, 2≈0.56 Å). The experimental set-up is based on a VX Paris-Edinburgh cell equipped with tungsten carbide or sintered diamond anvils and uses standard B-epoxy 5 or 7 mm gaskets. The diffracted signal coming from the compressed (and heated) sample is collected on an image plate. The pressure and temperature calibrations were performed by diffraction, using conventional calibrants (BN, NaCl and MgO) for determination of the pressure, and by crossing isochores of BN, NaCl, Cu or Au for the determination of the temperature. The first examples of studies performed with this new laboratory set-up are presented in the article: determination of the melting point of germanium and magnesium under HP-HT, synthesis of MgB2 or C-diamond and partial study of the P, T phase diagram of MgH2.

Stereoselective green synthesis and molecular structures of highly functionalized spirooxindole-pyrrolidine hybrids - A combined experimental and theoretical investigation

NASA Astrophysics Data System (ADS)

Kumar, Raju Suresh; Almansour, Abdulrahman I.; Arumugam, Natarajan; Soliman, Saied M.; Kumar, Raju Ranjith; Altaf, Mohammad; Ghabbour, Hazem A.; Krishnamoorthy, Bellie Sundaram

2018-01-01

Highly functionalized spirooxindole-pyrrolidine hybrids have been synthesized stereoselectively through a [3 + 2] cycloaddition strategy in an ionic liquid, 1-butyl-3-methylimidazolium bromide ([bmim]Br). The structure of these spiro heterocyclic hybrids was elucidated using one and two dimensional NMR spectroscopy, single crystal X-ray crystallographic studies and Density Functional Theory (DFT) calculations. The calculated geometric parameters are in good agreement with the experimental data obtained from the X-ray structures. The Natural Bond Orbital (NBO) calculations on these molecules confirm the electron rich carbonyl oxygen and electron deficient NH groups. The 1H and 13C NMR chemical shifts calculated using GIAO method are in good agreement with the experimental data. The DFT computed polarizability values also suggest the possible NLO activity of these molecules.

Cr/B 4C multilayer mirrors: Study of interfaces and X-ray reflectance

DOE PAGES

Burcklen, C.; Soufli, R.; Gullikson, E.; ...

2016-03-24

Here, we present an experimental study of the effect of layer interfaces on the x-ray reflectance in Cr/B 4C multilayer interference coatings with layer thicknesses ranging from 0.7 nm to 5.4 nm. The multilayers were deposited by magnetron sputtering and by ion beam sputtering. Grazing incidence x-ray reflectometry, soft x-ray reflectometry, and transmission electron microscopy reveal asymmetric multilayer structures with a larger B 4C-on-Cr interface, which we modeled with a 1–1.5 nm thick interfacial layer. Reflectance measurements in the vicinity of the Cr L 2,3 absorption edge demonstrate fine structure that is not predicted by simulations using the currently tabulatedmore » refractive index (optical constants) values for Cr.« less

Development and tests of x-ray multifoil optical system for 1D imaging (Conference Presentation)

NASA Astrophysics Data System (ADS)

Pína, Ladislav; Hudec, René; Inneman, Adolf J.; Baca, Tomas; Blazek, M.; Platkevic, M.; Sieger, Ladislav; Doubravova, Daniela; McEntaffer, Randall L.; Schultz, Ted B.; Dániel, Vladimír.

2016-09-01

The proposed wide-field optical system has not been used yet. Described novel approach is based on the use of 1D "Lobster eye" optics in combination with Timepix X-ray detector in the energy range 3 - 40 keV. The proposed project includes theoretical study and a functional sample of the Timepix X-ray detector with multifoil wide-field X-ray "Lobster eye" optics. Using optics to focus X-rays on a detector is necessary in cases where the intensity of impinging X-ray radiation is below the sensitivity of the detector without optic. Generally this is the case of very low light phenomena, or e.g. monitoring astrophysical objects in space. Namely, such optical system could find applications in laboratory spectroscopy systems or in a rocket space experiment. Designed wide-field optical system combined with Timepix X-ray detector is described together with experimental results obtained during laboratory tests.

INTERNATIONAL CONFERENCE ON ULTRASHORT HIGH-ENERGY RADIATION AND MATTER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wootton, A J

2004-01-15

The workshop is intended as a forum to discuss the latest experimental, theoretical and computational results related to the interaction of high energy radiation with matter. High energy is intended to mean soft x-ray and beyond, but important new results from visible systems will be incorporated. The workshop will be interdisciplinary amongst scientists from many fields, including: plasma physics; x-ray physics and optics; solid state physics and material science; biology ; quantum optics. Topics will include, among other subjects: understanding damage thresholds for x-ray interactions with matter developing {approx} 5 keV x-ray sources to investigate damage; developing {approx} 100 keVmore » Thomsom sources for material studies; developing short pulse (100 fs and less) x-ray diagnostics; developing novel X-ray optics; and developing models for the response of biological samples to ultra intense, sub ps x-rays high-energy radiation.« less

Tight-Binding Approach to Computational Materials Science, Symposium Held December 1-3, 1997, Boston, Massachusetts, USA. Volume 491

DTIC Science & Technology

1998-01-01

to their large unit size and to experimental difficulties in determining geometries of carbon-based complex materials because of the weak X - ray ...qualitative relationship between the calculated local density of states and the experimental X - ray pho- toelectron spectra (XPS) and the Bremsstrahlung...from interaction schemes and allows complete data sets from different sources (neutron or X - ray diffraction, chemical constraints) to be fitted. In

Relativistic effects on x-ray structure factors

NASA Astrophysics Data System (ADS)

Batke, Kilian; Eickerling, Georg

2016-04-01

Today, combined experimental and theoretical charge density studies based on quantum chemical calculations and x-ray diffraction experiments allow for the investigation of the topology of the electron density at subatomic resolution. When studying compounds containing transition metal elements, relativistic effects need to be adequately taken into account not only in quantum chemical calculations of the total electron density ρ ({r}), but also for the atomic scattering factors employed to extract ρ ({r}) from experimental x-ray diffraction data. In the present study, we investigate the magnitude of relativistic effects on x-ray structure factors and for this purpose {F}({{r}}*) have been calculated for the model systems M(C2H2) (M = Ni, Pd, Pt) from four-component molecular wave functions. Relativistic effects are then discussed by a comparison to structure factors obtained from a non-relativistic reference and different quasi-relativistic approximations. We show, that the overall effects of relativity on the structure factors on average amount to 0.81%, 1.51% and 2.78% for the three model systems under investigation, but that for individual reflections or reflection series the effects can be orders of magnitude larger. Employing the quasi-relativistic Douglas-Kroll-Hess second order or the zeroth order regular approximation Hamiltonian takes these effects into account to a large extend, reducing the differences between the (quasi-)relativistic and the non-relativistic result by one order of magnitude. In order to further determine the experimental significance of the results, the magnitude of the relativistic effects is compared to the changes of the model structure factor data when charge transfer and chemical bonding is taken into account by a multipolar expansion of {F}({{r}}*).

Studies on absorption coefficient near edge of multi elements

NASA Astrophysics Data System (ADS)

Eisa, M. H.; Shen, H.; Yao, H. Y.; Mi, Y.; Zhou, Z. Y.; Hu, T. D.; Xie, Y. N.

2005-12-01

X-ray absorption near edge structure (XANES) was used to study the near edge mass-absorption coefficients of seven elements, such as, Ti, V, Fe, Co, Ni, Cu and Zn. It is well known that, on the near edge absorption of element, when incident X-ray a few eV change can make the absorption coefficient an order magnitude alteration. So that, there are only a few points mass-absorption coefficient at the near edge absorption and that always average value in published table. Our results showed a wide range of data, the total measured data of mass-absorption coefficient of the seven elements was about 505. The investigation confirmed that XANES is useful technique for multi-element absorption coefficient measurement. Details of experimental methods and results are given and discussed. The experimental work has been performed at Beijing Synchrotron Radiation Facility. The measured values were compared with the published data. Good agreement between experimental results and published data is obtained.

Photon-in photon-out hard X-ray spectroscopy at the Linac Coherent Light Source

DOE PAGES

Alonso-Mori, Roberto; Sokaras, Dimosthenis; Zhu, Diling; ...

2015-04-15

X-ray free-electron lasers (FELs) have opened unprecedented possibilities to study the structure and dynamics of matter at an atomic level and ultra-fast timescale. Many of the techniques routinely used at storage ring facilities are being adapted for experiments conducted at FELs. In order to take full advantage of these new sources several challenges have to be overcome. They are related to the very different source characteristics and its resulting impact on sample delivery, X-ray optics, X-ray detection and data acquisition. Here it is described how photon-in photon-out hard X-ray spectroscopy techniques can be applied to study the electronic structure andmore » its dynamics of transition metal systems with ultra-bright and ultra-short FEL X-ray pulses. In particular, some of the experimental details that are different compared with synchrotron-based setups are discussed and illustrated by recent measurements performed at the Linac Coherent Light Source.« less

Experimental and theoretical investigation of the rocking curves measured for Mo K α X-ray characteristic lines in the double-crystal nondispersive scheme

NASA Astrophysics Data System (ADS)

Marchenkov, N. V.; Chukhovskii, F. N.; Blagov, A. E.

2015-03-01

The rocking curves (RCs) for Mo K α1 h Mo K α2 characteristic X-ray lines have been experimentally and theoretically studied in the nondispersive scheme of an X-ray double-crystal TPC-K diffractometer. The results of measurements and theoretical calculations of double-crystal RCs for characteristic X-rays from tubes with a molybdenum anode and different widths of slits show that a decrease in the slit width leads to an increase in the relative contribution of the Mo K α2-line RC in comparison with the intensity of the tails of the Mo K α1-line RC. It is shown that the second peak of the Mo K α2 line becomes increasingly pronounced in the tail of the Mo K α1-line RC with a decrease in the slit width. Two plane-parallel Si plates (input faces {110}, diffraction vector h <220>) were used as a monochromator crystal and a sample. The results of measuring double-crystal RCs are in good agreement with theoretical calculations.

Radiation hazards to man

NASA Technical Reports Server (NTRS)

Curtis, S. B.; Wilkinson, M. C.

1971-01-01

The secondary dose contribution expected from the heavy primaries of the galactic cosmic rays was evaluated by a calculational technique developed in this study. Improvements in the solar and galactic cosmic ray environments made possible by recent experimental and theoretical work are discussed and presented. The recommendations of the National Academy of Sciences' space radiation study panel, are used in conjunction with a shielding analysis, to evaluate the radiation status of an astronaut during the triple solar particle event of 10, 14, 16 July 1959.

A leaded apron for use in panoramic dental radiography.

PubMed

Whitcher, B L; Gratt, B M; Sickles, E A

1980-05-01

The leaded aprons currently available for use during dental radiography do not protect the thyroid gland from radiation. Conventional aprons may produce artifacts when used with panoramic dental x-ray units. This study measures the dose reduction obtained with an experimental leaded apron designed for use with panoramic dental x-ray units. Skin exposures measured at the thyroid and at the sternum were reduced with the use of the apron. Films produced during the study were free from apron artifacts.

Preliminary studies of radiation coupling between remote soft X-ray laser amplifiers

NASA Astrophysics Data System (ADS)

Cairns, G.; Lewis, C. L. S.; Macphee, A. G.; Neely, D.; Holden, M.; Krishnan, J.; Tallents, G. J.; Key, M. H.; Norreys, P. N.; Smith, C. G.; Zhang, J.; Holden, P. B.; Pert, G. J.; Plowes, J.; Ramsden, S. A.

1994-01-01

Coupling of a soft X-ray laser beam with a relaying concave mirror in a sequentially pumped amplifier geometry using the Ne-like Ge system has been studied experimentally. Preliminary observations indicate an increase in the spatial coherence of the amplified relayed beam. In addition, near-field imaging of one of the amplifier plasmas shows a double-lobed intensity pattern of the emergent beam indicating refractive guiding of the amplified beam with components both normal and tangential to the target surface.

Study of the structural, vibrational and thermodynamic properties of natroxalate mineral using density functional theory

NASA Astrophysics Data System (ADS)

Colmenero, Francisco; Timón, Vicente

2018-07-01

Natroxalate mineral, Na2C2O4, is a fundamental oxalate mineral widespread in nature, present in humans, animals and plants, as well as in naturally occurring minerals. The characterization of oxalate minerals is extraordinarily important since these organic minerals are indicators of environmental events and of the presence of biological activity, because they are commonly of biological origin. These minerals are currently under study to investigate the possible biological activity on Mars. The identification of these compounds is usually performed by X-ray diffraction and Raman spectroscopy. Theoretical calculations are of great value for the study and interpretation of the results of these experimental techniques. In this work, natroxalate mineral structure and Raman spectrum was studied by first principle calculations based on the density functional theory. The computed structure of natroxalate reproduces the one determined experimentally by X-ray diffraction (monoclinic symmetry, space group P21/c; lattice parameters a = 3.449 Å, b = 5.243 Å; c = 10.375 Å). Lattice parameters, bond lengths, bond angles and X-ray powder pattern were found to be in very good agreement with their experimental counterparts. Raman spectrum was then computed by means of density functional perturbation theory and compared with the experimental spectrum. Since the results were also found in agreement with the experimental data, a normal mode analysis of the theoretical spectra was carried out and used in order to assign the main bands of the Raman spectrum. The band found at about 567 cm-1, described as a single peak in previous experimental works, is shown clearly to have two contributing bands. Finally, two bands of the observed spectrum, located at the wavenumbers 1750 and 1358 cm-1, were not found in the theoretical spectrum. This is because these bands correspond to an overtone, 2ν1 (ν1 = 875 cm-1), and a combination band, ν1 + ν2 (ν1,ν2 = 875, 481 cm-1), respectively. Finally, the fundamental thermodynamic properties of natroxalate mineral were determined. The calculated specific heat at 298.15 K is in excellent agreement with the experimental value, the difference being less than 1%. Since for most of these properties there are not experimental values to compare with, their values were predicted.

Experimental study of spectral and spatial distribution of solar X-rays

NASA Technical Reports Server (NTRS)

Acton, L. W.; Catura, R. C.; Culhane, J. L.

1972-01-01

The study of the physical conditions within the solar corona and the development of instrumentation and technical expertise necessary for advanced studies of solar X-ray emission are reported. Details are given on the Aerobee-borne-X-ray spectrometer/monochromator and also on the observing program. Preliminary discussions of some results are presented and include studies of helium-like line emission, mapping O(VII) and Ne(IX) lines, survey of O(VII) and Ne(IX) lines, study of plage regions and small flares, and analysis of line emission from individual active regions. It is concluded that the use of large-area collimated Bragg spectrometers to scan narrow wavelength intervals and the capability of the SPARCS pointing control to execute a complex observing program are established.

Robust X-ray angular correlations for the study of meso-structures

DOE PAGES

Lhermitte, Julien R.; Tian, Cheng; Stein, Aaron; ...

2017-05-08

As self-assembling nanomaterials become more sophisticated, it is becoming increasingly important to measure the structural order of finite-sized assemblies of nano-objects. These mesoscale clusters represent an acute challenge to conventional structural probes, owing to the range of implicated size scales (10 nm to several micrometres), the weak scattering signal and the dynamic nature of meso-clusters in native solution environments. The high X-ray flux and coherence of modern synchrotrons present an opportunity to extract structural information from these challenging systems, but conventional ensemble X-ray scattering averages out crucial information about local particle configurations. Conversely, a single meso-cluster scatters too weakly tomore » recover the full diffraction pattern. Using X-ray angular cross-correlation analysis, it is possible to combine multiple noisy measurements to obtain robust structural information. This paper explores the key theoretical limits and experimental challenges that constrain the application of these methods to probing structural order in real nanomaterials. A metric is presented to quantify the signal-to-noise ratio of angular correlations, and it is used to identify several experimental artifacts that arise. In particular, it is found that background scattering, data masking and inter-cluster interference profoundly affect the quality of correlation analyses. A robust workflow is demonstrated for mitigating these effects and extracting reliable angular correlations from realistic experimental data.« less

An experimental assessment of the imaging quality of the low energy gamma-ray telescope ZEBRA

NASA Technical Reports Server (NTRS)

Butler, R. C.; Caroli, E.; Dicocco, G.; Natalucci, L.; Spada, G.; Spizzichino, A.; Stephen, J. B.; Carter, J. N.; Charalambous, P. M.; Dean, A. J.

1985-01-01

One gamma-ray detection plane of the ZEBRA telescope, consisting of nine position sensitive scintillation crystal bars designed to operate over the spectral range 0.2 to 10 MeV, has been constructed in the laboratory. A series of experimental images has been generated using a scaled down flight pattern mask in conjunction with a diverging gamma-ray beam. Point and extended sources have been imaged in order to assess quantitatively the performance of the system.

Gamma-ray Background Spectrum and Annihilation Rate in the Baryon-symmetric Big-bang Cosmology

NASA Technical Reports Server (NTRS)

Puget, J. L.

1973-01-01

An attempt was made to acquire experimental information on the problem of baryon symmetry on a large cosmological scale by observing the annihilation products. Data cover absorption cross sections and background radiation due to other sources for the two main products of annihilation, gamma rays and neutrinos. Test results show that the best direct experimental test for the presence of large scale antimatter lies in the gamma ray background spectrum between 1 and 70 MeV.

X-ray fluorescence beamline at the LNLS: Current instrumentation and future developments (abstract)

NASA Astrophysics Data System (ADS)

Pérez, C. A.; Bueno, M. I. S.; Neuenshwander, R. T.; Sánchez, H. J.; Tolentino, H.

2002-03-01

The x-ray fluorescence (XRF) beamline, constructed at the Brazilian National Synchrotron Radiation Laboratory (LNLS-http://www.lnls.br), has been operating for the external users since August of 1998 (C. A. Pérez et al., Proc. of the European Conference on Energy Dispersive X-Ray Spectrometry, Bologna, Italy, 1998, pp. 125-129). The synchrotron source for this beamline is the D09B (15°) dipole magnet of the LNLS storage ring. Two main experimental setups are mounted at the XRF beamline. One consists of a high vacuum chamber adapted to carry out experiments in grazing excitation conditions. This allows chemical trace and ultratrace element determination on several samples, mainly coming from environmental and biological sciences. Another setup consists of an experimental station, operated in air, in which x-ray fluorescence analysis with spatial resolution can be done. This station is equipped with a fine conical capillary, capable of achieving 20 μm spatial resolution, and with an optical microscope in order to select the region of interest on the sample surface. In this work, the main characteristic of the beamline, experimental stations as well as the description of some new experimental facilities will be given. Future development in the instrumentation focuses on an appropriate x-ray optic to be able to carry out chemical trace analysis of light elements using the total x-ray fluorescence technique. Also, chemical mapping below 10 μm spatial resolution, while keeping high flux of photon on the sample, will be achieved by using the Kirkpatrick-Baez x-ray microfocusing optic.

U.S. Government Funding for Science and Technology Cooperation with Russia

DTIC Science & Technology

2002-01-01

and Vietnamese scientists to study and understand the origin of cosmic rays , and "* collaboration among U.S., Russian, Ukrainian, and Lithuanian...International Space Station; for solar terrestrial surface radiation over the Arctic basin; and to index and track Russian biomedical articles and...experimentation on an electric propulsion thruster for small, low-power satellites "• calibrating data analysis from the Stellar X- Ray Polarimeter of

Insights into the mechanism of X-ray-induced disulfide-bond cleavage in lysozyme crystals based on EPR, optical absorption and X-ray diffraction studies

PubMed Central

Sutton, Kristin A.; Black, Paul J.; Mercer, Kermit R.; Garman, Elspeth F.; Owen, Robin L.; Snell, Edward H.; Bernhard, William A.

2013-01-01

Electron paramagnetic resonance (EPR) and online UV–visible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UV–visible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5–0.8 MGy, in contrast to the saturating dose of ∼0.2 MGy observed using EPR at much lower dose rates. The observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure. PMID:24311579

Analysis of eight argonne premium coal samples by X-ray fluorescence spectrometry

USGS Publications Warehouse

Evans, J.R.; Sellers, G.A.; Johnson, R.G.; Vivit, D.V.; Kent, J.

1990-01-01

X-ray fluorescence spectrometric methods were used in the analysis of eight Argonne Premium Coal Samples. Trace elements (Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, La, and Ce) in coal ash were determined by energy-dispersive X-ray fluorescence spectrometry; major elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, Mn, and Fe) in coal ash and trace elements (Cl and P) in whole coal were determined by wavelength-dispersive X-ray fluorescence spectrometry. The results of this study will be used in a geochemical database compiled for these materials from various analytical techniques. The experimental XRF methods and procedures used to determine these major and trace elements are described.

Verification technology of remote sensing camera satellite imaging simulation based on ray tracing

NASA Astrophysics Data System (ADS)

Gu, Qiongqiong; Chen, Xiaomei; Yang, Deyun

2017-08-01

Remote sensing satellite camera imaging simulation technology is broadly used to evaluate the satellite imaging quality and to test the data application system. But the simulation precision is hard to examine. In this paper, we propose an experimental simulation verification method, which is based on the test parameter variation comparison. According to the simulation model based on ray-tracing, the experiment is to verify the model precision by changing the types of devices, which are corresponding the parameters of the model. The experimental results show that the similarity between the imaging model based on ray tracing and the experimental image is 91.4%, which can simulate the remote sensing satellite imaging system very well.

Radiation carcinogenesis and acute radiation mortality in the rat as produced by 2.2 GeV protons

NASA Technical Reports Server (NTRS)

Shellabarger, C. J.; Straub, R. F.; Jesseph, J. E.; Montour, J. L.

1972-01-01

Biological studies, proton carcinogenesis, the interaction of protons and gamma-rays on carcinogenesis, proton-induced acute mortality, and chemical protection against proton-induced acute mortality were studied in the rat and these proton-produced responses were compared to similar responses produced by gamma-rays or X-rays. Litter-mate mice were assigned to each experimental and control group so that approximately equal numbers of litter mates were placed in each group. Animals to be studied for mammary neoplasia were handled for 365 days post-exposure when all animals alive were killed. All animals were examined frequently for mammary tumors and as these were found, they were removed, sectioned and given a pathologic classification.

Experimental demonstration of laser to x-ray conversion enhancements with low density gold targets

DOE PAGES

Shang, Wanli; Yang, Jiamin; Zhang, Wenhai; ...

2016-02-12

The enhancement of laser to x-ray conversion efficiencies using low density gold targets [W. L. Shang, J. M. Yang, and Y. S. Dong, Appl. Phys. Lett. 102, 094105 (2013)] is demonstrated. Laser to x-ray conversion efficiencies with 6.3% and 12% increases are achieved with target densities of 1 and 0.25 g/cm 3, when compared with that of a solid gold target (19.3 g/cm 3). Experimental data and numerical simulations are in good agreement. Lastly, the enhancement is caused by larger x-ray emission zone lengths formed in low density targets, which is in agreement with the simulation results.

Experimental demonstration of laser to x-ray conversion enhancements with low density gold targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shang, Wanli; Yang, Jiamin; Zhang, Wenhai

The enhancement of laser to x-ray conversion efficiencies using low density gold targets [W. L. Shang, J. M. Yang, and Y. S. Dong, Appl. Phys. Lett. 102, 094105 (2013)] is demonstrated. Laser to x-ray conversion efficiencies with 6.3% and 12% increases are achieved with target densities of 1 and 0.25 g/cm 3, when compared with that of a solid gold target (19.3 g/cm 3). Experimental data and numerical simulations are in good agreement. Lastly, the enhancement is caused by larger x-ray emission zone lengths formed in low density targets, which is in agreement with the simulation results.

Directional x-ray dark-field imaging of strongly ordered systems

NASA Astrophysics Data System (ADS)

Jensen, Torben Haugaard; Bech, Martin; Zanette, Irene; Weitkamp, Timm; David, Christian; Deyhle, Hans; Rutishauser, Simon; Reznikova, Elena; Mohr, Jürgen; Feidenhans'L, Robert; Pfeiffer, Franz

2010-12-01

Recently a novel grating based x-ray imaging approach called directional x-ray dark-field imaging was introduced. Directional x-ray dark-field imaging yields information about the local texture of structures smaller than the pixel size of the imaging system. In this work we extend the theoretical description and data processing schemes for directional dark-field imaging to strongly scattering systems, which could not be described previously. We develop a simple scattering model to account for these recent observations and subsequently demonstrate the model using experimental data. The experimental data includes directional dark-field images of polypropylene fibers and a human tooth slice.

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

PubMed Central

Manohar, Nivedh; Jones, Bernard L.; Cho, Sang Hyun

2014-01-01

Purpose: To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). Methods: A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Results: Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the investigated range of 81–100 keV, increased the FSDR up to a factor of 20, compared to 1 mm Pb, and further facilitated separation of gold XRF peaks from the scatter background. Conclusions: A detailed MC model of an experimental benchtop XFCT system has been developed and validated. In exemplary calculations to illustrate the usefulness of this model, it was shown that potential use of quasimonochromatic spectra or judicious choice of filter material/thickness to tailor the spectrum of a polychromatic x-ray source can significantly improve the performance of benchtop XFCT, while considering trade-offs between FSDR and FNST. As demonstrated, the current MC model is a reliable and powerful computational tool that can greatly expedite the further development of a benchtop XFCT system for routine preclinical molecular imaging with GNPs and other metal probes. PMID:25281958

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

PubMed

Manohar, Nivedh; Jones, Bernard L; Cho, Sang Hyun

2014-10-01

To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the investigated range of 81-100 keV, increased the FSDR up to a factor of 20, compared to 1 mm Pb, and further facilitated separation of gold XRF peaks from the scatter background. A detailed MC model of an experimental benchtop XFCT system has been developed and validated. In exemplary calculations to illustrate the usefulness of this model, it was shown that potential use of quasimonochromatic spectra or judicious choice of filter material/thickness to tailor the spectrum of a polychromatic x-ray source can significantly improve the performance of benchtop XFCT, while considering trade-offs between FSDR and FNST. As demonstrated, the current MC model is a reliable and powerful computational tool that can greatly expedite the further development of a benchtop XFCT system for routine preclinical molecular imaging with GNPs and other metal probes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Michael K; Parish, Chad M

Helium accumulation negatively impacts structural materials used in neutron-irradiated environments, such as fission and fusion reactors. Next-generation fission and fusion reactors will require structural materials, such as steels, resistant to large neutron doses yet see service temperatures in the range most affected by helium embrittlement. Previous work has indicated the difficulty of experimentally differentiating nanometer-sized helium bubbles from the Ti-Y-O rich nanoclustsers (NCs) in radiation-tolerant nanostructured ferritic alloys (NFAs). Because the NCs are expected to sequester helium away from grain boundaries and reduce embrittlement, experimental methods to study simultaneously the NC and bubble populations are needed. In this study, aberration-correctedmore » scanning transmission electron microscopy (STEM) results combining high-collection-efficiency X-ray spectrum images (SIs), multivariate statistical analysis (MVSA), and Fresnel-contrast bright-field STEM imaging have been used for such a purpose. Results indicate that Fresnel-contrast imaging, with careful attention to TEM-STEM reciprocity, differentiates bubbles from NCs, and MVSA of X-ray SIs unambiguously identifies NCs. Therefore, combined Fresnel-contrast STEM and X-ray SI is an effective STEM-based method to characterize helium-bearing NFAs.« less

An experimental system for high temperature X-ray diffraction studies with in situ mechanical loading

PubMed Central

Oswald, Benjamin B.; Schuren, Jay C.; Pagan, Darren C.; Miller, Matthew P.

2013-01-01

An experimental system with in situ thermomechanical loading has been developed to enable high energy synchrotron x-ray diffraction studies of crystalline materials. The system applies and maintains loads of up to 2250 N in uniaxial tension or compression at a frequency of up to 100 Hz. The furnace heats the specimen uniformly up to a maximum temperature of 1200 °C in a variety of atmospheres (oxidizing, inert, reducing) that, combined with in situ mechanical loading, can be used to mimic processing and operating conditions of engineering components. The loaded specimen is reoriented with respect to the incident beam of x-rays using two rotational axes to increase the number of crystal orientations interrogated. The system was used at the Cornell High Energy Synchrotron Source to conduct experiments on single crystal silicon and polycrystalline Low Solvus High Refractory nickel-based superalloy. The data from these experiments provide new insights into how stresses evolve at the crystal scale during thermomechanical loading and complement the development of high-fidelity material models. PMID:23556825

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazuritskiy, M. I., E-mail: mazurmik@gmail.com; Lerer, A. M.; Makhno, P. V.

The angular distribution of the X-ray intensity at the exit of microchannel plates at grazing incidence of monochromatic radiation on the walls of microcapillaries has been investigated. The angles and energies of the primary radiation quanta at which the synchrotron beam excites X-ray fluorescence propagating inside polycapillary structures have been determined. The angular dependences of the intensity distribution of X-rays transmitted through the microcapillaries have been studied theoretically and experimentally for energies corresponding to the region of anomalous dispersion near the L{sub 2,3} absorption edges of silicon. The propagation of waves in hollow polycapillary waveguides, the excitation of X-ray fluorescence,more » and the X-ray diffraction at the exit of microchannel plates have been modeled mathematically. The mathematical model takes into account the presence of a transition layer on the microchannel surface.« less

Procedures for cryogenic X-ray ptychographic imaging of biological samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yusuf, M.; Zhang, F.; Chen, B.

Biological sample-preparation procedures have been developed for imaging human chromosomes under cryogenic conditions. A new experimental setup, developed for imaging frozen samples using beamline I13 at Diamond Light Source, is described. This paper describes the equipment and experimental procedures as well as the authors' first ptychographic reconstructions using X-rays.

INSTRUMENTS AND METHODS OF INVESTIGATION Charge spectrum of galactic cosmic ray nuclei as measured in meteorite olivines

NASA Astrophysics Data System (ADS)

Aleksandrov, Andrei B.; Bagulya, Aleksandr V.; Vladimirov, Mikhail S.; Goncharova, Lyudmila A.; Ivliev, Aleksandr I.; Kalinina, Galina V.; Kashkarov, Leonid L.; Konovalova, Nina S.; Okat'eva, Natal'ya M.; Polukhina, Natal'ya G.; Rusetskii, Aleksei S.; Starkov, Nikolai I.

2010-11-01

This paper presents experimental results on galactic cosmic ray nuclei in olivine crystals from the Marjalahti and Eagle Station pallasites. The charge spectrum of the nuclei is measured to be in good agreement with the experimental data from the HEAO-3 and ARIEL-6 satellite missions.

Procedures for cryogenic X-ray ptychographic imaging of biological samples

DOE PAGES

Yusuf, M.; Zhang, F.; Chen, B.; ...

2017-01-12

Biological sample-preparation procedures have been developed for imaging human chromosomes under cryogenic conditions. A new experimental setup, developed for imaging frozen samples using beamline I13 at Diamond Light Source, is described. This paper describes the equipment and experimental procedures as well as the authors' first ptychographic reconstructions using X-rays.

Adaptive x-ray threat detection using sequential hypotheses testing with fan-beam experimental data (Conference Presentation)

NASA Astrophysics Data System (ADS)

Thamvichai, Ratchaneekorn; Huang, Liang-Chih; Ashok, Amit; Gong, Qian; Coccarelli, David; Greenberg, Joel A.; Gehm, Michael E.; Neifeld, Mark A.

2017-05-01

We employ an adaptive measurement system, based on sequential hypotheses testing (SHT) framework, for detecting material-based threats using experimental data acquired on an X-ray experimental testbed system. This testbed employs 45-degree fan-beam geometry and 15 views over a 180-degree span to generate energy sensitive X-ray projection data. Using this testbed system, we acquire multiple view projection data for 200 bags. We consider an adaptive measurement design where the X-ray projection measurements are acquired in a sequential manner and the adaptation occurs through the choice of the optimal "next" source/view system parameter. Our analysis of such an adaptive measurement design using the experimental data demonstrates a 3x-7x reduction in the probability of error relative to a static measurement design. Here the static measurement design refers to the operational system baseline that corresponds to a sequential measurement using all the available sources/views. We also show that by using adaptive measurements it is possible to reduce the number of sources/views by nearly 50% compared a system that relies on static measurements.

LBL Whole Frog Project

Science.gov Websites

specimens), X-ray CT imaging (industrial imaging of non-biological objects), and direct generation from experimental study unit for biology was developed with the assistance of several high school teachers, and

Experimental validation of calculated atomic charges in ionic liquids

NASA Astrophysics Data System (ADS)

Fogarty, Richard M.; Matthews, Richard P.; Ashworth, Claire R.; Brandt-Talbot, Agnieszka; Palgrave, Robert G.; Bourne, Richard A.; Vander Hoogerstraete, Tom; Hunt, Patricia A.; Lovelock, Kevin R. J.

2018-05-01

A combination of X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure spectroscopy has been used to provide an experimental measure of nitrogen atomic charges in nine ionic liquids (ILs). These experimental results are used to validate charges calculated with three computational methods: charges from electrostatic potentials using a grid-based method (ChelpG), natural bond orbital population analysis, and the atoms in molecules approach. By combining these results with those from a previous study on sulfur, we find that ChelpG charges provide the best description of the charge distribution in ILs. However, we find that ChelpG charges can lead to significant conformational dependence and therefore advise that small differences in ChelpG charges (<0.3 e) should be interpreted with care. We use these validated charges to provide physical insight into nitrogen atomic charges for the ILs probed.

CT imaging with a mobile C-arm prototype

NASA Astrophysics Data System (ADS)

Cheryauka, Arvi; Tubbs, David; Langille, Vinton; Kalya, Prabhanjana; Smith, Brady; Cherone, Rocco

2008-03-01

Mobile X-ray imagery is an omnipresent tool in conventional musculoskeletal and soft tissue applications. The next generation of mobile C-arm systems can provide clinicians of minimally-invasive surgery and pain management procedures with both real-time high-resolution fluoroscopy and intra-operative CT imaging modalities. In this study, we research two C-arm CT experimental system configurations and evaluate their imaging capabilities. In a non-destructive evaluation configuration, the X-ray Tube - Detector assembly is stationary while an imaging object is placed on a rotating table. In a medical imaging configuration, the C-arm gantry moves around the patient and the table. In our research setting, we connect the participating devices through a Mobile X-Ray Imaging Environment known as MOXIE. MOXIE is a set of software applications for internal research at GE Healthcare - Surgery and used to examine imaging performance of experimental systems. Anthropomorphic phantom volume renderings and orthogonal slices of reconstructed images are obtained and displayed. The experimental C-arm CT results show CT-like image quality that may be suitable for interventional procedures, real-time data management, and, therefore, have great potential for effective use on the clinical floor.

Constraining the rp-process by measuring 23Al(d,n)24Si with GRETINA and LENDA at NSCL

NASA Astrophysics Data System (ADS)

Wolf, Clemens; Langer, Christoph; Montes, Fernando; Pereira, Jorge; Ahn, Sunghoon; Ayoub, Sara; Bazin, Daniel; Bender, Peter; Brown, Alex; Browne, Justin; Crawford, Heather; Deleeuw, Eric; Elman, Brandon; Fiebiger, Stefan; Gade, Alexandra; Gastis, Panagiotis; Lipschutz, Samuel; Longfellow, Brenden; Nunes, Filomena; Ong, Wei-Jia; Poxon-Pearson, Terri; Perdikakis, Georgios; Reifarth, René; Schatz, Hendrik; Schmidt, Konrad; Schmitt, Jaclyn; Sullivan, Chris; Titus, Rachel; Weisshaar, Dirk; Woods, Philip; Zamora, Juan Carlos; G. T. Zegers, Remco

2018-01-01

The 23Al(p, γ)24Si stellar reaction rate has a significant impact on the light-curve emitted in X-ray bursts. Theoretical calculations show that the reaction rate is mainly determined by the properties of direct capture as well as low-lying 2+ states and a possible 4+ state in 24Si. Currently, there is little experimental information on the properties of these states. In this proceeding we will present a new experimental study to investigate this reaction, using the surrogate reaction 23Al(d,n) at 47 AMeV at the National Superconducting Cyclotron Laboratory (NSCL). We will discuss our new experimental setup which allows us to use full kinematics employing the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) to detect the γ-rays following the de-excitation of excited states of the reaction products and the Low Energy Neutron Detector Array (LENDA) to detect the recoiling neutrons. The S800 was used for identification of the 24Si recoils. As a proof of principle to show the feasibility of this concept the Q-value spectrum of 22Mg(d,n)23Al is reconstructed.

An experimental and theoretical study of the dark current and x-ray sensitivity of amorphous selenium x-ray photoconductors

NASA Astrophysics Data System (ADS)

Frey, Joel Brandon

Recently, the world of diagnostic radiography has seen the integration of digital flat panel x-ray image detectors into x-ray imaging systems, replacing analog film screens. These flat panel x-ray imagers (FPXIs) have been shown to produce high quality x-ray images and provide many advantages that are inherent to a fully digital technology. Direct conversion FPXIs based on a photoconductive layer of stabilized amorphous selenium (a-Se) have been commercialized and have proven particularly effective in the field of mammography. In the operation of these detectors, incident x-ray photons are converted directly to charge carriers in the a-Se layer and drifted to electrodes on either side of the layer by a large applied field (10 V/microm). The applied field causes a dark current to flow which is not due to the incident radiation and this becomes a source of noise which can reduce the dynamic range of the detector. The level of dark current in commercialized detectors has been reduced by the deposition of thin n- and p- type blocking layers between the electrodes and the bulk of the a-Se. Despite recent research into the dark current in metal/a-Se/metal sandwich structures, much is still unknown about the true cause and nature of this phenomenon. The work in this Ph.D. thesis describes an experimental and theoretical study of the dark current in these structures. Experiments have been performed on five separate sets of a-Se samples which approximate the photoconductive layer in an FPXI. The dark current has been measured as a function of time, sample structure, applied field, sample thickness and contact metal used. This work has conclusively shown that the dark current is almost entirely due to the injection of charge carriers from the contacts and the contribution of Poole-Frenkel enhanced bulk thermal generation is negligible. There is also evidence that while the dark current is initially controlled by the injection of holes from the positive contact, several minutes after the application of the bias, the dark current due to hole injection may decay to the point where the electron current becomes significant and even dominant. These conclusions are supported by numerical calculations of the dark current transients which have been calibrated to match experimental results. Work detailed in this Ph.D. thesis also focuses on Monte Carlo modeling of the x-ray sensitivity of a-Se FPXIs. The higher the x-ray sensitivity of a detector, the lower the radiation dose required to acquire an acceptable image. FPXIs can experience a decrease in the x-ray sensitivity of the photoconductive layer with accumulating exposure, leading to a phenomenon known as "ghosting". Modeling this decrease in sensitivity can uncover the reasons behind it. The Monte Carlo model described in this thesis is a continuation of a previous model which now considers the effects of the n- and p-like blocking layers and the flow of dark current between x-ray exposures. The simulation results explain how deep trapping of photogenerated charge carriers, and the resulting effect on the electric field distribution, contribute to sensitivity loss. The model has shown excellent agreement with experimental data and has accurately predicted a sensitivity recovery once exposure has ceased which is due to primarily to the relaxation of metastable x-ray-induced carrier trap states.

Analytical Model for Estimating the Zenith Angle Dependence of Terrestrial Cosmic Ray Fluxes

PubMed Central

Sato, Tatsuhiko

2016-01-01

A new model called “PHITS-based Analytical Radiation Model in the Atmosphere (PARMA) version 4.0” was developed to facilitate instantaneous estimation of not only omnidirectional but also angular differential energy spectra of cosmic ray fluxes anywhere in Earth’s atmosphere at nearly any given time. It consists of its previous version, PARMA3.0, for calculating the omnidirectional fluxes and several mathematical functions proposed in this study for expressing their zenith-angle dependences. The numerical values of the parameters used in these functions were fitted to reproduce the results of the extensive air shower simulation performed by Particle and Heavy Ion Transport code System (PHITS). The angular distributions of ground-level muons at large zenith angles were specially determined by introducing an optional function developed on the basis of experimental data. The accuracy of PARMA4.0 was closely verified using multiple sets of experimental data obtained under various global conditions. This extension enlarges the model’s applicability to more areas of research, including design of cosmic-ray detectors, muon radiography, soil moisture monitoring, and cosmic-ray shielding calculation. PARMA4.0 is available freely and is easy to use, as implemented in the open-access EXcel-based Program for Calculating Atmospheric Cosmic-ray Spectrum (EXPACS). PMID:27490175

Analytical Model for Estimating the Zenith Angle Dependence of Terrestrial Cosmic Ray Fluxes.

PubMed

Sato, Tatsuhiko

2016-01-01

A new model called "PHITS-based Analytical Radiation Model in the Atmosphere (PARMA) version 4.0" was developed to facilitate instantaneous estimation of not only omnidirectional but also angular differential energy spectra of cosmic ray fluxes anywhere in Earth's atmosphere at nearly any given time. It consists of its previous version, PARMA3.0, for calculating the omnidirectional fluxes and several mathematical functions proposed in this study for expressing their zenith-angle dependences. The numerical values of the parameters used in these functions were fitted to reproduce the results of the extensive air shower simulation performed by Particle and Heavy Ion Transport code System (PHITS). The angular distributions of ground-level muons at large zenith angles were specially determined by introducing an optional function developed on the basis of experimental data. The accuracy of PARMA4.0 was closely verified using multiple sets of experimental data obtained under various global conditions. This extension enlarges the model's applicability to more areas of research, including design of cosmic-ray detectors, muon radiography, soil moisture monitoring, and cosmic-ray shielding calculation. PARMA4.0 is available freely and is easy to use, as implemented in the open-access EXcel-based Program for Calculating Atmospheric Cosmic-ray Spectrum (EXPACS).

X-Ray Spectrometer For ROSAT II (SPECTROSAT)

NASA Astrophysics Data System (ADS)

Predehl, Peter; Brauninger, Heinrich

1986-01-01

The objective transmission grating was one of the earliest inventions in the field of X-ray astronomy and has been incorporated into Skylab, HERO-P, and EXOTAT. In recent years there have been advances in grating technology and spectrometer design. A high precision mechanical ruling and replication process for manufacturing large self-supporting transmission gratings has been developed by an industrial manufacturer in cooperation with the Max-Planck-Institute (MPI). Theoretical analyses have determined the optimum configuration of the grating facets and the grating surface in order to correct third order aberations and obtain maximum resolving power. We have verified experimentally that the predicted efficiencies may be achieved. In addition, an experimental study of large grating assemblies for space telescopes was made in industry with scientific guidance by MPI. Main objectives of this study were the determination of mechanical loads during launch, as well as the design, construction and fabrication of a representative model of a ROSAT grating ring. Performancy studies including instrument pro-perties as well as the simulated radiation from hot plasmas have shown the ability of SPECTROSAT to perform high efficiency, high resolution line-spectroscopy on a wide variety of cosmic X-ray sources.

Computational Insights into the O2-evolving complex of photosystem II

PubMed Central

Sproviero, Eduardo M.; McEvoy, James P.; Gascón, José A.; Brudvig, Gary W.; Batista, Victor S.

2009-01-01

Mechanistic investigations of the water-splitting reaction of the oxygen-evolving complex (OEC) of photosystem II (PSII) are fundamentally informed by structural studies. Many physical techniques have provided important insights into the OEC structure and function, including X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy as well as mass spectrometry (MS), electron paramagnetic resonance (EPR) spectroscopy and Fourier transform infrared spectroscopy applied in conjunction with mutagenesis studies. However, experimental studies have yet to yield consensus as to the exact configuration of the catalytic metal cluster and its ligation scheme. Computational modeling studies, including density functional (DFT) theory combined with quantum mechanics/molecular mechanics (QM/MM) hybrid methods for explicitly including the influence of the surrounding protein, have proposed chemically satisfactory models of the fully ligated OEC within PSII that are maximally consistent with experimental results. The inorganic core of these models is similar to the crystallographic model upon which they were based but comprises important modifications due to structural refinement, hydration and proteinaceous ligation which improve agreement with a wide range of experimental data. The computational models are useful for rationalizing spectroscopic and crystallographic results and for building a complete structure-based mechanism of water-splitting in PSII as described by the intermediate oxidation states of the OEC. This review summarizes these recent advances in QM/MM modeling of PSII within the context of recent experimental studies. PMID:18483777

Simulations of x-ray speckle-based dark-field and phase-contrast imaging with a polychromatic beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zdora, Marie-Christine, E-mail: marie-christine.zdora@diamond.ac.uk; Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE; Department of Physics & Astronomy, University College London, London WC1E 6BT

2015-09-21

Following the first experimental demonstration of x-ray speckle-based multimodal imaging using a polychromatic beam [I. Zanette et al., Phys. Rev. Lett. 112(25), 253903 (2014)], we present a simulation study on the effects of a polychromatic x-ray spectrum on the performance of this technique. We observe that the contrast of the near-field speckles is only mildly influenced by the bandwidth of the energy spectrum. Moreover, using a homogeneous object with simple geometry, we characterize the beam hardening artifacts in the reconstructed transmission and refraction angle images, and we describe how the beam hardening also affects the dark-field signal provided by specklemore » tracking. This study is particularly important for further implementations and developments of coherent speckle-based techniques at laboratory x-ray sources.« less

Electromagnetic radiation screening of microcircuits for long life applications

NASA Technical Reports Server (NTRS)

Brammer, W. G.; Erickson, J. J.; Levy, M. E.

1974-01-01

The utility of X-rays as a stimulus for screening high reliability semiconductor microcircuits was studied. The theory of the interaction of X-rays with semiconductor materials and devices was considered. Experimental measurements of photovoltages, photocurrents, and effects on specified parameters were made on discrete devices and on microcircuits. The test specimens included discrete devices with certain types of identified flaws and symptoms of flaws, and microcircuits exhibiting deviant electrical behavior. With a necessarily limited sample of test specimens, no useful correlation could be found between the X-ray-induced electrical response and the known or suspected presence of flaws.

A preliminary design study for a cosmic X-ray spectrometer

NASA Technical Reports Server (NTRS)

1972-01-01

The results are described of theoretical and experimental investigations aimed at the development of a curved crystal cosmic X-ray spectrometer to be used at the focal plane of the large orbiting X-ray telescope on the third High Energy Astronomical Observatory. The effort was concentrated on the development of spectrometer concepts and their evaluation by theoretical analysis, computer simulation, and laboratory testing with breadboard arrangements of crystals and detectors. In addition, a computer-controlled facility for precision testing and evaluation of crystals in air and vacuum was constructed. A summary of research objectives and results is included.

Future space experiments on cosmic rays and radiation on Russian segments of ISS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Panasyuk, Mikhail; Galper, Arkady; Stozhov, Yurii

1999-01-22

The report presents a survey of the Russian space program in the field of radiation and cosmic ray studies. The experimental projects were developed by scientists of different Russian Institutes and are intended for implementation on the future ISS. All the projects mentioned in this report have undergone various expertise stages in the Space Council of the Russian Science Academy ('Cosmic Ray Physics' section); the International Science-Technology Center of the Rocket-Space Corporation 'Energia' ('Astrophysics and radiation Measurements' section); Committee on Science-Technical Co-operation of the Russian Space Agency.

Resonant inelastic x-ray scattering on iso-C₂H₂Cl₂ around the chlorine K-edge: structural and dynamical aspects.

PubMed

Kawerk, Elie; Carniato, Stéphane; Journel, Loïc; Marchenko, Tatiana; Piancastelli, Maria Novella; Žitnik, Matjaž; Bučar, Klemen; Bohnic, Rok; Kavčič, Matjaž; Céolin, Denis; Khoury, Antonio; Simon, Marc

2014-10-14

We report a theoretical and experimental study of the high resolution resonant K(α) X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the K(α) emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state.

Resonant inelastic x-ray scattering on iso-C2H2Cl2 around the chlorine K-edge: Structural and dynamical aspects

NASA Astrophysics Data System (ADS)

Kawerk, Elie; Carniato, Stéphane; Journel, Loïc; Marchenko, Tatiana; Piancastelli, Maria Novella; Žitnik, Matjaž; Bučar, Klemen; Bohnic, Rok; Kavčič, Matjaž; Céolin, Denis; Khoury, Antonio; Simon, Marc

2014-10-01

We report a theoretical and experimental study of the high resolution resonant Kα X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the Kα emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state.

Soft X-ray imaging of thick carbon-based materials using the normal incidence multilayer optics.

PubMed

Artyukov, I A; Feschenko, R M; Vinogradov, A V; Bugayev, Ye A; Devizenko, O Y; Kondratenko, V V; Kasyanov, Yu S; Hatano, T; Yamamoto, M; Saveliev, S V

2010-10-01

The high transparency of carbon-containing materials in the spectral region of "carbon window" (lambda approximately 4.5-5nm) introduces new opportunities for various soft X-ray microscopy applications. The development of efficient multilayer coated X-ray optics operating at the wavelengths of about 4.5nm has stimulated a series of our imaging experiments to study thick biological and synthetic objects. Our experimental set-up consisted of a laser plasma X-ray source generated with the 2nd harmonics of Nd-glass laser, scandium-based thin-film filters, Co/C multilayer mirror and X-ray film UF-4. All soft X-ray images were produced with a single nanosecond exposure and demonstrated appropriate absorption contrast and detector-limited spatial resolution. A special attention was paid to the 3D imaging of thick low-density foam materials to be used in design of laser fusion targets.

X-Ray-induced Deuterium Enrichment of N-rich Organics in Protoplanetary Disks: An Experimental Investigation Using Synchrotron Light

NASA Astrophysics Data System (ADS)

Gavilan, Lisseth; Remusat, Laurent; Roskosz, Mathieu; Popescu, Horia; Jaouen, Nicolas; Sandt, Christophe; Jäger, Cornelia; Henning, Thomas; Simionovici, Alexandre; Lemaire, Jean Louis; Mangin, Denis; Carrasco, Nathalie

2017-05-01

The deuterium enrichment of organics in the interstellar medium, protoplanetary disks, and meteorites has been proposed to be the result of ionizing radiation. The goal of this study is to simulate and quantify the effects of soft X-rays (0.1-2 keV), an important component of stellar radiation fields illuminating protoplanetary disks, on the refractory organics present in the disks. We prepared tholins, nitrogen-rich organic analogs to solids found in several astrophysical environments, e.g., Titan’s atmosphere, cometary surfaces, and protoplanetary disks, via plasma deposition. Controlled irradiation experiments with soft X-rays at 0.5 and 1.3 keV were performed at the SEXTANTS beamline of the SOLEIL synchrotron, and were immediately followed by ex-situ infrared, Raman, and isotopic diagnostics. Infrared spectroscopy revealed the preferential loss of singly bonded groups (N-H, C-H, and R-N≡C) and the formation of sp3 carbon defects with signatures at ˜1250-1300 cm-1. Raman analysis revealed that, while the length of polyaromatic units is only slightly modified, the introduction of defects leads to structural amorphization. Finally, tholins were measured via secondary ion mass spectrometry to quantify the D, H, and C elemental abundances in the irradiated versus non-irradiated areas. Isotopic analysis revealed that significant D-enrichment is induced by X-ray irradiation. Our results are compared to previous experimental studies involving the thermal degradation and electron irradiation of organics. The penetration depth of soft X-rays in μm-sized tholins leads to volume rather than surface modifications: lower-energy X-rays (0.5 keV) induce a larger D-enrichment than 1.3 keV X-rays, reaching a plateau for doses larger than 5 × 1027 eV cm-3. Synchrotron fluences fall within the expected soft X-ray fluences in protoplanetary disks, and thus provide evidence of a new non-thermal pathway to deuterium fractionation of organic matter.

[Development of an experimental apparatus for energy calibration of a CdTe detector by means of diagnostic X-ray equipment].

PubMed

Fukuda, Ikuma; Hayashi, Hiroaki; Takegami, Kazuki; Konishi, Yuki

2013-09-01

Diagnostic X-ray equipment was used to develop an experimental apparatus for calibrating a CdTe detector. Powder-type samples were irradiated with collimated X-rays. On excitation of the atoms, characteristic X-rays were emitted. We prepared Nb2O5, SnO2, La2O3, Gd2O3, and WO3 metal oxide samples. Experiments using the diagnostic X-ray equipment were carried out to verify the practicality of our apparatus. First, we verified that the collimators involving the apparatus worked well. Second, the X-ray spectra were measured using the prepared samples. Finally, we analyzed the spectra, which indicated that the energy calibration curve had been obtained at an accuracy of ±0.06 keV. The developed apparatus could be used conveniently, suggesting it to be useful for the practical training of beginners and researchers.

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility.

PubMed

Fournier, K B; Brown, C G; Yeoman, M F; Fisher, J H; Seiler, S W; Hinshelwood, D; Compton, S; Holdener, F R; Kemp, G E; Newlander, C D; Gilliam, R P; Froula, N; Lilly, M; Davis, J F; Lerch, Maj A; Blue, B E

2016-11-01

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility's diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built-in calorimeters give in situ measurements of the x-ray environment along the sample lines of sight. The measured accuracy of sample responses as well as planned modifications to the XTRRA cassette is discussed.

Establishment of a New Zealand rabbit model of spinal tuberculosis.

PubMed

Geng, Guangqi; Wang, Qian; Shi, Jiandang; Yan, Junfa; Niu, Ningkui; Wang, Zili

2015-04-01

This was an experimental study. To investigate and evaluate the experimental method of establishing a New Zealand rabbit model of spinal tuberculosis. Establishing animal models of tuberculosis is critical to the experimental and clinical study of tuberculosis, especially spinal tuberculosis. However, the rapid spread of Mycobacterium tuberculosis and subsequent high mortality thwarted their effort. Since then, no animal models have been established of spinal tuberculosis. Forty-two New Zealand rabbits were randomly divided into experimental (n=20), control (n=20), and blank groups (n=2). Experimental animals were sensitized by complete Freund's adjuvant. A hole drilled under the upper endplate of the L4 vertebral body was filled with a gelfoam sponge infused with 0.1 mL H37Rv standard M. tuberculosis suspension (in controls, culture medium, and saline). Blank animals received no treatment. Survival 8 weeks after surgery was 89.5%, 94.7%, and 100% in experimental, control, and blank groups, respectively. The model was successfully established in all surviving experimental rabbits. In experimental animals, vertebral body destruction at 4 weeks was 50% by x-ray; 83.3% by computed tomography reconstruction and magnetic resonance imaging; at 8 weeks, 58.8% by x-ray and 100% by computed tomograph reconstruction and magnetic resonance imaging. At 8 weeks, experimental animals developed vertebral destruction, granulation, and necrosis and 17.6% had psoas abscess. Histopathology revealed numerous lymphocytes and epithelioid cells, trabecular bone fracture, and coagulative necrosis in the vertebrae of experimental animals; bacterium culture was 52.9% positive. Control and blank animals showed no such changes. A New Zealand rabbit of spinal tuberculosis model can be successfully established by drilling a hole in the upper endplate of the vertebral body, filling with gelfoam sponge infused with H37Rv standard M. tuberculosis suspension after sensitization by complete Freund's adjuvant.

The development of efficient X-ray conversion material for digital mammography

NASA Astrophysics Data System (ADS)

Oh, K.; Shin, J.; Kim, S.; Lee, Y.; Jeon, S.; Kim, J.; Nam, S.

2012-02-01

In this study, an experimental method based on theory is used to develop photoconductor that can replace the a-Se currently used as X-ray conversion layer in digital mammography. This is necessary because a-Se produced by the commercial fabrication method, of physical vapor deposition, has exhibited several problems when applied to digital mammography: instability due to crystallization and defect expansion due to high operating voltages, which is called the aging effect. Therefore, our work focused on developing a method of fabricating X-ray conversion films that do not suffer from crystallization and X-ray damage and optimizing the factors affecting the properties of the candidate photoconductors in order to acquire sufficient electrical signals to detect minute calcifications. The photoconductors were initially selected after the requirements for X-ray conversion materials, such as high atomic absorption, density, band-gap energy, work function, and resistivity, were examined. We selected HgI2, PbI2, and PbO because of their basic properties. Next, we experimentally investigated the performance of film samples fabricated by sedimentation and screen printing instead of physical vapor deposition. The structure of the X-ray conversion films (e.g., the thickness, electrodes, and blocking layer) were optimized for the application of a relatively low voltage to the X-ray conversion layer. The performance of the films were morphologically and electrically evaluated under mammography X-ray exposure conditions, and compared with those of a-Se films produced by physical vapor deposition. PbO appeared to be the most suitable alternative material because its electrical properties, such as the dark current, sensitivity, and signal-to-noise ratio (SNR), did not reveal the X-ray damage problem, and thus were maintained after repeated exposure to X-rays. Although PbO showed low sensitivity to X-ray exposure, its SNR was superior to that of the other materials, which is expected to improve its detective quantum efficiency, one of the factors used in evaluating images acquired by digital mammography.

X-Ray Micro-Tomography Applied to Nasa's Materials Research: Heat Shields, Parachutes and Asteroids

NASA Technical Reports Server (NTRS)

Panerai, Francesco; Borner, Arnaud; Ferguson, Joseph C.; Mansour, Nagi N.; Stern, Eric C.; Barnard, Harold S.; Macdowell, Alastair A.; Parkinson, Dilworth Y.

2017-01-01

X-ray micro-tomography is used to support the research on materials carried out at NASA Ames Research Center. The technique is applied to a variety of applications, including the ability to characterize heat shield materials for planetary entry, to study the Earth- impacting asteroids, and to improve broadcloths of spacecraft parachutes. From micro-tomography images, relevant morphological and transport properties are determined and validated against experimental data.

Microscale Electromagnetic Heating in Heterogeneous Energetic Materials Based on X-ray Computed Tomography

NASA Astrophysics Data System (ADS)

Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; Glover, B. B.; Duque, A. L. Higginbotham; Perry, W. L.; Patterson, B. M.; Dalvit, D. A. R.; Moore, D. S.

2016-04-01

Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. We analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

Theoretical modeling of a portable x-ray tube based KXRF system to measure lead in bone

PubMed Central

Specht, Aaron J; Weisskopf, Marc G; Nie, Linda Huiling

2017-01-01

Objective K-shell x-ray fluorescence (KXRF) techniques have been used to identify health effects resulting from exposure to metals for decades, but the equipment is bulky and requires significant maintenance and licensing procedures. A portable x-ray fluorescence (XRF) device was developed to overcome these disadvantages, but introduced a measurement dependency on soft tissue thickness. With recent advances to detector technology, an XRF device utilizing the advantages of both systems should be feasible. Approach In this study, we used Monte Carlo simulations to test the feasibility of an XRF device with a high-energy x-ray tube and detector operable at room temperature. Main Results We first validated the use of Monte Carlo N-particle transport code (MCNP) for x-ray tube simulations, and found good agreement between experimental and simulated results. Then, we optimized x-ray tube settings and found the detection limit of the high-energy x-ray tube based XRF device for bone lead measurements to be 6.91 μg g−1 bone mineral using a cadmium zinc telluride detector. Significance In conclusion, this study validated the use of MCNP in simulations of x-ray tube physics and XRF applications, and demonstrated the feasibility of a high-energy x-ray tube based XRF for metal exposure assessment. PMID:28169835

Theoretical modeling of a portable x-ray tube based KXRF system to measure lead in bone.

PubMed

Specht, Aaron J; Weisskopf, Marc G; Nie, Linda Huiling

2017-03-01

K-shell x-ray fluorescence (KXRF) techniques have been used to identify health effects resulting from exposure to metals for decades, but the equipment is bulky and requires significant maintenance and licensing procedures. A portable x-ray fluorescence (XRF) device was developed to overcome these disadvantages, but introduced a measurement dependency on soft tissue thickness. With recent advances to detector technology, an XRF device utilizing the advantages of both systems should be feasible. In this study, we used Monte Carlo simulations to test the feasibility of an XRF device with a high-energy x-ray tube and detector operable at room temperature. We first validated the use of Monte Carlo N-particle transport code (MCNP) for x-ray tube simulations, and found good agreement between experimental and simulated results. Then, we optimized x-ray tube settings and found the detection limit of the high-energy x-ray tube based XRF device for bone lead measurements to be 6.91 µg g -1 bone mineral using a cadmium zinc telluride detector. In conclusion, this study validated the use of MCNP in simulations of x-ray tube physics and XRF applications, and demonstrated the feasibility of a high-energy x-ray tube based XRF for metal exposure assessment.

Recent advances in continuum plasticity: phenomenological modeling and experimentation using X-ray diffraction

NASA Astrophysics Data System (ADS)

Edmiston, John Kearney

This work explores the field of continuum plasticity from two fronts. On the theory side, we establish a complete specification of a phenomenological theory of plasticity for single crystals. The model serves as an alternative to the popular crystal plasticity formulation. Such a model has been previously proposed in the literature; the new contribution made here is the constitutive framework and resulting simulations. We calibrate the model to available data and use a simple numerical method to explore resulting predictions in plane strain boundary value problems. Results show promise for further investigation of the plasticity model. Conveniently, this theory comes with a corresponding experimental tool in X-ray diffraction. Recent advances in hardware technology at synchrotron sources have led to an increased use of the technique for studies of plasticity in the bulk of materials. The method has been successful in qualitative observations of material behavior, but its use in quantitative studies seeking to extract material properties is open for investigation. Therefore in the second component of the thesis several contributions are made to synchrotron X-ray diffraction experiments, in terms of method development as well as the quantitative reporting of constitutive parameters. In the area of method development, analytical tools are developed to determine the available precision of this type of experiment—a crucial aspect to determine if the method is to be used for quantitative studies. We also extract kinematic information relating to intragranular inhomogeneity which is not accessible with traditional methods of data analysis. In the area of constitutive parameter identification, we use the method to extract parameters corresponding to the proposed formulation of plasticity for a titanium alloy (HCP) which is continuously sampled by X-ray diffraction during uniaxial extension. These results and the lessons learned from the efforts constitute early reporting of the quantitative profitability of undertaking such a line of experimentation for the study of plastic deformation processes.

{1 1 1} facet growth laws and grain competition during silicon crystallization

NASA Astrophysics Data System (ADS)

Stamelou, V.; Tsoutsouva, M. G.; Riberi-Béridot, T.; Reinhart, G.; Regula, G.; Baruchel, J.; Mangelinck-Noël, N.

2017-12-01

Directional solidification from mono-crystalline Si seeds having different orientations along the growth direction is studied. Due to the frequent twinning phenomenon, new grains soon nucleate during growth. The grain competition is then characterized in situ by imaging the dynamic evolution of the grain boundaries and of the corresponding grain boundary grooves that are formed at the solid-liquid interface. To perform this study, an experimental investigation based on Bridgman solidification technique coupled with in situ X-ray imaging is conducted in an original device: GaTSBI (Growth at high Temperature observed by X-ray Synchrotron Beam Imaging). Imaging characterisation techniques using X-ray synchrotron radiation at ESRF (European Synchrotron Radiation Facility, Grenoble, France) are applied during the solidification to study the growth dynamics. Facetted/facetted grain boundary grooves only are studied due to their importance in the grain competition because of their implication in the twinning mechanism. The maximum undercooling inside the groove is calculated from the groove depth knowing the local temperature gradient. Additionally, thanks to dynamic X-ray images, the global solid-liquid interface growth rate and the normal growth rate of the {1 1 1} facets existing at the grooves and at the edges are measured. From these measurements, experimental growth laws that correlate the normal velocity of the {1 1 1} facets with the maximum undercooling of the groove are extracted and compared to existing theoretical models. Finally, the experimental laws found for the contribution to the undercooling of the {1 1 1} facets are in good agreement with the theoretical model implying nucleation and growth eased by the presence of dislocations. Moreover, it is shown that, for the same growth parameters, the undercooling at the level of the facets (always lower than 1 K) is higher at the edges so that there is a higher probability of twin nucleation at the edges which is in agreement with the grain structure development characterised in the present experiments as well as in the literature.

Experimental demonstration of a soft x-ray self-seeded free-electron laser

DOE PAGES

Ratner, D.; Abela, R.; Amann, J.; ...

2015-02-06

The Linac Coherent Light Source has added self-seeding capability to the soft x-ray range using a grating monochromator system. We report demonstration of soft x-ray self-seeding with a measured resolving power of 2000-5000, wavelength stability of 10 -4, and an increase in peak brightness by a factor of 2-5 across the photon energy range of 500-1000 eV. By avoiding the need for a monochromator at the experimental station, the self-seeded beam can deliver as much as 50 fold higher brightness to users.

Experimental study of the rigidity and transparency to ionizing radiation of composite materials used in the enclosure under pressure of the Micromegas detector

NASA Astrophysics Data System (ADS)

Harbaoui, Imen; Besbes, Hatem; Chafra, Moez

Innovation in the field of nuclear imaging is necessarily followed by a radical change in the detection principle. The gas detector Micromegas (Mesh Micro Structure Gaseous) could be an interesting option, thanks to the stability and robustness of such a detector. Thus, it was necessary to study the implementation of the detector enclosure in composite materials. The focus of the present study was the robustness and gamma rays transparency of a set of composites. The studied composites were reinforced with vegetable fibers (alfa), and synthetic fibers. The mechanical properties of all composites specimen were evaluated by three-point bending test, whereas, gamma ray transparency was evaluated by the exposition of composites specimen to a mono-energetic gamma ray beam emitted by a Technetium 99-m source. Findings revealed that the biocomposite materials using alfa fiber and Polymethyl Methacrylate matrix are very promising as long as they present good robustness and high gamma ray transparency in diagnostic range.

Line x-ray source for diffraction enhanced imaging in clinical and industrial applications

NASA Astrophysics Data System (ADS)

Wang, Xiaoqin

Mammography is one type of imaging modalities that uses a low-dose x-ray or other radiation sources for examination of breasts. It plays a central role in early detection of breast cancers. The material similarity of tumor-cell and health cell, breast implants surgery and other factors, make the breast cancers hard to visualize and detect. Diffraction enhanced imaging (DEI), first proposed and investigated by D. Chapman is a new x-ray radiographic imaging modality using monochromatic x-rays from a synchrotron source, which produced images of thick absorbing objects that are almost completely free of scatter. It shows dramatically improved contrast over standard imaging when applied to the same phantom. The contrast is based not only on attenuation but also on the refraction and diffraction properties of the sample. This imaging method may improve image quality of mammography, other medical applications, industrial radiography for non-destructive testing and x-ray computed tomography. However, the size, and cost, of a synchrotron source limits the application of the new modality to be applicable at clinical levels. This research investigates the feasibility of a designed line x-ray source to produce intensity compatible to synchrotron sources. It is composed of a 2-cm in length tungsten filament, installed on a carbon steel filament cup (backing plate), as the cathode and a stationary oxygen-free copper anode with molybdenum coating on the front surface serves as the target. Characteristic properties of the line x-ray source were computationally studied and the prototype was experimentally investigated. SIMIION code was used to computationally study the electron trajectories emanating from the filament towards the molybdenum target. A Faraday cup on the prototype device, proof-of-principle, was used to measure the distribution of electrons on the target, which compares favorably to computational results. The intensities of characteristic x-ray for molybdenum, tungsten and rhodium targets were investigated with different window materials for -30kV to -100kV applied potential. Heat loading and thermal management of the target has been investigated computationally using COMSOL code package, and experimental measurements of target temperature rise was taken via thermocouples attached to the target. Temperature measurements for low voltage, low current regime without active cooling were compared to computational results for code-experiment benchmarking. Two different phantoms were used in the simulation of DEI images, which showed that the designed x-ray source with DEI setup could produce images with significant improved contrast. The computational results, along with experimental measurements on the prototype setup, indicate the possibility of scale up to larger area x-ray source adequate for DEI applications.

About a method for compressing x-ray computed microtomography data

NASA Astrophysics Data System (ADS)

Mancini, Lucia; Kourousias, George; Billè, Fulvio; De Carlo, Francesco; Fidler, Aleš

2018-04-01

The management of scientific data is of high importance especially for experimental techniques that produce big data volumes. Such a technique is x-ray computed tomography (CT) and its community has introduced advanced data formats which allow for better management of experimental data. Rather than the organization of the data and the associated meta-data, the main topic on this work is data compression and its applicability to experimental data collected from a synchrotron-based CT beamline at the Elettra-Sincrotrone Trieste facility (Italy) and studies images acquired from various types of samples. This study covers parallel beam geometry, but it could be easily extended to a cone-beam one. The reconstruction workflow used is the one currently in operation at the beamline. Contrary to standard image compression studies, this manuscript proposes a systematic framework and workflow for the critical examination of different compression techniques and does so by applying it to experimental data. Beyond the methodology framework, this study presents and examines the use of JPEG-XR in combination with HDF5 and TIFF formats providing insights and strategies on data compression and image quality issues that can be used and implemented at other synchrotron facilities and laboratory systems. In conclusion, projection data compression using JPEG-XR appears as a promising, efficient method to reduce data file size and thus to facilitate data handling and image reconstruction.

Two-dimensional time-resolved X-ray diffraction study of liquid/solid fraction and solid particle size in Fe-C binary system with an electrostatic levitator furnace

NASA Astrophysics Data System (ADS)

Yonemura, M.; Okada, J.; Watanabe, Y.; Ishikawa, T.; Nanao, S.; Shobu, T.; Toyokawa, H.

2013-03-01

Liquid state provides functions such as matter transport or a reaction field and plays an important role in manufacturing processes such as refining, forging or welding. However, experimental procedures are significantly difficult for an observation of solidification process of iron and iron-based alloys in order to identify rapid transformations subjected to fast temperature evolution. Therefore, in order to study the solidification in iron and iron-based alloys, we considered a combination of high energy X-ray diffraction measurements and an electrostatic levitation method (ESL). In order to analyze the liquid/solid fraction, the solidification of melted spherical specimens was measured at a time resolution of 0.1 seconds during rapid cooling using the two-dimensional time-resolved X-ray diffraction. Furthermore, the observation of particle sizes and phase identification was performed on a trial basis using X-ray small angle scattering with X-ray diffraction.

Study of Cr/Sc-based multilayer reflecting mirrors using soft x-ray reflectivity and standing wave-enhanced x-ray fluorescence

NASA Astrophysics Data System (ADS)

Wu, Meiyi; Burcklen, Catherine; André, Jean-Michel; Guen, Karine Le; Giglia, Angelo; Koshmak, Konstantin; Nannarone, Stefano; Bridou, Françoise; Meltchakov, Evgueni; Rossi, Sébastien de; Delmotte, Franck; Jonnard, Philippe

2017-11-01

We study Cr/Sc-based multilayer mirrors designed to work in the water window range using hard and soft x-ray reflectivity as well as x-ray fluorescence enhanced by standing waves. Samples differ by the elemental composition of the stack, the thickness of each layer, and the order of deposition. This paper mainly consists of two parts. In the first part, the optical performances of different Cr/Sc-based multilayers are reported, and in the second part, we extend further the characterization of the structural parameters of the multilayers, which can be extracted by comparing the experimental data with simulations. The methodology is detailed in the case of Cr/B4C/Sc sample for which a three-layer model is used. Structural parameters determined by fitting reflectivity curve are then introduced as fixed parameters to plot the x-ray standing wave curve, to compare with the experiment, and confirm the determined structure of the stack.

How Radiotherapy Was Historically Used To Treat Pneumonia: Could It Be Useful Today?

PubMed Central

Calabrese, Edward J.; Dhawan, Gaurav

2013-01-01

X-ray therapy was used to treat pneumonia during the first half of the 20th century. Fifteen studies report that approximately 700 cases of bacterial (lobar and bronchopneumonia), sulfanilamide non-responsive, interstitial, and atypical pneumonia were effectively treated by low doses of X-rays, leading to disease resolution, based on clinical symptoms, objective disease biomarkers, and mortality incidence. The capacity of the X-ray treatment to reduce mortality was similar to serum therapy and sulfonamide treatment during the same time period. Studies with four experimental animal models (i.e., mice, guinea pig, cat, and dog) with bacterial and viral pneumonia supported the clinical findings. The mechanism by which the X-ray treatment acts upon pneumonia involves the induction of an anti-inflammatory phenotype that leads to a rapid reversal of clinical symptoms, facilitating disease resolution. The capacity of low doses of X-rays to suppress inflammatory responses is a significant new concept with widespread biomedical and therapeutic applications. PMID:24348219

Wide-angle x-ray scattering and solid-state nuclear magnetic resonance data combined to test models for cellulose microfibrils in mung bean cell walls.

PubMed

Newman, Roger H; Hill, Stefan J; Harris, Philip J

2013-12-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette.

Polycapillary based μXRF station for 3D colour tomography

NASA Astrophysics Data System (ADS)

Hampai, D.; Cherepennikov, Yu. M.; Liedl, A.; Cappuccio, G.; Capitolo, E.; Iannarelli, M.; Azzutti, C.; Gladkikh, Yu. P.; Marcelli, A.; Dabagov, S. B.

2018-04-01

The "Rainbow X-Ray" (RXR) experimental station at XLab Frascati of the Frascati's National Laboratories (LNF) INFN is a dedicated station for X-ray fluorescence studies based on the use of polycapillary lenses in a confocal geometry. The flexible RXR layout allows investigating specimens of the dimensions ranging from several millimeters up to half meter and weighting up to several tens of kilograms. Compared to similar existing XRF stations, apart of the possibility for investigating large samples, the main advantage of this equipment is the detection system with two spectrometers optimized to work separately at high and at low X-ray energies. The confocal geometry combined with a 3-axes fine motion system makes possible 3D μXRF elemental tomographic acquisitions (colour tomography). At present this station in operation at high XRF energies is used for cultural heritage and geological applications. We present and discuss here the analytical performances of this experimental station pointing out the advantages in different application areas.

Development of a 3-D X-ray system

NASA Astrophysics Data System (ADS)

Evans, James Paul Owain

The interpretation of standard two-dimensional x-ray images by humans is often very difficult. This is due to the lack of visual cues to depth in an image which has been produced by transmitted radiation. The solution put forward in this research is to introduce binocular parallax, a powerful physiological depth cue, into the resultant shadowgraph x-ray image. This has been achieved by developing a binocular stereoscopic x-ray imaging technique, which can be used for both visual inspection by human observers and also for the extraction of three-dimensional co-ordinate information. The technique is implemented in the design and development of two experimental x-ray systems and also the development of measurement algorithms. The first experimental machine is based on standard linear x-ray detector arrays and was designed as an optimum configuration for visual inspection by human observers. However, it was felt that a combination of the 3-D visual inspection capability together with a measurement facility would enhance the usefulness of the technique. Therefore, both a theoretical and an empirical analysis of the co-ordinate measurement capability of the machine has been carried out. The measurement is based on close-range photogrammetric techniques. The accuracy of the measurement has been found to be of the order of 4mm in x, 3mm in y and 6mm in z. A second experimental machine was developed and based on the same technique as that used for the first machine. However, a major departure has been the introduction of a dual energy linear x-ray detector array which will allow, in general, the discrimination between organic and inorganic substances. The second design is a compromise between ease of visual inspection for human observers and optimum three-dimensional co-ordinate measurement capability. The system is part of an on going research programme into the possibility of introducing psychological depth cues into the resultant x-ray images. The research presented in this thesis was initiated to enhance the visual interpretation of complex x-ray images, specifically in response to problems encountered in the routine screening of freight by HM. Customs and Excise. This phase of the work culminated in the development of the first experimental machine. During this work the security industry was starting to adopt a new type of x-ray detector, namely the dual energy x-ray sensor. The Department of Transport made available funding to the Police Scientific Development Branch (P.S.D.B.), part of The Home Office Science and Technology Group, to investigate the possibility of utilising the dual energy sensor in a 3-D x-ray screening system. This phase of the work culminated in the development of the second experimental machine.

Gamma rays of energy or = 10(15) eV from Cyg X-3

NASA Technical Reports Server (NTRS)

Kifune, T.; Nishijima, K.; Hara, T.; Hatano, Y.; Hayashida, N.; Honda, M.; Kamata, K.; Matsubara, Y.; Mori, M.; Nagano, M.

1985-01-01

The experimental data of extensive air showers observed at Akeno have been analyzed to detect the gamma ray signal from Cyg X-3. After muon poor air showers are selected, the correlation of data acquisition time with 4.8 hours X-ray period is studied, giving the data concentration near the phase 0.6, the time of X-ray maximum. The probability that uniform backgrounds create the distribution is 0.2%. The time averaged integral gamma ray flux is estimated as (1.1 + or - 0.4)x 10 to the -14th power cm(-2) sec(-1) for Eo 10 to the 15th power eV and (8.8 + or - 5.0)x 10 to the 14th power cm(-2) sec(-1) for Eo 6 x 10 to the 14th power eV.

Talbot-Lau x-ray interferometry for high energy density plasma diagnostic.

PubMed

Stutman, D; Finkenthal, M

2011-11-01

High resolution density diagnostics are difficult in high energy density laboratory plasmas (HEDLP) experiments due to the scarcity of probes that can penetrate above solid density plasmas. Hard x-rays are one possible probe for such dense plasmas. We study the possibility of applying an x-ray method recently developed for medical imaging, differential phase-contrast with Talbot-Lau interferometers, for the diagnostic of electron density and small-scale hydrodynamic instabilities in HEDLP experiments. The Talbot method uses micro-periodic gratings to measure the refraction and ultra-small angle scatter of x-rays through an object and is attractive for HEDLP diagnostic due to its capability to work with incoherent and polychromatic x-ray sources such as the laser driven backlighters used for HEDLP radiography. Our paper studies the potential of the Talbot method for HEDLP diagnostic, its adaptation to the HEDLP environment, and its extension of high x-ray energy using micro-periodic mirrors. The analysis is illustrated with experimental results obtained using a laboratory Talbot interferometer. © 2011 American Institute of Physics

Effect of near-infrared rays on female menstrual pain in Korea.

PubMed

Lee, Jin-Min; Kim, Kye-Ha

2017-09-01

Most Korean women who experience menstrual pain have reported taking pain medicine and making use of complementary alternative therapies. However, because some interventions may cause side effects, more effective pain-relieving measures need to be identified. This study using a non-equivalent group design, evaluated the effects of near-infrared rays on dysmenorrhea among Korean women. The experimental group wore a near-infrared ray abdominal belt for the duration of one menstrual cycle until the end of the menstrual period, while the control group used hot packs. The level of menstrual pain, menstrual pain duration, and pain medicine use were measured. The menstrual pain, average menstrual pain duration, and use of analgesics were reduced in the near-infrared rays group. The results of this study indicate that the near-infrared ray LED belt was effective in reducing menstrual pain, menstrual pain duration compared to the use of analgesics in Korean women with dysmenorrhea. Therefore, near-infrared rays may be used to relieve menstrual pain and improve the quality of life of women with dysmenorrhea in Korea. © 2017 John Wiley & Sons Australia, Ltd.

Experimental evidence of charge transfer in a functionalized hexavanadate: a high resolution X-ray diffraction study.

PubMed

Xu, Xiao; Spasojević-de Biré, Anne; Ghermani, Nour Eddine; Wei, Yongge; Novaković, Sladjana; Bošnjaković-Pavlović, Nada; Wu, Pingfan

2017-07-19

A high resolution X-ray diffraction study has been carried out on [(C 4 H 9 ) 4 N] 2 [V 6 O 13 {(OCH 2 ) 3 CCH 2 OCCH 2 CH 3 } 2 ] (V6-C3) at 100 K. The V6 core possesses a negative charge, leading to a strong polarization of the anion. A nucleophilic region localized near the organic moiety and an electrophilic region in the vicinity of the V6 core provide an overall description of charge-transfer behavior.

Monte Carlo Simulation of X-Ray Spectra in Mammography and Contrast-Enhanced Digital Mammography Using the Code PENELOPE

NASA Astrophysics Data System (ADS)

Cunha, Diego M.; Tomal, Alessandra; Poletti, Martin E.

2013-04-01

In this work, the Monte Carlo (MC) code PENELOPE was employed for simulation of x-ray spectra in mammography and contrast-enhanced digital mammography (CEDM). Spectra for Mo, Rh and W anodes were obtained for tube potentials between 24-36 kV, for mammography, and between 45-49 kV, for CEDM. The spectra obtained from the simulations were analytically filtered to correspond to the anode/filter combinations usually employed in each technique (Mo/Mo, Rh/Rh and W/Rh for mammography and Mo/Cu, Rh/Cu and W/Cu for CEDM). For the Mo/Mo combination, the simulated spectra were compared with those obtained experimentally, and for spectra for the W anode, with experimental data from the literature, through comparison of distribution shape, average energies, half-value layers (HVL) and transmission curves. For all combinations evaluated, the simulated spectra were also compared with those provided by different models from the literature. Results showed that the code PENELOPE provides mammographic x-ray spectra in good agreement with those experimentally measured and those from the literature. The differences in the values of HVL ranged between 2-7%, for anode/filter combinations and tube potentials employed in mammography, and they were less than 5% for those employed in CEDM. The transmission curves for the spectra obtained also showed good agreement compared to those computed from reference spectra, with average relative differences less than 12% for mammography and CEDM. These results show that the code PENELOPE can be a useful tool to generate x-ray spectra for studies in mammography and CEDM, and also for evaluation of new x-ray tube designs and new anode materials.

Determination of minor and trace elements in kidney stones by x-ray fluorescence analysis

NASA Astrophysics Data System (ADS)

Srivastava, Anjali; Heisinger, Brianne J.; Sinha, Vaibhav; Lee, Hyong-Koo; Liu, Xin; Qu, Mingliang; Duan, Xinhui; Leng, Shuai; McCollough, Cynthia H.

2014-03-01

The determination of accurate material composition of a kidney stone is crucial for understanding the formation of the kidney stone as well as for preventive therapeutic strategies. Radiations probing instrumental activation analysis techniques are excellent tools for identification of involved materials present in the kidney stone. In particular, x-ray fluorescence (XRF) can be very useful for the determination of minor and trace materials in the kidney stone. The X-ray fluorescence measurements were performed at the Radiation Measurements and Spectroscopy Laboratory (RMSL) of department of nuclear engineering of Missouri University of Science and Technology and different kidney stones were acquired from the Mayo Clinic, Rochester, Minnesota. Presently, experimental studies in conjunction with analytical techniques were used to determine the exact composition of the kidney stone. A new type of experimental set-up was developed and utilized for XRF analysis of the kidney stone. The correlation of applied radiation source intensity, emission of X-ray spectrum from involving elements and absorption coefficient characteristics were analyzed. To verify the experimental results with analytical calculation, several sets of kidney stones were analyzed using XRF technique. The elements which were identified from this techniques are Silver (Ag), Arsenic (As), Bromine (Br), Chromium (Cr), Copper (Cu), Gallium (Ga), Germanium (Ge), Molybdenum (Mo), Niobium (Nb), Rubidium (Rb), Selenium (Se), Strontium (Sr), Yttrium (Y), Zirconium (Zr). This paper presents a new approach for exact detection of accurate material composition of kidney stone materials using XRF instrumental activation analysis technique.

Experimental and theoretical investigation of the rocking curves measured for MoK{sub α} X-ray characteristic lines in the double-crystal nondispersive scheme

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marchenkov, N. V., E-mail: marchenkov@ns.crys.ras.ru; Chukhovskii, F. N.; Blagov, A. E.

2015-03-15

The rocking curves (RCs) for MoK{sub α1} and MoK{sub α2} characteristic X-ray lines have been experimentally and theoretically studied in the nondispersive scheme of an X-ray double-crystal TPC-K diffractometer. The results of measurements and theoretical calculations of double-crystal RCs for characteristic X-rays from tubes with a molybdenum anode and different widths of slits show that a decrease in the slit width leads to an increase in the relative contribution of the MoK{sub α2}-line RC in comparison with the intensity of the tails of the MoK{sub α1}-line RC. It is shown that the second peak of the MoK{sub α2} line becomesmore » increasingly pronounced in the tail of the MoK{sub α1}-line RC with a decrease in the slit width. Two plane-parallel Si plates (input faces (110), diffraction vector h 〈220〉) were used as a monochromator crystal and a sample. The results of measuring double-crystal RCs are in good agreement with theoretical calculations.« less

Finite Element Simulation and X-Ray Microdiffraction Study of Strain Partitioning in a Layered Nanocomposite

DOE PAGES

Barabash, R. I.; Agarwal, V.; Koric, S.; ...

2016-01-01

Tmore » he depth-dependent strain partitioning across the interfaces in the growth direction of the NiAl/Cr(Mo) nanocomposite between the Cr and NiAl lamellae was directly measured experimentally and simulated using a finite element method (FEM). Depth-resolved X-ray microdiffraction demonstrated that in the as-grown state both Cr and NiAl lamellae grow along the 111 direction with the formation of as-grown distinct residual ~0.16% compressive strains for Cr lamellae and ~0.05% tensile strains for NiAl lamellae. hree-dimensional simulations were carried out using an implicit FEM. First simulation was designed to study residual strains in the composite due to cooling resulting in formation of crystals. Strains in the growth direction were computed and compared to those obtained from the microdiffraction experiments. Second simulation was conducted to understand the combined strains resulting from cooling and mechanical indentation of the composite. Numerical results in the growth direction of crystal were compared to experimental results confirming the experimentally observed trends.« less

Structural and dynamical properties of chlorinated hydrocarbons studied with resonant inelastic x-ray scattering

NASA Astrophysics Data System (ADS)

Bohinc, R.; Žitnik, M.; Bučar, K.; Kavčič, M.; Carniato, S.; Journel, L.; Guillemin, R.; Marchenko, T.; Kawerk, E.; Simon, M.; Cao, W.

2016-04-01

We present a theoretical and experimental study of resonant inelastic x-ray scattering on a large group of chlorinated hydrocarbons: CH3Cl, CH2Cl2, CHCl3, CCl4, CH3CH2Cl, ClCH2CH2Cl, CH3CHCl2, CH3CCl3, C2H2Cl2-iso, C2H2Cl2-cis, C2H2Cl2-trans, and C6H5Cl. Differences in structural and dynamical properties of the molecules generated by diverse chemical environments are observed in the measured Cl(Kα) spectral maps as well as in the Cl(K) total fluorescence yield spectra. The energy position, relative intensity, and the width of the Franck-Condon distribution of low-lying σ∗ and π∗ resonances are extracted by a fitting procedure taking into account the experimental broadening. The theoretical values obtained with the transition potential and Δ Kohn-Sham methods are in good agreement with the experimental parameters indicating subtle differences due to variations in the molecular structure.

Structural and dynamical properties of chlorinated hydrocarbons studied with resonant inelastic x-ray scattering.

PubMed

Bohinc, R; Žitnik, M; Bučar, K; Kavčič, M; Carniato, S; Journel, L; Guillemin, R; Marchenko, T; Kawerk, E; Simon, M; Cao, W

2016-04-07

We present a theoretical and experimental study of resonant inelastic x-ray scattering on a large group of chlorinated hydrocarbons: CH3Cl, CH2Cl2, CHCl3, CCl4, CH3CH2Cl, ClCH2CH2Cl, CH3CHCl2, CH3CCl3, C2H2Cl2-iso, C2H2Cl2-cis, C2H2Cl2-trans, and C6H5Cl. Differences in structural and dynamical properties of the molecules generated by diverse chemical environments are observed in the measured Cl(K(α)) spectral maps as well as in the Cl(K) total fluorescence yield spectra. The energy position, relative intensity, and the width of the Franck-Condon distribution of low-lying σ* and π* resonances are extracted by a fitting procedure taking into account the experimental broadening. The theoretical values obtained with the transition potential and Δ Kohn-Sham methods are in good agreement with the experimental parameters indicating subtle differences due to variations in the molecular structure.

Observations of Ball-Lightning-Like Plasmoids Ejected from Silicon by Localized Microwaves.

PubMed

Meir, Yehuda; Jerby, Eli; Barkay, Zahava; Ashkenazi, Dana; Mitchell, James Brian; Narayanan, Theyencheri; Eliaz, Noam; LeGarrec, Jean-Luc; Sztucki, Michael; Meshcheryakov, Oleg

2013-09-11

This paper presents experimental characterization of plasmoids (fireballs) obtained by directing localized microwave power (<1 kW at 2.45 GHz) onto a silicon-based substrate in a microwave cavity. The plasmoid emerges up from the hotspot created in the solid substrate into the air within the microwave cavity. The experimental diagnostics employed for the fireball characterization in this study include measurements of microwave scattering, optical spectroscopy, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Various characteristics of these plasmoids as dusty plasma are drawn by a theoretical analysis of the experimental observations. Aggregations of dust particles within the plasmoid are detected at nanometer and micrometer scales by both in - situ SAXS and ex-situ SEM measurements. The resemblance of these plasmoids to the natural ball-lightning (BL) phenomenon is discussed with regard to silicon nano-particle clustering and formation of slowly-oxidized silicon micro-spheres within the BL. Potential applications and practical derivatives of this study (e.g., direct conversion of solids to powders, material identification by breakdown spectroscopy (MIBS), thermite ignition, and combustion) are discussed.

BX90: A new diamond anvil cell design for X-ray diffraction and optical measurements

NASA Astrophysics Data System (ADS)

Kantor, I.; Prakapenka, V.; Kantor, A.; Dera, P.; Kurnosov, A.; Sinogeikin, S.; Dubrovinskaia, N.; Dubrovinsky, L.

2012-12-01

We present a new design of a universal diamond anvil cell, suitable for different kinds of experimental studies under high pressures. Main features of the cell are an ultimate 90-degrees symmetrical axial opening and high stability, making the presented cell design suitable for a whole range of techniques from optical absorption to single-crystal X-ray diffraction studies, also in combination with external resistive or double-side laser heating. Three examples of the cell applications are provided: a Brillouin scattering of neon, single-crystal X-ray diffraction of α-Cr2O3, and resistivity measurements on the (Mg0.60Fe0.40)(Si0.63Al0.37)O3 silicate perovskite.

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fournier, K. B., E-mail: fournier2@llnl.gov; Brown, C. G.; Yeoman, M. F.

2016-11-15

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the National Ignition Facility’s diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built-in calorimeters give in situ measurements of the x-ray environment along the sample lines ofmore » sight. The measured accuracy of sample responses as well as planned modifications to the XTRRA cassette is discussed.« less

X-ray transport and radiation response assessment (XTRRA) experiments at the National Ignition Facility

DOE PAGES

Fournier, K. B.; Brown, Jr., C. G.; Yeoman, M. F.; ...

2016-08-10

Our team has developed an experimental platform to evaluate the x-ray-generated stress and impulse in materials. Experimental activities include x-ray source development, design of the sample mounting hardware and sensors interfaced to the NIF’s diagnostics insertion system, and system integration into the facility. This paper focuses on the X-ray Transport and Radiation Response Assessment (XTRRA) test cassettes built for these experiments. The test cassette is designed to position six samples at three predetermined distances from the source, each known to within ±1% accuracy. Built in calorimeters give in situ measurements of the x-ray environment along the sample lines of sight.more » We discuss the measured accuracy of sample responses, as well as planned modifications to the XTRRA cassette.« less

Ameliorative efficacy of bioencapsulated Chironomous larvae with Shilajit on Zebrafish (Danio rerio) exposed to Ionizing radiation.

PubMed

Musthafa, M Saiyad; Athaullah, A; Anbumani, S; Ali, A Jawahar; War, Mehrajuddin; Paray, Bilal Ahmad; Al-Sadoon, Mohammad K; Muthiah, S S; Kembeeram, Palani; Harikrishnan, R

2017-10-01

Using Zebrafish (Danio rerio) as a model organism, we evaluated the radioprotective and antioxidant effects of the Indian traditional medicine Shilajit exposed to X-Ray. The Zebrafish were divided into three experimental groups and control group, each group containing ten fish. The three experimental fish groups, group I, group II and group III were fed with 3, 5 and 7ppm shilajit encapsulated Chironomous larvae and group IV served as a control fed with non- encapsulated larvae. After 60 days of feeding trial, fish were irradiated with X-Ray at a single acute dose of 1Gy. 72h of post-irradiation, each experimental fish were observed for its morphological, behavioral, clinical symptoms, antioxidant levels and DNA damage were evaluated. Among the experimental groups 5ppm shilajit encapsulated Chironomous larvae fed fish group shows the most significant radioprotective effects compared with control and other experimental fish groups. The present study indicates that shilajit have significant radioprotective and antioxidant enhancing capability. The humus substance of shilajit may be the factor responsible to react with radiation-derived or radiation related reactive species on zebrafish. Copyright © 2017 Elsevier Ltd. All rights reserved.

X-ray induced chemical reaction revealed by in-situ X-ray diffraction and scanning X-ray microscopy in 15 nm resolution (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ge, Mingyuan; Liu, Wenjun; Bock, David; De Andrade, Vincent; Yan, Hanfei; Huang, Xiaojing; Marschilok, Amy; Takeuchi, Esther; Xin, Huolin; Chu, Yong S.

2016-09-01

The detection sensitivity of synchrotron-based X-ray techniques has been largely improved due to the ever increasing source brightness, which have significantly advanced ex-situ and in-situ research for energy materials, such as lithium-ion batteries. However, the strong beam-matter interaction arisen from the high beam flux can significantly modify the material structure. The parasitic beam-induced effect inevitably interferes with the intrinsic material property, which brings difficulties in interpreting experimental results, and therefore requires comprehensive evaluation. Here we present a quantitative in-situ study of the beam-effect on one electrode material Ag2VO2PO4 using four different X-ray probes with different radiation dose rate. The material system we reported exhibits interesting and reversible radiation-induced thermal and chemical reactions, which was further evaluated under electron microscopy to illustrate the underlying mechanism. The work we presented here will provide a guideline in using synchrotron X-rays to distinguish the materials' intrinsic behavior from extrinsic structure changed induced by X-rays, especially in the case of in-situ and operando study where the materials are under external field of either temperature or electric field.

Stimulated resonant x-ray Raman scattering with incoherent radiation

NASA Astrophysics Data System (ADS)

Weninger, Clemens; Rohringer, Nina

2013-11-01

We present a theoretical study on stimulated electronic Raman scattering in neon by resonant excitation with an x-ray free electron laser (XFEL). This study is in support of the recent experimental demonstration [C. Weninger , Phys. Rev. Lett. (to be published)] of stimulated x-ray Raman scattering. Focusing the broadband XFEL pulses into a cell of neon gas at atmospheric pressure a strong inelastic x-ray scattering signal in the forward direction was observed, as the x-ray energy was varied across the region of core-excited Rydberg states and the K edge. The broadband and intrinsically incoherent x-ray pulses from the XFEL lead to a rich, structured line shape of the scattered radiation. We present a generalized Maxwell-Liouville-von Neumann approach to self-consistently solve for the amplification of the scattered radiation along with the time evolution of the density matrix of the atomic and residual ionic system. An in-depth analysis of the evolution of the emission spectra as a function of the Raman gain is presented. Furthermore, we propose the use of statistical methods to obtain high-resolution scattering data beyond the lifetime broadening despite pumping with incoherent x-ray pulses.

Photodynamic synchrotron x-ray therapy in Glioma cell using superparamagnetic iron nanoparticle

NASA Astrophysics Data System (ADS)

Kim, Hong-Tae; Kim, Ki-Hong; Choi, Gi-Hwan; Jheon, Sanghoon; Park, Sung-Hwan; Kim, Bong-Il; Hyodo, Kazuyuki; Ando, Masami; Kim, Jong-Ki

2009-06-01

In order to evaluate cytotoxic effects of secondary Auger electron emission(Photon Activation Therapy:PAT) from alginate-coated iron nanoparticles(Alg-SNP), Alg-SNP-uptaken C6 glioma cell lines were irradiated with 6.89/7.2 Kev synchrotron X-ray. 0-125 Gy were irradiated on three experimental groups including No-SNP group incubating without SNP as control group, 6hr-SNP group incubating with SNP for 6hr and ON-SNP group incubating with SNP overnight. Irradiated cells were stained with Acridine Orange(AO) and Edithium Bromide(EB) to count their viability with fluorescent microscopy in comparison with control groups. AO stained in damaged DNA, giving FL color change in X-ray plus SNP group. EB did not or less enter inside the cell nucleus of control group. In contrast, EB entered inside the cell nucleus of Alg-SNP group which means more damage compared with Control groups. The results of MTT assay demonstrated a X-ray dose-dependent reduction generally in cell viability in the experimental groups. 3 or 9 times increase in cell survival loss rate was observed at 6hr-SNP and ON-SNP groups, respectively compared to No-SNP control group in first experiment that was done to test cell survival rate at relatively lower dose, from 0 to 50 Gy. In second experiment X-ray dose was increased to 125 Gy. Survival loss was sharply decreased in a relatively lower dose from 5 to 25 Gy, and then demonstrated an exponentially decreasing behavior with a convergence until 125 Gy for each group. This observation suggests PAT effects on the cell directly by X-ray in the presence of Alg-SNP occurs within lower X-ray dose, and conventional X-ray radiation effect becomes dominant in higher X-ray dose. The cell viability loss of ON-SNP group was three times higher compared with that of 6hr-SNP group. In conclusion, it is possible to design photodynamic X-ray therapy study using a monochromatic x-ray energy and metal nanoparticle as x-ray sensitizer, which may enable new X-ray PDT to disseminated tumors without side effects to normal surrounding tissue.

Observation of divergent-beam X-ray diffraction from a crystal of diamond using synchrotron radiation.

PubMed

Glazer, A M; Collins, S P; Zekria, D; Liu, J; Golshan, M

2004-03-01

In 1947 Kathleen Lonsdale conducted a series of experiments on X-ray diffraction using a divergent beam external to a crystal sample. Unlike the Kossel technique, where divergent X-rays are excited by the presence of fluorescing atoms within the crystal, the use of an external divergent source made it possible to study non-fluorescing crystals. The resulting photographs not only illustrated the complexity of X-ray diffraction from crystals in a truly beautiful way, but also demonstrated unprecedented experimental precision. This long-forgotten work is repeated here using a synchrotron radiation source and, once again, considerable merit is found in Lonsdale's technique. The results of this experiment suggest that, through the use of modern 'third-generation' synchrotron sources, divergent-beam diffraction could soon enjoy a renaissance for high-precision lattice-parameter determination and the study of crystal perfection.

X-ray Imaging and preliminary studies of the X-ray self-emission from an innovative plasma-trap based on the Bernstein waves heating mechanism

NASA Astrophysics Data System (ADS)

Caliri, C.; Romano, F. P.; Mascali, D.; Gammino, S.; Musumarra, A.; Castro, G.; Celona, L.; Neri, L.; Altana, C.

2013-10-01

Electron Cyclotron Resonance Ion Sources (ECRIS) are based on ECR heated plasmas emitting high fluxes of X-rays. Here we illustrate a pilot study of the X-ray emission from a compact plasma-trap in which an off-resonance microwave-plasma interaction has been attempted, highlighting a possible Bernstein-Waves based heating mechanism. EBWs-heating is obtained via the inner plasma EM-to-ES wave conversion and enables to reach densities much larger than the cut-off ones. At LNS-INFN, an innovative diagnostic technique based on the design of a Pinhole Camera (PHC) coupled to a CCD device for X-ray Imaging of the plasma (XRI) has been developed, in order to integrate X-ray traditional diagnostics (XRS). The complementary use of electrostatic probes measurements and X-ray diagnostics enabled us to gain knowledge about the high energy electrons density and temperature and about the spatial structure of the source. The combination of the experimental data with appropriate modeling of the plasma-source allowed to estimate the X-ray emission intensity in different energy domains (ranging from EUV up to Hard X-rays). The use of ECRIS as X-ray source for multidisciplinary applications, is now a concrete perspective due to the intense fluxes produced by the new plasma heating mechanism.

On galactic origin of cosmic rays with energy up to 10(19) eV

NASA Technical Reports Server (NTRS)

Efimov, N. N.; Mikhailov, A. A.

1985-01-01

The experimental data on ultrahigh energy cosmic ray anisotropy are considered. In supposed models of galactic magnetic field the main characteristics of expected anisotropy are estimated and are compared with the experimental data. It is shown that particles with energy up to 10 to the 19th power eV are of galactic origin.

Comprehensive Experimental and Computational Spectroscopic Study of Hexacyanoferrate Complexes in Water: From Infrared to X-ray Wavelengths.

PubMed

Ross, Matthew; Andersen, Amity; Fox, Zachary W; Zhang, Yu; Hong, Kiryong; Lee, Jae-Hyuk; Cordones, Amy; March, Anne Marie; Doumy, Gilles; Southworth, Stephen H; Marcus, Matthew A; Schoenlein, Robert W; Mukamel, Shaul; Govind, Niranjan; Khalil, Munira

2018-05-17

We present a joint experimental and computational study of the hexacyanoferrate aqueous complexes at equilibrium in the 250 meV to 7.15 keV regime. The experiments and the computations include the vibrational spectroscopy of the cyanide ligands, the valence electronic absorption spectra, and Fe 1s core hole spectra using element-specific-resonant X-ray absorption and emission techniques. Density functional theory-based quantum mechanics/molecular mechanics molecular dynamics simulations are performed to generate explicit solute-solvent configurations, which serve as inputs for the spectroscopy calculations of the experiments spanning the IR to X-ray wavelengths. The spectroscopy simulations are performed at the same level of theory across this large energy window, which allows for a systematic comparison of the effects of explicit solute-solvent interactions in the vibrational, valence electronic, and core-level spectra of hexacyanoferrate complexes in water. Although the spectroscopy of hexacyanoferrate complexes in solution has been the subject of several studies, most of the previous works have focused on a narrow energy window and have not accounted for explicit solute-solvent interactions in their spectroscopy simulations. In this work, we focus our analysis on identifying how the local solvation environment around the hexacyanoferrate complexes influences the intensity and line shape of specific spectroscopic features in the UV/vis, X-ray absorption, and valence-to-core X-ray emission spectra. The identification of these features and their relationship to solute-solvent interactions is important because hexacyanoferrate complexes serve as model systems for understanding the photochemistry and photophysics of a large class of Fe(II) and Fe(III) complexes in solution.

Near field interaction of microwave signals with a bounded plasma plume

NASA Technical Reports Server (NTRS)

Ling, Hao; Hallock, Gary A.; Kim, Hyeongdong; Birkner, Bjorn

1991-01-01

The objective was to study the effect of the arcjet thruster plume on the performance of an onboard satellite reflector antenna. A project summary is presented along with sections on plasma and electromagnetic modeling. The plasma modeling section includes the following topics: wave propagation; plasma analysis; plume electron density model; and the proposed experimental program. The section on electromagnetic modeling includes new developments in ray modeling and the validation of three dimensional ray results.

Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

DOE PAGES

Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.; ...

2016-04-01

Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

Microscale electromagnetic heating in heterogeneous energetic materials based on x-ray computed tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kort-Kamp, W. J. M.; Cordes, N. L.; Ionita, A.

Electromagnetic stimulation of energetic materials provides a noninvasive and nondestructive tool for detecting and identifying explosives. We combine structural information based on x-ray computed tomography, experimental dielectric data, and electromagnetic full-wave simulations to study microscale electromagnetic heating of realistic three-dimensional heterogeneous explosives. In conclusion, we analyze the formation of electromagnetic hot spots and thermal gradients in the explosive-binder mesostructures and compare the heating rate for various binder systems.

Detailed transient heme structures of Mb-CO in solution after CO dissociation: an X-ray transient absorption spectroscopic study.

PubMed

Stickrath, Andrew B; Mara, Michael W; Lockard, Jenny V; Harpham, Michael R; Huang, Jier; Zhang, Xiaoyi; Attenkofer, Klaus; Chen, Lin X

2013-04-25

Although understanding the structural dynamics associated with ligand photodissociation is necessary in order to correlate structure and function in biological systems, few techniques are capable of measuring the ultrafast dynamics of these systems in solution-phase at room temperature. We present here a detailed X-ray transient absorption (XTA) study of the photodissociation of CO-bound myoglobin (Fe(II)CO-Mb) in room-temperature aqueous buffer solution with a time resolution of 80 ps, along with a general procedure for handling biological samples under the harsh experimental conditions that transient X-ray experiments entail. The XTA spectra of (Fe(II)CO-Mb) exhibit significant XANES and XAFS alterations following 527 nm excitation, which remain unchanged for >47 μs. These spectral changes indicate loss of the CO ligand, resulting in a five-coordinate, domed heme, and significant energetic reorganization of the 3d orbitals of the Fe center. With the current experimental setup, each X-ray pulse in the pulse train, separated by ~153 ns, can be separately discriminated, yielding snapshots of the myoglobin evolution over time. These methods can be easily applied to other biological systems, allowing for simultaneous structural and electronic measurements of any biological system with both ultrafast and slow time resolutions, effectively mapping out all of the samples' relevant physiological processes.

Investigation of gamma ray shielding, structural and dissolution rate properties of Bi2O3-BaO-B2O3-Na2O glass system

NASA Astrophysics Data System (ADS)

Dogra, Mridula; Singh, K. J.; Kaur, Kulwinder; Anand, Vikas; Kaur, Parminder; Singh, Prabhjot; Bajwa, B. S.

2018-03-01

In the present study, quaternary system of the composition (0.45 + x) Bi2O3-(0.25 - x) BaO-0.15 B2O3-0.15 Na2O (where 0 ≤ x ≤ 0.2 mol fraction) has been prepared by using melt-quenching technique for investigation of gamma ray shielding properties. Mass attenuation coefficients and half value layer parameters have been determined experimentally at 662 keV by using 137Cs source. It has been found that experimental results of these parameters hold good agreement with theoretical values. The density, molar volume, XRD, FTIR, Raman and UV-visible studies have been used to determine structural properties of the prepared glass samples. Dissolution rate of the samples has also been measured to check their utility as long term durable glasses.

X-Ray photoelectron diffraction and photoelectron holography as methods for investigating the local atomic structure of the surface of solids

NASA Astrophysics Data System (ADS)

Kuznetsov, M. V.; Ogorodnikov, I. I.; Vorokh, A. S.

2014-01-01

The state-of-the-art theory and experimental applications of X-ray photoelectron diffraction (XPD) and photoelectron holography (PH) are discussed. These methods are rapidly progressing and serve to examine the surface atomic structure of solids, including nanostructures formed on surfaces during adsorption of gases, epitaxial film growth, etc. The depth of analysis by these methods is several nanometres, which makes it possible to characterize the positions of atoms localized both on and beneath the surface. A remarkable feature of the XPD and PH methods is their sensitivity to the type of examined atoms and, in the case of high energy resolution, to the particular chemical form of the element under study. The data on experimental applications of XPD and PH to studies of various surface structures are analyzed and generalized. The bibliography includes 121 references.

γ-Ray background sources in the VESUVIO spectrometer at ISIS spallation neutron source

NASA Astrophysics Data System (ADS)

Pietropaolo, A.; Perelli Cippo, E.; Gorini, G.; Tardocchi, M.; Schooneveld, E. M.; Andreani, C.; Senesi, R.

2009-09-01

An investigation of the gamma background was carried out in the VESUVIO spectrometer at the ISIS spallation neutron source. This study, performed with a yttrium-aluminum-perovskite (YAP) scintillator, follows high resolution pulse height measurements of the gamma background carried out on the same instrument with the use of a high-purity germanium detector. In this experimental work, a mapping of the gamma background was attempted, trying to find the spatial distribution and degree of directionality of the different contributions identified in the previous study. It is found that the gamma background at low times is highly directional and mostly due to the gamma rays generated in the moderator-decoupler system. The other contributions, consistently to the findings of a previous experiment, are identified as a nearly isotropic one due to neutron absorption in the walls of the experimental hall, and a directional one coming from the beam dump.

Resonant inelastic x-ray scattering on iso-C{sub 2}H{sub 2}Cl{sub 2} around the chlorine K-edge: Structural and dynamical aspects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kawerk, Elie, E-mail: eliekawerk@hotmail.com, E-mail: ekawerk@units.it; Sorbonne Universités, UPMC Université Paris 06, UMR 7614, Laboratoire de Chimie Physique-Matière et Rayonnement, F-75005 Paris; Laboratoire de Physique Appliquée, Faculté des Sciences II, Université Libanaise, 90656 Jdeidet el Metn, Liban

2014-10-14

We report a theoretical and experimental study of the high resolution resonant K{sub α} X-ray emission lines around the chlorine K-edge in gas phase 1,1-dichloroethylene. With the help of ab initio electronic structure calculations and cross section evaluation, we interpret the lowest lying peak in the X-ray absorption and emission spectra. The behavior of the K{sub α} emission lines with respect to frequency detuning highlights the existence of femtosecond nuclear dynamics on the dissociative Potential Energy Surface of the first K-shell core-excited state.

Chloromethyl-oxirane and chloromethyl-thiirane in liquid phase: A joint experimental and quantum chemical study

NASA Astrophysics Data System (ADS)

Campetella, M.; Bencivenni, L.; Caminiti, R.; Zazza, C.; Di Trapani, S.; Martino, A.; Gontrani, L.

2016-07-01

The X-ray diffraction spectra of liquid chloromethyl-oxirane (ClMO) and chloromethyl-thiirane (ClMT) have been recorded for the first time. The interpretation of X-ray measurements was based on ab initio molecular dynamics simulations at finite temperature conditions. Both liquids show conformational equilibrium, which is discussed in terms of Gauche-2, Gauche-1 and Cis structures. The occurrence of the various forms estimated from X-ray and AIMD data has been compared with spectroscopy data from the literature, with the FTIR spectra of the liquids newly recorded in this work, and with theoretical in vacuo calculations.

Simbol-X Mirror Module Thermal Shields: II-Small Angle X-Ray Scattering Measurements

NASA Astrophysics Data System (ADS)

Barbera, M.; Ayers, T.; Collura, A.; Nasillo, G.; Pareschi, G.; Tagliaferri, G.

2009-05-01

The formation flight configuration of the Simbol-X mission implies that the X-ray mirror module will be open to Space on both ends. In order to reduce the power required to maintain the thermal stability and, therefore, the high angular resolution of the shell optics, a thin foil thermal shield will cover the mirror module. Different options are presently being studied for the foil material of these shields. We report results of an experimental investigation conducted to verify that the scattering of X-rays, by interaction with the thin foil material of the thermal shield, will not significantly affect the performances of the telescope.

Spacelab mission 2: Experimental descriptions

NASA Technical Reports Server (NTRS)

Clifton, K. S. (Editor)

1982-01-01

The second Spacelab Mission and the 12 multidisciplinary experiments selected to fly on board are described. These experiments include the following: vitamin D metabolities and bone demineralization; interaction of oxygen and gravity influenced lignification; ejectable plasma diagnostics package; plasma depletion experiments for ionospheric and radio astronomical studies; small helium cooled IR telescope; elemental composition and energy spectra of cosmic ray nuclei; hard X-ray imaging of clusters of galaxies and other extended X-ray sources; solar magnetic and velocity field measurement system; solar coronal helium abundance Spacelab experiment; solar UV high resolution telescope and spectroraph; solar UV spectral irradiance monitor; and properties of superfluid helium in zero-G.

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay.

PubMed

Gong, Zhiliang; Kerr, Daniel; Hwang, Hyeondo Luke; Henderson, J Michael; Suwatthee, Tiffany; Slaw, Benjamin R; Cao, Kathleen D; Lin, Binhua; Bu, Wei; Lee, Ka Yee C

2017-03-01

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca 2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl 2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm 2 of interfacial area contains 2.38 ± 0.06 Ca 2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca 2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr 2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr 2+ at 68 -5 +6 Å 2 per ion, consistent with the result published for the same dataset.

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay

NASA Astrophysics Data System (ADS)

Gong, Zhiliang; Kerr, Daniel; Hwang, Hyeondo Luke; Henderson, J. Michael; Suwatthee, Tiffany; Slaw, Benjamin R.; Cao, Kathleen D.; Lin, Binhua; Bu, Wei; Lee, Ka Yee C.

2017-03-01

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm2 of interfacial area contains 2.38 ± 0.06 Ca2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr2+ at 68-5+6 Å2 per ion, consistent with the result published for the same dataset.

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Zhiliang; Kerr, Daniel; Hwang, Hyeondo Luke

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared tomore » literature results. In an air/liquid interface study, Ca2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm2 of interfacial area contains 2.38 ± 0.06 Ca2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr2+ at 68+6-568-5+6 Å2 per ion, consistent with the result published for the same dataset.« less

Development of low-stress Iridium coatings for astronomical x-ray mirrors

NASA Astrophysics Data System (ADS)

Döhring, Thorsten; Probst, Anne-Catherine; Stollenwerk, Manfred; Wen, Mingwu; Proserpio, Laura

2016-07-01

Previously used mirror technologies are not suitable for the challenging needs of future X-ray telescopes. This is why the required high precision mirror manufacturing triggers new technical developments around the world. Some aspects of X-ray mirrors production are studied within the interdisciplinary project INTRAAST, a German acronym for "industry transfer of astronomical mirror technologies". The project is embedded in a cooperation of Aschaffenburg University of Applied Sciences and the Max-Planck-Institute for extraterrestrial Physics. One important task is the development of low-stress Iridium coatings for X-ray mirrors based on slumped thin glass substrates. The surface figure of the glass substrates is measured before and after the coating process by optical methods. Correlating the surface shape deformation to the parameters of coating deposition, here especially to the Argon sputtering pressure, allows for an optimization of the process. The sputtering parameters also have an influence on the coating layer density and on the micro-roughness of the coatings, influencing their X-ray reflection properties. Unfortunately the optimum coating process parameters seem to be contrarious: low Argon pressure resulted in better micro-roughness and higher density, whereas higher pressure leads to lower coating stress. Therefore additional measures like intermediate coating layers and temperature treatment will be considered for further optimization. The technical approach for the low-stress Iridium coating development, the experimental equipment, and the obtained first experimental results are presented within this paper.

Short-range order of undercooled melts of PdZr2 intermetallic compound studied by X-ray and neutron scattering experiments

NASA Astrophysics Data System (ADS)

Klein, S.; Holland-Moritz, D.; Herlach, D. M.; Mauro, N. A.; Kelton, K. F.

2013-05-01

The short-range order in undercooled melts of the intermetallic Zr2Pd glass-forming alloy is investigated by combining electrostatic levitation (ESL) with high-energy X-ray diffraction and neutron diffraction. Experimentally determined structure factors are measured and analyzed with respect to various structures of short-range order. The comparative X-ray and neutron scattering experiments allow for investigations of topological and chemical short-range order. Based on these studies, no preference of a specific short-range order is found for the liquid Zr2Pd glass-forming alloy, even in the metastable state of the deeply undercooled melt. This is in agreement with an earlier report from X-ray diffraction and molecular-dynamics studies of a Zr75.5Pd24.5 liquid, which showed a broad distribution of cluster types. The results for the Zr2Pd liquid are discussed with respect to the glass-forming ability of this melt.

Preliminary studies of enhanced contrast radiography in anatomy and embryology of insects with Elettra synchrotron light

NASA Astrophysics Data System (ADS)

Hönnicke, M. G.; Foerster, L. A.; Navarro-Silva, M. A.; Menk, R.-H.; Rigon, L.; Cusatis, C.

2005-08-01

Enhanced contrast X-ray imaging is achieved by exploiting the real part of the refraction index, which is responsible for the phase shifts, in addition to the imaginary part, which is responsible for the absorption. Such techniques are called X-ray phase contrast imaging. An analyzer-based X-ray phase contrast imaging set-up with Diffraction Enhanced Imaging processing (DEI) were used for preliminary studies in anatomy and embryology of insects. Parasitized stinkbug and moth eggs used as control agents of pests in vegetables and adult stinkbugs and mosquitoes ( Aedes aegypti) were used as samples. The experimental setup was mounted in the SYRMEP beamline at ELETTRA. Images were obtained using a high spatial resolution CCD detector (pixel size 14×14 μm 2) coupled with magnifying optics. Analyzer-based X-ray phase contrast images (PCI) and edge detection images show contrast and details not observed with conventional synchrotron radiography and open the possibility for future study in the embryonic development of insects.

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

Experimental set-up for time resolved small angle X-ray scattering studies of nanoparticles formation using a free-jet micromixer

NASA Astrophysics Data System (ADS)

Marmiroli, Benedetta; Grenci, Gianluca; Cacho-Nerin, Fernando; Sartori, Barbara; Laggner, Peter; Businaro, Luca; Amenitsch, Heinz

2010-02-01

Recently, we have designed, fabricated and tested a free-jet micromixer for time resolved small angle X-ray scattering (SAXS) studies of nanoparticles formation in the <100 μs time range. The microjet has a diameter of 25 μm and a time of first accessible measurement of 75 μs has been obtained. This result can still be improved. In this communication, we present a method to estimate whether a given chemical or biological reaction can be investigated with the micromixer, and to optimize the beam size for the measurement at the chosen SAXS beamline. Moreover, we describe a system based on stereoscopic imaging which allows the alignment of the jet with the X-ray beam with a precision of 20 μm. The proposed experimental procedures have been successfully employed to observe the formation of calcium carbonate (CaCO 3) nanoparticles from the reaction of sodium carbonate (Na 2CO 3) and calcium chloride (CaCl 2). The induction time has been estimated in the order of 200 μs and the determined radius of the particles is about 14 nm.

Understanding the effects of Cr doping in rutile TiO2 by DFT calculations and X-ray spectroscopy.

PubMed

Vásquez, G Cristian; Maestre, David; Cremades, Ana; Ramírez-Castellanos, Julio; Magnano, Elena; Nappini, Silvia; Karazhanov, Smagul Zh

2018-06-07

The effects of Cr on local environment and electronic structure of rutile TiO 2 are studied combining theoretical and experimental approaches. Neutral and negatively charged substitutional Cr impurities Cr Ti 0 and Cr Ti 1- as well as Cr-oxygen vacancy complex 2Cr Ti  + V O are studied by the density functional theory (DFT) within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) functional. Experimental results based on X-Ray absorption spectroscopy (XAS) and X-Ray photoelectron spectroscopy (XPS) performed on Cr doped TiO 2 at the Synchrotron facility were compared to the theoretical results. It is shown that the electrons of the oxygen vacancy tend to be localized at the t 2g states of the Cr ions in order to reach the stable oxidation state of Cr 3+ . Effects of Cr on crystal field (CF) and structural distortions in the rutile TiO 2 cell were analyzed by the DFT calculations and XAS spectra revealing that the CF and tetragonal distortions in TiO 2 are very sensitive to the concentration of Cr.

Reduction of variable-truncation artifacts from beam occlusion during in situ x-ray tomography

NASA Astrophysics Data System (ADS)

Borg, Leise; Jørgensen, Jakob S.; Frikel, Jürgen; Sporring, Jon

2017-12-01

Many in situ x-ray tomography studies require experimental rigs which may partially occlude the beam and cause parts of the projection data to be missing. In a study of fluid flow in porous chalk using a percolation cell with four metal bars drastic streak artifacts arise in the filtered backprojection (FBP) reconstruction at certain orientations. Projections with non-trivial variable truncation caused by the metal bars are the source of these variable-truncation artifacts. To understand the artifacts a mathematical model of variable-truncation data as a function of metal bar radius and distance to sample is derived and verified numerically and with experimental data. The model accurately describes the arising variable-truncation artifacts across simulated variations of the experimental setup. Three variable-truncation artifact-reduction methods are proposed, all aimed at addressing sinogram discontinuities that are shown to be the source of the streaks. The ‘reduction to limited angle’ (RLA) method simply keeps only non-truncated projections; the ‘detector-directed smoothing’ (DDS) method smooths the discontinuities; while the ‘reflexive boundary condition’ (RBC) method enforces a zero derivative at the discontinuities. Experimental results using both simulated and real data show that the proposed methods effectively reduce variable-truncation artifacts. The RBC method is found to provide the best artifact reduction and preservation of image features using both visual and quantitative assessment. The analysis and artifact-reduction methods are designed in context of FBP reconstruction motivated by computational efficiency practical for large, real synchrotron data. While a specific variable-truncation case is considered, the proposed methods can be applied to general data cut-offs arising in different in situ x-ray tomography experiments.

An experimental investigation of gas fuel injection with X-ray radiography

DOE PAGES

Swantek, Andrew B.; Duke, D. J.; Kastengren, A. L.; ...

2017-04-21

In this paper, an outward-opening compressed natural gas, direct injection fuel injector has been studied with single-shot x-ray radiography. Three dimensional simulations have also been performed to compliment the x-ray data. Argon was used as a surrogate gas for experimental and safety reasons. This technique allows the acquisition of a quantitative mapping of the ensemble-average and standard deviation of the projected density throughout the injection event. Two dimensional, ensemble average and standard deviation data are presented to investigate the quasi-steady-state behavior of the jet. Upstream of the stagnation zone, minimal shot-to-shot variation is observed. Downstream of the stagnation zone, bulkmore » mixing is observed as the jet transitions to a subsonic turbulent jet. From the time averaged data, individual slices at all downstream locations are extracted and an Abel inversion was performed to compute the radial density distribution, which was interpolated to create three dimensional visualizations. The Abel reconstructions reveal that upstream of the stagnation zone, the gas forms an annulus with high argon density and large density gradients. Inside this annulus, a recirculation region with low argon density exists. Downstream, the jet transitions to a fully turbulent jet with Gaussian argon density distributions. This experimental data is intended to serve as a quantitative benchmark for simulations.« less

An experimental investigation of gas fuel injection with X-ray radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swantek, Andrew B.; Duke, D. J.; Kastengren, A. L.

In this paper, an outward-opening compressed natural gas, direct injection fuel injector has been studied with single-shot x-ray radiography. Three dimensional simulations have also been performed to compliment the x-ray data. Argon was used as a surrogate gas for experimental and safety reasons. This technique allows the acquisition of a quantitative mapping of the ensemble-average and standard deviation of the projected density throughout the injection event. Two dimensional, ensemble average and standard deviation data are presented to investigate the quasi-steady-state behavior of the jet. Upstream of the stagnation zone, minimal shot-to-shot variation is observed. Downstream of the stagnation zone, bulkmore » mixing is observed as the jet transitions to a subsonic turbulent jet. From the time averaged data, individual slices at all downstream locations are extracted and an Abel inversion was performed to compute the radial density distribution, which was interpolated to create three dimensional visualizations. The Abel reconstructions reveal that upstream of the stagnation zone, the gas forms an annulus with high argon density and large density gradients. Inside this annulus, a recirculation region with low argon density exists. Downstream, the jet transitions to a fully turbulent jet with Gaussian argon density distributions. This experimental data is intended to serve as a quantitative benchmark for simulations.« less

Experimental demonstration of a soft x-ray self-seeded free-electron laser.

PubMed

Ratner, D; Abela, R; Amann, J; Behrens, C; Bohler, D; Bouchard, G; Bostedt, C; Boyes, M; Chow, K; Cocco, D; Decker, F J; Ding, Y; Eckman, C; Emma, P; Fairley, D; Feng, Y; Field, C; Flechsig, U; Gassner, G; Hastings, J; Heimann, P; Huang, Z; Kelez, N; Krzywinski, J; Loos, H; Lutman, A; Marinelli, A; Marcus, G; Maxwell, T; Montanez, P; Moeller, S; Morton, D; Nuhn, H D; Rodes, N; Schlotter, W; Serkez, S; Stevens, T; Turner, J; Walz, D; Welch, J; Wu, J

2015-02-06

The Linac Coherent Light Source has added a self-seeding capability to the soft x-ray range using a grating monochromator system. We report the demonstration of soft x-ray self-seeding with a measured resolving power of 2000-5000, wavelength stability of 10(-4), and an increase in peak brightness by a factor of 2-5 across the photon energy range of 500-1000 eV. By avoiding the need for a monochromator at the experimental station, the self-seeded beam can deliver as much as 50-fold higher brightness to users.

Resolving hot spot microstructure using x-ray penumbral imaging (invited)

NASA Astrophysics Data System (ADS)

Bachmann, B.; Hilsabeck, T.; Field, J.; Masters, N.; Reed, C.; Pardini, T.; Rygg, J. R.; Alexander, N.; Benedetti, L. R.; Döppner, T.; Forsman, A.; Izumi, N.; LePape, S.; Ma, T.; MacPhee, A. G.; Nagel, S.; Patel, P.; Spears, B.; Landen, O. L.

2016-11-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Experimental Summary: Very High Energy Cosmic Rays and their Interactions

NASA Astrophysics Data System (ADS)

Kampert, Karl-Heinz

2013-06-01

The XVII International Symposium on Very High Energy Cosmic Ray Interactions, held in August of 2012 in Berlin, was the first one in the history of the Symposium,where a plethora of high precision LHC data with relevance for cosmic ray physics was presented. This report aims at giving a brief summary of those measurements andit discusses their relevance for observations of high energy cosmic rays. Enormous progress has been made also in air shower observations and in direct measurements of cosmic rays, exhibiting many more structure in the cosmic ray energy spectrum than just a simple power law with a knee and an ankle. At the highest energy, the flux suppression may not be dominated by the GZK-effect but by the limiting energy of a nearby source or source population. New projects and application of new technologies promise further advances also in the near future. We shall discuss the experimental and theoretical progress in the field and its prospects for coming years.

Resolving hot spot microstructure using x-ray penumbral imaging (invited).

PubMed

Bachmann, B; Hilsabeck, T; Field, J; Masters, N; Reed, C; Pardini, T; Rygg, J R; Alexander, N; Benedetti, L R; Döppner, T; Forsman, A; Izumi, N; LePape, S; Ma, T; MacPhee, A G; Nagel, S; Patel, P; Spears, B; Landen, O L

2016-11-01

We have developed and fielded x-ray penumbral imaging on the National Ignition Facility in order to enable sub-10 μm resolution imaging of stagnated plasma cores (hot spots) of spherically shock compressed spheres and shell implosion targets. By utilizing circular tungsten and tantalum apertures with diameters ranging from 20 μm to 2 mm, in combination with image plate and gated x-ray detectors as well as imaging magnifications ranging from 4 to 64, we have demonstrated high-resolution imaging of hot spot plasmas at x-ray energies above 5 keV. Here we give an overview of the experimental design criteria involved and demonstrate the most relevant influences on the reconstruction of x-ray penumbral images, as well as mitigation strategies of image degrading effects like over-exposed pixels, artifacts, and photon limited source emission. We describe experimental results showing the advantages of x-ray penumbral imaging over conventional Fraunhofer and photon limited pinhole imaging and showcase how internal hot spot microstructures can be resolved.

Experimental investigation of dynamic fragmentation of laser shock-loaded by soft recovery and X-ray radiography

NASA Astrophysics Data System (ADS)

Xin, Jianting; He, Weihua; Chu, Genbai; Gu, Yuqiu

2017-06-01

Dynamic fragmentation of metal under shock pressure is an important issue for both fundamental science and practical applications. And in recent decades, laser provides a promising shock loading technique for investigating the process of dynamic fragmentation under extreme condition application of high strain rate. Our group has performed experimental investigation of dynamic fragmentation under laser shock loading by soft recovery and X-ray radiography at SGC / ó prototype laser facility. The fragments under different loading pressures were recovered by PMP foam and analyzed by X-ray micro-tomography and the improved watershed method. The experiment result showed that the bilinear exponential distribution is more appropriate for representing the fragment size distribution. We also developed X-ray radiography technique. Owing to its inherent advantage over shadowgraph technique, X-ray radiography can potentially determine quantitatively material densities by measuring the X-ray transmission. Our group investigated dynamic process of microjetting by X-ray radiography technique, the recorded radiographic images show clear microjetting from the triangular grooves in the free surface of tin sample.

Experimental (13C NMR, 1H NMR, FT-IR, single-crystal X-ray diffraction) and DFT studies on 3,4-bis(isoproylamino)cyclobut-3-ene-1,2-dione.

PubMed

Süleymanoğlu, Nevin; Ustabaş, Reşat; Alpaslan, Yelda Bingöl; Eyduran, Fatih; Ozyürek, Cengiz; Iskeleli, Nazan Ocak

2011-12-01

In this work, 3,4-bis(isoproylamino)cyclobut-3-ene-1,2-dione C(10)H(16)N(2)O(2) (I), was synthesized and characterized by (13)C NMR, (1)H NMR, FT-IR, UV-vis spectroscopy and single-crystal X-ray diffraction. DFT method with 6-31G(d,p) basis set has been used to calculate the optimized geometrical parameters, atomic charges, vibrational frequencies and chemical shift values. The calculated vibrational frequencies and chemical shift values are compared with experimental FT-IR and NMR spectra. The results of the calculation shows good agreement between experimental and calculated values of the compound I. The existence of N-H⋯O type intermolecular ve C-H⋯O type intramolecular hydrogen bonds can be deduced from differences between experimental and calculated results of FT-IR and NMR. In addition, the molecular electrostatic potential map and frontier molecular orbitals and electronic absorption spectra were performed at B3LYP/6-31G(d,p) level of theory. HOMO-LUMO electronic transition of 4.90 eV are derived from the contribution of the bands π→π* and n→π* The spectral results obtained from FT-IR, NMR and X-ray of I revealed that the compound I is in predominantly enamine tautomeric form, which was supported by DFT calculations. Copyright © 2011 Elsevier B.V. All rights reserved.

Contribution from individual nearby sources to the spectrum of high-energy cosmic-ray electrons

NASA Astrophysics Data System (ADS)

Sedrati, R.; Attallah, R.

2014-04-01

In the last few years, very important data on high-energy cosmic-ray electrons and positrons from high-precision space-born and ground-based experiments have attracted a great deal of interest. These particles represent a unique probe for studying local comic-ray accelerators because they lose energy very rapidly. These energy losses reduce the lifetime so drastically that high-energy cosmic-ray electrons can attain the Earth only from rather local astrophysical sources. This work aims at calculating, by means of Monte Carlo simulation, the contribution from some known nearby astrophysical sources to the cosmic-ray electron/positron spectra at high energy (≥ 10 GeV). The background to the electron energy spectrum from distant sources is determined with the help of the GALPROP code. The obtained numerical results are compared with a set of experimental data.

The sensitivity of EGRET to gamma ray polarization

NASA Astrophysics Data System (ADS)

Mattox, John R.

1990-05-01

A Monte Carlo simulation shows that EGRET (Energetic Gamma-Ray Experimental Telescope) does not even have sufficient sensitivity to detect 100 percent polarized gamma-rays. This is confirmed by analysis of calibration data. A Monte Carlo study shows that the sensitivity of EGRET to polarization peaks around 100 MeV. However, more than 10 5 gamma-ray events with 100 percent polarization would be required for a 3 sigma significance detection - more than available from calibration, and probably more than will result from a single score source during flight. A drift chamber gamma ray telescope under development (Hunter and Cuddapah 1989) will offer better sensitivity to polarization. The lateral position uncertainty will be improved by an order of magnitude. Also, if pair production occurs in the drift chamber gas (xenon at 2 bar) instead of tantalum foils, the effects of multiple Coulomb scattering will be reduced.

The study of chemical composition and elemental mappings of colored over-glaze porcelain fired in Qing Dynasty by micro-X-ray fluorescence

NASA Astrophysics Data System (ADS)

Lin, Cheng; Meitian, Li; Youshi, Kim; Changsheng, Fan; Shanghai, Wang; Qiuli, Pan; Zhiguo, Liu; Rongwu, Li

2011-02-01

It is very difficult to measure the chemical composition of colored pigments of over-glaze porcelain by X-ray fluorescence because it contains high concentration of Pb. One of the disadvantages of our polycapillary optics is that it has low transmission efficiency to the high energy X-ray. However, it is beneficial to measure the chemical compositions of rich Pb sample. In this paper, we reported the performances of a tabletop setup of micro-X-ray fluorescence system base on slightly focusing polycapillary and its applications for analysis of rich Pb sample. A piece of Chinese ancient over-glaze porcelain was analyzed by micro-X-ray fluorescence. The experimental results showed that the Cu, Fe and Mn are the major color elements. The possibilities of the process of decorative technology were discussed in this paper, also.

Study of fission fragment de-excitation by gamma-ray spectrometry with the EXILL experiment

NASA Astrophysics Data System (ADS)

Materna, Thomas; a, Michal Rapał; Letourneau, Alain; Marchix, Anthony; Litaize, Olivier; Sérot, Olivier; Urban, Waldemar; Blanc, Aurélien; Jentschel, Michael; Köster, Ulli; Mutti, Paolo; Soldner, Torsten; Simpson, Gary; Ur, Călin A.; France, Gilles de

2017-09-01

A large array of Ge detectors installed at ILL, around a 235U target irradiated with cold neutrons, (EXILL) allowed measurement of prompt gamma-ray cascades occurring in fission fragments with an unambiguous determination of fragments. Here we present preliminary results of a systematic comparison between experimental γ-ray intensities and those obtained from the Monte-Carlo simulation code FIFRELIN, which is dedicated to the de-excitation of fission fragments. Major γ-ray intensities in the 142Ba and 92Kr fission products, extracted from EXILL data, were compared to FIFRELIN, as well as to reported values (when available) obtained with EUROGAM2 in the spontaneous fission of 248Cm. The evolution of γ-ray intensities in 92Kr versus the complementary partner in fission (i.e. versus the total number of evaporated neutrons by the fission pair) was then extracted and compared to FIFRELIN.

Ultrafast secondary emission X-ray imaging detectors: A possible application to TRD

NASA Astrophysics Data System (ADS)

Akkerman, A.; Breskin, A.; Chechik, R.; Elkind, V.; Gibrekhterman, A.; Majewski, S.

1992-05-01

Fist high accuracy, X-ray imaging at high photon flux can be achieved when coupling thin solid convertors to gaseous electron multipliers, operating at low gas pressures. Secondary electrons emitted from the convertor foil are multiplied in several successive amplification elements. The obvious advantages of solid X-ray convertors, as compared to gaseous conversion, are the production of parallax-free images and the fast (subnanosecond) response. These X-ray detectors have many potential applications in basic and applied research. Of particular interest is the possibility of an efficient and ultrafast high resolution imaging of transition radiation (TR), with a reduced d E/d x background. We present experimental results on the operation of secondary emission X-ray (SEX) detectors, their detection efficiency, localization and time resolution. The experimental work is accompanied by mathematical modelling and computer simulation of transition radiation detectors (TRDs) based on CsI TR convertors.

FIER: Software for analytical modeling of delayed gamma-ray spectra

NASA Astrophysics Data System (ADS)

Matthews, E. F.; Goldblum, B. L.; Bernstein, L. A.; Quiter, B. J.; Brown, J. A.; Younes, W.; Burke, J. T.; Padgett, S. W.; Ressler, J. J.; Tonchev, A. P.

2018-05-01

A new software package, the Fission Induced Electromagnetic Response (FIER) code, has been developed to analytically predict delayed γ-ray spectra following fission. FIER uses evaluated nuclear data and solutions to the Bateman equations to calculate the time-dependent populations of fission products and their decay daughters resulting from irradiation of a fissionable isotope. These populations are then used in the calculation of γ-ray emission rates to obtain the corresponding delayed γ-ray spectra. FIER output was compared to experimental data obtained by irradiation of a 235U sample in the Godiva critical assembly. This investigation illuminated discrepancies in the input nuclear data libraries, showcasing the usefulness of FIER as a tool to address nuclear data deficiencies through comparison with experimental data. FIER provides traceability between γ-ray emissions and their contributing nuclear species, decay chains, and parent fission fragments, yielding a new capability for the nuclear science community.

X-ray and neutron diffraction studies of crystallinity in hydroxyapatite coatings.

PubMed

Girardin, E; Millet, P; Lodini, A

2000-02-01

To standardize industrial implant production and make comparisons between different experimental results, we have to be able to quantify the crystallinity of hydroxyapatite. Methods of measuring crystallinity ratio were developed for various HA samples before and after plasma spraying. The first series of methods uses X-ray diffraction. The advantage of these methods is that X-ray diffraction equipment is used widely in science and industry. In the second series, a neutron diffraction method is developed and the results recorded are similar to those obtained by the modified X-ray diffraction methods. The advantage of neutron diffraction is the ability to obtain measurements deep inside a component. It is a nondestructive method, owing to the very low absorption of neutrons in most materials. Copyright 2000 John Wiley & Sons, Inc.

New experimental platform to study high density laser-compressed matter

DOE PAGES

Doppner, T.; LePape, S.; Ma, T.; ...

2014-09-26

We have developed a new experimental platform at the Linac Coherent Light Source (LCLS) which combines simultaneous angularly and spectrally resolved x-ray scatteringmeasurements. This technique offers a new insights on the structural and thermodynamic properties of warm dense matter. The < 50 fs temporal duration of the x-ray pulse provides near instantaneous snapshots of the dynamics of the compression. We present a proof of principle experiment for this platform to characterize a shock-compressed plastic foil. We observe the disappearance of the plastic semi-crystal structure and the formation of a compressed liquid ion-ion correlation peak. As a result, the plasma parametersmore » of shock-compressed plastic can be measured as well, but requires an averaging over a few tens of shots.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Richard, A. L.; Crawford, H. L.; Fallon, P.

The “island of inversion” at N≈20 for the neon, sodium, and magnesium isotopes has long been an area of interest both experimentally and theoretically due to the subtle competition between 0p-0h and np-nh configurations leading to deformed shapes. However, the presence of rotational band structures, which are fingerprints of deformed shapes, have only recently been observed in this region. In this work, we report on a measurement of the low-lying level structure of Mg33 populated by a two-stage projectile fragmentation reaction and studied with the Gamma Ray Energy Tracking In-Beam Nuclear Array (GRETINA). The experimental level energies, ground-state magnetic moment,more » intrinsic quadrupole moment, and γ-ray intensities show good agreement with the strong-coupling limit of a rotational model.« less

The effect of porosity on the mechanical properties of porous titanium scaffolds: comparative study on experimental and analytical values

NASA Astrophysics Data System (ADS)

Khodaei, Mohammad; Fathi, Mohammadhossein; Meratian, Mahmood; Savabi, Omid

2018-05-01

Reducing the elastic modulus and also improving biological fixation to the bone is possible by using porous scaffolds. In the present study, porous titanium scaffolds containing different porosities were fabricated using the space holder method. Pore distribution, formed phases and mechanical properties of titanium scaffolds were studied by Scanning Electron Microscope (SEM), x-ray diffraction (XRD) and cold compression test. Then the results of compression test were compared to the Gibson-Ashby model. Both experimentally measured and analytically calculated elastic modulus of porous titanium scaffolds decreased by porosity increment. The compliance between experimentally measured and analytically calculated elastic modulus of titanium scaffolds are also increased by porosity increment.

Gamma-Ray background spectrum and annihilation rate in the baryon-symmetric big-bang cosmology

NASA Technical Reports Server (NTRS)

Puget, J. L.

1973-01-01

An attempt was made to extract experimental data on baryon symmetry by observing annihilation products. Specifically, gamma rays and neutrons with long mean free paths were analyzed. Data cover absorption cross sections and radiation background of the 0.511 MeV gamma rays from positron annihilations and the 70 MeV gamma rays from neutral pion decay.

Cosmic-ray effects on diffuse gamma-ray measurements.

NASA Technical Reports Server (NTRS)

Fishman, G. J.

1972-01-01

Evaluation of calculations and experimental evidence from 600-MeV proton irradiation indicating that cosmic-ray-induced radioactivity in detectors used to measure the diffuse gamma-ray background produces a significant counting rate in the energy region around 1 MeV. It is concluded that these counts may be responsible for the observed flattening of the diffuse photon spectrum at this energy.

A Brief Change in Housing Conditions Alters the Survivability of Irradiated C3H/HeN Mice

DTIC Science & Technology

1992-03-04

Sacher, G.A., Gratin, D., Hamilton, K ., and Sallese, A. (1965). Survival of mice under duration-of-life exposure to gamma rays, Radiation Research, 24, 239...exposures of mice to fission neutrons and Co 60 gamma rays, Radiation Research, 68, 386-397. 16. Ainsworth, E.J., Leong, G.F., Kendall, K ., and Alpen...R.P., and Yagi, K . (1962). Experimental studies of psychological stress in man, Psychological Monolrauhs, 76,(15), Whole No. 534. 36. Brady, J.V. (1984

Functional materials analysis using in situ and in operando X-ray and neutron scattering

PubMed Central

Peterson, Vanessa K.; Papadakis, Christine M.

2015-01-01

In situ and in operando studies are commonplace and necessary in functional materials research. This review highlights recent developments in the analysis of functional materials using state-of-the-art in situ and in operando X-ray and neutron scattering and analysis. Examples are given covering a number of important materials areas, alongside a description of the types of information that can be obtained and the experimental setups used to acquire them. PMID:25866665

Stacked Fresnel Zone Plates for High Energy X-rays

NASA Astrophysics Data System (ADS)

Snigireva, Irina; Snigirev, Anatoly; Vaughan, Gavin; Di Michiel, Marco; Kohn, Viktor; Yunkin, Vyacheslav; Grigoriev, Maxim

2007-01-01

A stacking technique was developed in order to increase focusing efficiency of Fresnel zone plates (FZP) at high energies. Two identical Si chips each of which containing 9 FZPs were used for stacking. Alignment of the chips was achieved by on-line observation of the moiré pattern. The formation of moiré patterns was studied theoretically and experimentally at different experimental conditions. To provide the desired stability Si-chips were bonded together with slow solidification speed epoxy glue. A technique of angular alignment in order to compensate a linear displacement in the process of gluing was proposed. Two sets of stacked FZPs were experimentally tested to focus 15 and 50 keV x rays. The gain in the efficiency by factor 2.5 was demonstrated at 15 keV. The focal spot of 1.8 μm vertically and 14 μm horizontally with 35% efficiency was measured at 50 keV. Forecast for the stacking of nanofocusing FZPs was discussed.

Hard X-ray focusing by stacked Fresnel zone plates

NASA Astrophysics Data System (ADS)

Snigireva, Irina; Snigirev, Anatoly; Kohn, Viktor; Yunkin, Vyacheslav; Grigoriev, Maxim; Kuznetsov, Serguei; Vaughan, Gavin; Di Michiel, Marco

2007-09-01

Stacking technique was developed in order to increase focusing efficiency of Fresnel zone plates at high energies. Two identical Si chips each of which containing Fresnel zone plates were used for stacking. Alignment of the chips was achieved by on-line observation of the moiré pattern from the two zone plates. The formation of moiré patterns was studied theoretically and experimentally at different experimental conditions. To provide the desired stability Si-chips with zone plates were bonded together with slow solidification speed epoxy glue. Technique of angular alignment in order to compensate a linear displacement in the process of gluing was proposed. Two sets of stacked FZPs were produced and experimentally tested to focus 15 and 50 keV X-rays. Gain in the efficiency by factor 2.5 was demonstrated at 15 keV. Focal spot of 1.8 μm vertically and 14 μm horizontally with 35% efficiency was measured at 50 keV. Forecast for the stacking of nanofocusing Fresnel zone plates was discussed.

Experimental evidence of low-density liquid water upon rapid decompression

PubMed Central

Lin, Chuanlong; Smith, Jesse S.; Sinogeikin, Stanislav V.; Shen, Guoyin

2018-01-01

Water is an extraordinary liquid, having a number of anomalous properties which become strongly enhanced in the supercooled region. Due to rapid crystallization of supercooled water, there exists a region that has been experimentally inaccessible for studying deeply supercooled bulk water. Using a rapid decompression technique integrated with in situ X-ray diffraction, we show that a high-pressure ice phase transforms to a low-density noncrystalline (LDN) form upon rapid release of pressure at temperatures of 140–165 K. The LDN subsequently crystallizes into ice-Ic through a diffusion-controlled process. Together with the change in crystallization rate with temperature, the experimental evidence indicates that the LDN is a low-density liquid (LDL). The measured X-ray diffraction data show that the LDL is tetrahedrally coordinated with the tetrahedral network fully developed and clearly linked to low-density amorphous ices. On the other hand, there is a distinct difference in structure between the LDL and supercooled water or liquid water in terms of the tetrahedral order parameter. PMID:29440411

Effect of aluminum on the local structure of silicon in zeolites as studied by Si K edge X-ray absorption near-edge fine structure: spectra simulation with a non-muffin tin atomic background.

PubMed

Bugaev, Lusegen A; Bokhoven, Jeroen A van; Khrapko, Valerii V

2009-04-09

Experimental Si K edge X-ray absorption near-edge fine structure (XANES) of zeolite faujasite, mordenite, and beta are interpreted by means of the FEFF8 code, replacing the theoretical atomic background mu(0) by a background that was extracted from an experimental spectrum. To some extent, this diminished the effect of the inaccuracy introduced by the MT potential and accounted for the intrinsic loss of photoelectrons. The agreement of the theoretical and experimental spectra at energies above the white lines enabled us to identify structural distortion around silicon, which occurs with increasing aluminum content. The Si K edge XANES spectra are very sensitive to slight distortions in the silicon coordination. Placing an aluminum atom on a nearest neighboring T site causes a distortion in the silicon tetrahedron, shortening one of the silicon-oxygen bonds relative to the other three.

Optical, Fluorescence with quantum analysis of hydrazine (1, 3- Dinitro Phenyl) by DFT and Ab initio approach

NASA Astrophysics Data System (ADS)

Cecily Mary Glory, D.; Sambathkumar, K.; Madivanane, R.; Velmurugan, G.; Gayathri, R.; Nithiyanantham, S.; Venkatachalapathy, M.; Rajkamal, N.

2018-07-01

Experimental and computational study of molecular structure, vibrational and UV-spectral analysis of Hydrazine (1, 3- Dinitrophenyl) (HDP) derivatives. The crystal was grown by slow cooling method and the crystalline perfection of single crystals was evaluated by high resolution X-ray diffractometry (HRXRD) using a multicrystal X-ray diffractometer. Fluorescence, FT-IR and FT-Raman spectra of HDP crystal were recorded. The assignments of the vibrational spectra have been carried out with the help of normal co-ordinate analysis (NCA) followed by scaled quantum force field methodology (SQMFF). NMR studies have confirmed respectively the crystal structure and functional groups of the grown crystal. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) result complements the experimental findings. The calculated MESP, UV, HOMO-LUMO energies show that charge transfer done within the molecule. And various thermodynamic parameters are studied. Fukui determines the local reactive site of electrophilic, nucleophilic, descriptor.

Interarticulator Coordination in Dysarthria: An X-Ray Microbeam Study

ERIC Educational Resources Information Center

Weismer, Gary; Yunusova, Yana; Westbury, John R.

2003-01-01

Articulatory discoordination is often said to be an important feature of the speech production disorder in dysarthria, but little experimental work has been done to identify and specify the coordination difficulties. The present study evaluated the coordination of labial and lingual gestures for /u/ production in persons with Parkinson's disease…

Comparison of adverse effects of proton and X-ray chemoradiotherapy for esophageal cancer using an adaptive dose–volume histogram analysis

PubMed Central

Makishima, Hirokazu; Ishikawa, Hitoshi; Terunuma, Toshiyuki; Hashimoto, Takayuki; Yamanashi, Koichi; Sekiguchi, Takao; Mizumoto, Masashi; Okumura, Toshiyuki; Sakae, Takeji; Sakurai, Hideyuki

2015-01-01

Cardiopulmonary late toxicity is of concern in concurrent chemoradiotherapy (CCRT) for esophageal cancer. The aim of this study was to examine the benefit of proton beam therapy (PBT) using clinical data and adaptive dose–volume histogram (DVH) analysis. The subjects were 44 patients with esophageal cancer who underwent definitive CCRT using X-rays (n = 19) or protons (n = 25). Experimental recalculation using protons was performed for the patient actually treated with X-rays, and vice versa. Target coverage and dose constraints of normal tissues were conserved. Lung V5–V20, mean lung dose (MLD), and heart V30–V50 were compared for risk organ doses between experimental plans and actual treatment plans. Potential toxicity was estimated using protons in patients actually treated with X-rays, and vice versa. Pulmonary events of Grade ≥2 occurred in 8/44 cases (18%), and cardiac events were seen in 11 cases (25%). Risk organ doses in patients with events of Grade ≥2 were significantly higher than for those with events of Grade ≤1. Risk organ doses were lower in proton plans compared with X-ray plans. All patients suffering toxicity who were treated with X-rays (n = 13) had reduced predicted doses in lung and heart using protons, while doses in all patients treated with protons (n = 24) with toxicity of Grade ≤1 had worsened predicted toxicity with X-rays. Analysis of normal tissue complication probability showed a potential reduction in toxicity by using proton beams. Irradiation dose, volume and adverse effects on the heart and lung can be reduced using protons. Thus, PBT is a promising treatment modality for the management of esophageal cancer. PMID:25755255

Simulation and experimental verification of prompt gamma-ray emissions during proton irradiation.

PubMed

Schumann, A; Petzoldt, J; Dendooven, P; Enghardt, W; Golnik, C; Hueso-González, F; Kormoll, T; Pausch, G; Roemer, K; Fiedler, F

2015-05-21

Irradiation with protons and light ions offers new possibilities for tumor therapy but has a strong need for novel imaging modalities for treatment verification. The development of new detector systems, which can provide an in vivo range assessment or dosimetry, requires an accurate knowledge of the secondary radiation field and reliable Monte Carlo simulations. This paper presents multiple measurements to characterize the prompt γ-ray emissions during proton irradiation and benchmarks the latest Geant4 code against the experimental findings. Within the scope of this work, the total photon yield for different target materials, the energy spectra as well as the γ-ray depth profile were assessed. Experiments were performed at the superconducting AGOR cyclotron at KVI-CART, University of Groningen. Properties of the γ-ray emissions were experimentally determined. The prompt γ-ray emissions were measured utilizing a conventional HPGe detector system (Clover) and quantitatively compared to simulations. With the selected physics list QGSP_BIC_HP, Geant4 strongly overestimates the photon yield in most cases, sometimes up to 50%. The shape of the spectrum and qualitative occurrence of discrete γ lines is reproduced accurately. A sliced phantom was designed to determine the depth profile of the photons. The position of the distal fall-off in the simulations agrees with the measurements, albeit the peak height is also overestimated. Hence, Geant4 simulations of prompt γ-ray emissions from irradiation with protons are currently far less reliable as compared to simulations of the electromagnetic processes. Deviations from experimental findings were observed and quantified. Although there has been a constant improvement of Geant4 in the hadronic sector, there is still a gap to close.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sisniega, A.; Vaquero, J. J., E-mail: juanjose.vaquero@uc3m.es; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007

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, modifiedmore » 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.« less

Gamma-Ray Spectroscopy at TRIUMF-ISAC: the New Frontier of Radioactive Ion Beam Research

NASA Astrophysics Data System (ADS)

Ball, G. C.; Andreoiu, C.; Austin, R. A. E.; Bandyopadhyay, D.; Becker, J. A.; Bricault, P.; Brown, N.; Chan, S.; Churchman, R.; Colosimo, S.; Coombes, H.; Cross, D.; Demand, G.; Drake, T. E.; Dombsky, M.; Ettenauer, S.; Finlay, P.; Furse, D.; Garnsworthy, A.; Garrett, P. E.; Green, K. L.; Grinyer, G. F.; Hyland, B.; Hackman, G.; Kanungo, R.; Kulp, W. D.; Lassen, J.; Leach, K. G.; Leslie, J. R.; Mattoon, C.; Melconian, D.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Rand, E.; Sarazin, F.; Svensson, C. E.; Sumithrarachchi, S.; Schumaker, M. A.; Triambak, S.; Waddington, J. C.; Walker, P. M.; Williams, S. J.; Wood, J. L.; Wong, J.; Zganjar, E. F.

2009-03-01

High-resolution gamma-ray spectroscopy is essential to fully exploit the unique scientific opportunities at the next generation radioactive ion beam facilities such as the TRIUMF Isotope Separator and Accelerator (ISAC). At ISAC the 8π spectrometer and its associated auxiliary detectors is optimize for β-decay studies while TIGRESS an array of segmented clover HPGe detectors has been designed for studies with accelerated beams. This paper gives a brief overview of these facilities and also presents recent examples of the diverse experimental program carried out at the 8π spectrometer.

X-ray absorption spectroscopy and neutron diffraction study of the perovskite-type rare-earth cobaltites

NASA Astrophysics Data System (ADS)

Sikolenko, V.; Efimova, E.; Franz, A.; Ritter, C.; Troyanchuk, I. O.; Karpinsky, D.; Zubavichus, Y.; Veligzhanin, A.; Tiutiunnikov, S. I.; Sazonov, A.; Efimov, V.

2018-05-01

Correlations between local and long-range structure distortions in the perovskite-type RE1-xSrxCoO3-δ (RE = La, Pr, Nd; x = 0.0 and 0.5) compounds have been studied at room temperature by extended X-ray absorption fine structure (EXAFS) at the Co K-edge and high-resolution neutron powder diffraction (NPD). The use of two complementary experimental techniques allowed us to explore the influence of the type of rare-earth element and strontium substitution on unusual behavior of static and dynamic features of both the Co-O bond lengths.

SARS E protein in phospholipid bilayers: an anomalous X-ray reflectivity study

NASA Astrophysics Data System (ADS)

Khattari, Z.; Brotons, G.; Arbely, E.; Arkin, I. T.; Metzger, T. H.; Salditt, T.

2005-02-01

We report on an anomalous X-ray reflectivity study to locate a labelled residue of a membrane protein with respect to the lipid bilayer. From such experiments, important constraints on the protein or peptide conformation can be derived. Specifically, our aim is to localize an iodine-labelled phenylalanine in the SARS E protein, incorporated in DMPC phospholipid bilayers, which are deposited in the form of thick multilamellar stacks on silicon surfaces. Here, we discuss the experimental aspects and the difficulties associated with the Fourier synthesis analysis that gives the electron density profile of the membranes.

Experiments with phase transitions at very high pressure. [compressed solidifed gases, semiconductors, superconductors, and molecular crystals

NASA Technical Reports Server (NTRS)

Spain, I. L.

1983-01-01

Diamond cells were constructed for use to 1 Mbar. A refrigerator for cooling diamond cells was adapted for studies between 15 and 300 K. A cryostat for superconductivity studies between 1.5 to 300 K was constructed. Optical equipment was constructed for fluorescence, transmission, and reflectance studies. X-ray equipment was adapted for use with diamond cells. Experimental techniques were developed for X-ray diffraction studies using synchrotron radiation. AC susceptibility techniques were developed for detecting superconducting transitions. The following materials were studied: compressed solidified gases (Xe, Ar), semiconductors (Ge, Si, GaAs), superconductors (Nb3Ge, Nb3Si, Nb3As, CuCl), molecular crystals (I).

[Experimental-morphologic study of bone tissue reaction to carbon-containing material implantation with initiated X-ray contrast property].

PubMed

Grigorian, A S; Nabiev, F Kh; Golovin, R V

2005-01-01

In experimental study on 15 rabbits (chinchilla) influence of titanium plates implanted lapped on adjacent tissues in the region of the lower jaw body (comparison group) and carbon material with added boron in the concentrations of 8 and 15% (the study group) was studied. Results of the experimental-morphological investigation show that carbon-based materials with boron addition (with its content 8 and 15%) did not impede adaptive rebuilding of bone tissues and in particular bone structure regeneration in the process of reactive rebuilding of the "maternal" bone. Moreover, as the result of reactive processes developing in osseous tissues after implantation of the tested materials their successful integration in surrounding tissue structures was detected.

Near Edge X-Ray Absorption and X-Ray Photoelectron Diffraction Studies of the Structural Environment of Ge-Si Systems

NASA Astrophysics Data System (ADS)

Castrucci, P.; Gunnella, R.; Pinto, N.; Bernardini, R.; de Crescenzi, M.; Sacchi, M.

Near edge X-ray absorption spectroscopy (XAS), X-ray photoelectron diffraction (XPD) and Auger electron diffraction (AED) are powerful techniques for the qualitative study of the structural and electronic properties of several systems. The recent development of a multiple scattering approach to simulating experimental spectra opened a friendly way to the study of structural environments of solids and surfaces. This article reviews recent X-ray absorption experiments using synchrotron radiation which were performed at Ge L edges and core level electron diffraction measurements obtained using a traditional X-ray source from Ge core levels for ultrathin Ge films deposited on silicon substrates. Thermodynamics and surface reconstruction have been found to play a crucial role in the first stages of Ge growth on Si(001) and Si(111) surfaces. Both techniques show the occurrence of intermixing processes even for room-temperature-grown Ge/Si(001) samples and give a straightforward measurement of the overlayer tetragonal distortion. The effects of Sb as a surfactant on the Ge/Si(001) interface have also been investigated. In this case, evidence of layer-by-layer growth of the fully strained Ge overlayer with a reduced intermixing is obtained when one monolayer of Sb is predeposited on the surface.

A deconvolution method for deriving the transit time spectrum for ultrasound propagation through cancellous bone replica models.

PubMed

Langton, Christian M; Wille, Marie-Luise; Flegg, Mark B

2014-04-01

The acceptance of broadband ultrasound attenuation for the assessment of osteoporosis suffers from a limited understanding of ultrasound wave propagation through cancellous bone. It has recently been proposed that the ultrasound wave propagation can be described by a concept of parallel sonic rays. This concept approximates the detected transmission signal to be the superposition of all sonic rays that travel directly from transmitting to receiving transducer. The transit time of each ray is defined by the proportion of bone and marrow propagated. An ultrasound transit time spectrum describes the proportion of sonic rays having a particular transit time, effectively describing lateral inhomogeneity of transit times over the surface of the receiving ultrasound transducer. The aim of this study was to provide a proof of concept that a transit time spectrum may be derived from digital deconvolution of input and output ultrasound signals. We have applied the active-set method deconvolution algorithm to determine the ultrasound transit time spectra in the three orthogonal directions of four cancellous bone replica samples and have compared experimental data with the prediction from the computer simulation. The agreement between experimental and predicted ultrasound transit time spectrum analyses derived from Bland-Altman analysis ranged from 92% to 99%, thereby supporting the concept of parallel sonic rays for ultrasound propagation in cancellous bone. In addition to further validation of the parallel sonic ray concept, this technique offers the opportunity to consider quantitative characterisation of the material and structural properties of cancellous bone, not previously available utilising ultrasound.

NASA to launch European cosmic ray experimental satellite

NASA Technical Reports Server (NTRS)

1975-01-01

Europe's first observatory satellite (COS-B) designed for extraterrestrial gamma radiation study and launched on a Delta rocket for the European Space Agency (ESA) by NASA is briefly described. The COS-B's mission objectives are given along with launch operations.

Carl Anderson and the Discovery of the Positron

Science.gov Websites

experimental piece of equipment of choice to study cosmic rays. ... Anderson designed and built his own cloud ? Top Some links on this page may take you to non-federal websites. Their policies may differ from this

TU-H-BRC-09: Validation of a Novel Therapeutic X-Ray Array Source and Collimation System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trovati, S; King, GJ; Loo, BW

2016-06-15

Purpose: We have experimentally characterized and simulated the dosimetric properties and spatial fidelity of a novel X-ray array source and collimation system called SPHINX that has the potential to generate complex intensity modulated X-ray beams by varying the electron beam intensity only, and without any moving parts like in multi-leaf collimators. Methods: We investigated the spatial fidelity and the X-ray performances of a SPHINX prototype in tungsten, using a Cyber Knife and the experimental high-energy electron beam line at XTA at SLAC National Laboratory. Dose distributions were recorded with gafchromic films, placed at the distal end of SPHINX and atmore » several depths in a solid water phantom. The geometry of SPHINX and of the experimental set-ups was also modeled in Monte Carlo (MC) simulations with the FLUKA code, used to reproduce the experimental results and, after validation, to predict and optimize the performance and design of the SPHINX. Results: The results indicate significant particle leakage through the channels during a single-channel irradiation for high incident energies, followed by a rapid decrease for energies of clinical interest. When the collimator channels are used as target, the photon production increases, however at expense of the beam size that is also enlarged. The illumination of all channels simultaneously shows a fairly even transmission of the beam. Conclusion: With the measurements we have verified the MC models and the uniformity of beam transmission through SPHINX, and we have evaluated the importance of particle leakage through adjacent channels. These results can be used to optimize SPHINX design through the validated MC simulations. Funding: Weston Havens Foundation, Office of the Dean of Medical School and Office of the Provost (Stanford University). Loo, Maxim, Borchard, Tantawi are co-founders of TibaRay Inc. Loo and Tantawi are TibaRay Inc. board members. Loo and Maxim received grants from Varian Medical Systems and RaySearch Laboratory.« less

X-Ray-induced Deuterium Enrichment of N-rich Organics in Protoplanetary Disks: An Experimental Investigation Using Synchrotron Light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavilan, Lisseth; Carrasco, Nathalie; Remusat, Laurent

The deuterium enrichment of organics in the interstellar medium, protoplanetary disks, and meteorites has been proposed to be the result of ionizing radiation. The goal of this study is to simulate and quantify the effects of soft X-rays (0.1–2 keV), an important component of stellar radiation fields illuminating protoplanetary disks, on the refractory organics present in the disks. We prepared tholins, nitrogen-rich organic analogs to solids found in several astrophysical environments, e.g., Titan’s atmosphere, cometary surfaces, and protoplanetary disks, via plasma deposition. Controlled irradiation experiments with soft X-rays at 0.5 and 1.3 keV were performed at the SEXTANTS beamline ofmore » the SOLEIL synchrotron, and were immediately followed by ex-situ infrared, Raman, and isotopic diagnostics. Infrared spectroscopy revealed the preferential loss of singly bonded groups (N–H, C–H, and R–N≡C) and the formation of sp{sup 3} carbon defects with signatures at ∼1250–1300 cm{sup −1}. Raman analysis revealed that, while the length of polyaromatic units is only slightly modified, the introduction of defects leads to structural amorphization. Finally, tholins were measured via secondary ion mass spectrometry to quantify the D, H, and C elemental abundances in the irradiated versus non-irradiated areas. Isotopic analysis revealed that significant D-enrichment is induced by X-ray irradiation. Our results are compared to previous experimental studies involving the thermal degradation and electron irradiation of organics. The penetration depth of soft X-rays in μ m-sized tholins leads to volume rather than surface modifications: lower-energy X-rays (0.5 keV) induce a larger D-enrichment than 1.3 keV X-rays, reaching a plateau for doses larger than 5 × 10{sup 27} eV cm{sup −3}. Synchrotron fluences fall within the expected soft X-ray fluences in protoplanetary disks, and thus provide evidence of a new non-thermal pathway to deuterium fractionation of organic matter.« less

Deflectometry using a Hartmann screen to measure tilt, decentering and focus errors in a spherical surface

NASA Astrophysics Data System (ADS)

Muñoz-Potosi, A. F.; Granados-Agustín, F.; Campos-García, M.; Valdivieso-González, L. G.; Percino-Zacarias, M. E.

2017-11-01

Among the various techniques that can be used to assess the quality of optical surfaces, deflectometry evaluates the reflection experienced by rays impinging on a surface whose topography is under study. We propose the use of a screen spatial filter to select rays from a light source. The screen must be placed at a distance shorter than the radius of curvature of the surface under study. The location of the screen depends on the exit pupil of the system and the caustic area. The reflected rays are measured using an observation plane/screen/CCD located beyond the point of convergence of the rays. To implement an experimental design of the proposed technique and determine the topography of the surface under study, it is necessary to measure tilt, decentering and focus errors caused by mechanical misalignment, which could influence the results of this technique but are not related to the quality of the surface. The aim of this study is to analyze an ideal spherical surface with known radius of curvature to identify the variations introduced by such misalignment errors.

Interaction of Radiation with Graphene Based Nanomaterials for Sensing Fissile Materials

DTIC Science & Technology

2016-03-01

about how ionizing radiation (gamma rays, neutrons ) and associated charged particles interact with nano-materials/structures based on graphene, which...various experimental tests of effect of light, X-rays, gamma-rays and neutrons on graphene & graphene FET) 2. What other organizations have been...knowledge about how ionizing radiation (gamma rays, neutrons ) and associated charged particles interact with nano- materials/structures based on graphene

Development of a mercuric iodide solid state spectrometer for X-ray astronomy

NASA Technical Reports Server (NTRS)

Vallerga, J.

1983-01-01

Mercuric iodide detectors, experimental development for astronomical use, X ray observations of the 1980 Cygnus X-1 High State, astronomical had X ray detectors in current use, detector development, balloon flight of large area (1500 sq cm) Phoswich detectors, had X ray telescope design, shielded mercuric iodide background measurement, Monte Carlo analysis, measurements with a shielded mercuric iodide detector are discussed.

Study of multilayered SiGe semiconductor structures by X-ray diffractometry, grazing-incidence X-ray reflectometry, and secondary-ion mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yunin, P. A., E-mail: yunin@ipmras.ru; Drozdov, Yu. N.; Drozdov, M. N.

2013-12-15

In this publication, we report the results of studying a multilayerd nonperiodic SiGe/Si structure by the methods of X-ray diffractometry, grazing-angle X-ray reflectometry, and secondary-ion mass spectrometry (SIMS). Special attention is paid to the processing of the component distribution profile using the SIMS method and to consideration of the most significant experimental distortions introduced by this method. A method for processing the measured composition distribution profile with subsequent consideration of the influence of matrix effects, variation in the etching rate, and remnants of ion sputtering is suggested. The results of such processing are compared with a structure model obtained uponmore » combined analysis of X-ray diffractometry and grazing-angle reflectometry data. Good agreement between the results is established. It is shown that the combined use of independent techniques makes it possible to improve the methods of secondary-ion mass spectrometry and grazing-incidence reflectometry as applied to an analysis of multilayered heteroepitaxial structures (to increase the accuracy and informativity of these methods)« less

Characterization and comparison of perezone with some analogues. Experimental and theoretical study

NASA Astrophysics Data System (ADS)

Escobedo-González, Rene Gerardo; Bahena, Luis; Arias Tellez, José Luis; Hinojosa Torres, Jaime; Ruvalcaba, Rene Miranda; Aceves-Hernández, Juan Manuel

2015-10-01

Perezone had been used for centuries in the traditional Mexican medicine, it is useful and a handful of illness. Perezone and other derivatives also present activity against certain lines of cancer, such as the myeloblastoid leukemia cell line K-562 and carcinoma cell lines (PC-3 and SKLU-1) with IC50 <10 μM. Perezone and isoperezone have shown the major cytotoxic potency. Characterization of perezone was carried out by UV-Visible, IR, DSC, TGA and powder X-ray diffraction, as well as docking studies using caspase-3 structures as receptors. Theoretical studies for optimizing the geometry of perezone were carried out and the results compared with values of single crystal X-ray diffraction. The experimental values of atomic distances, angles and dihedral angles are in good agreement with the theoretical values. Interaction of perezone with the cysteine catalytic site with the caspase-3 was found in the docking studies. A docking study of perezone, with horminone, thymoquinone and isoperezone as ligands and the protein apoptein, caspase-3 as receptor, was carried to demonstrate that the hindrance steric factor, chemical structure and the functional groups are important in the biological activity of these natural products. The docking score energetic values are in good agreement with the experimental cytotoxic results obtained from the experiments when perezone and analogues were studied in different types of cancer.

Comparison of different numerical treatments for x-ray phase tomography of soft tissue from differential phase projections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pelliccia, Daniele; Vaz, Raquel; Svalbe, Imants

X-ray imaging of soft tissue is made difficult by their low absorbance. The use of x-ray phase imaging and tomography can significantly enhance the detection of these tissues and several approaches have been proposed to this end. Methods such as analyzer-based imaging or grating interferometry produce differential phase projections that can be used to reconstruct the 3D distribution of the sample refractive index. We report on the quantitative comparison of three different methods to obtain x-ray phase tomography with filtered back-projection from differential phase projections in the presence of noise. The three procedures represent different numerical approaches to solve themore » same mathematical problem, namely phase retrieval and filtered back-projection. It is found that obtaining individual phase projections and subsequently applying a conventional filtered back-projection algorithm produces the best results for noisy experimental data, when compared with other procedures based on the Hilbert transform. The algorithms are tested on simulated phantom data with added noise and the predictions are confirmed by experimental data acquired using a grating interferometer. The experiment is performed on unstained adult zebrafish, an important model organism for biomedical studies. The method optimization described here allows resolution of weak soft tissue features, such as muscle fibers.« less

Intercomparison of Monte Carlo radiation transport codes to model TEPC response in low-energy neutron and gamma-ray fields.

PubMed

Ali, F; Waker, A J; Waller, E J

2014-10-01

Tissue-equivalent proportional counters (TEPC) can potentially be used as a portable and personal dosemeter in mixed neutron and gamma-ray fields, but what hinders this use is their typically large physical size. To formulate compact TEPC designs, the use of a Monte Carlo transport code is necessary to predict the performance of compact designs in these fields. To perform this modelling, three candidate codes were assessed: MCNPX 2.7.E, FLUKA 2011.2 and PHITS 2.24. In each code, benchmark simulations were performed involving the irradiation of a 5-in. TEPC with monoenergetic neutron fields and a 4-in. wall-less TEPC with monoenergetic gamma-ray fields. The frequency and dose mean lineal energies and dose distributions calculated from each code were compared with experimentally determined data. For the neutron benchmark simulations, PHITS produces data closest to the experimental values and for the gamma-ray benchmark simulations, FLUKA yields data closest to the experimentally determined quantities. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A comparison between EGS4 and MCNP computer modeling of an in vivo X-ray fluorescence system.

PubMed

Al-Ghorabie, F H; Natto, S S; Al-Lyhiani, S H

2001-03-01

The Monte Carlo computer codes EGS4 and MCNP were used to develop a theoretical model of a 180 degrees geometry in vivo X-ray fluorescence system for the measurement of platinum concentration in head and neck tumors. The model included specification of the photon source, collimators, phantoms and detector. Theoretical results were compared and evaluated against X-ray fluorescence data obtained experimentally from an existing system developed by the Swansea In Vivo Analysis and Cancer Research Group. The EGS4 results agreed well with the MCNP results. However, agreement between the measured spectral shape obtained using the experimental X-ray fluorescence system and the simulated spectral shape obtained using the two Monte Carlo codes was relatively poor. The main reason for the disagreement between the results arises from the basic assumptions which the two codes used in their calculations. Both codes assume a "free" electron model for Compton interactions. This assumption will underestimate the results and invalidates any predicted and experimental spectra when compared with each other.

Validation of columnar CsI x-ray detector responses obtained with hybridMANTIS, a CPU-GPU Monte Carlo code for coupled x-ray, electron, and optical transport.

PubMed

Sharma, Diksha; Badano, Aldo

2013-03-01

hybridMANTIS is a Monte Carlo package for modeling indirect x-ray imagers using columnar geometry based on a hybrid concept that maximizes the utilization of available CPU and graphics processing unit processors in a workstation. The authors compare hybridMANTIS x-ray response simulations to previously published MANTIS and experimental data for four cesium iodide scintillator screens. These screens have a variety of reflective and absorptive surfaces with different thicknesses. The authors analyze hybridMANTIS results in terms of modulation transfer function and calculate the root mean square difference and Swank factors from simulated and experimental results. The comparison suggests that hybridMANTIS better matches the experimental data as compared to MANTIS, especially at high spatial frequencies and for the thicker screens. hybridMANTIS simulations are much faster than MANTIS with speed-ups up to 5260. hybridMANTIS is a useful tool for improved description and optimization of image acquisition stages in medical imaging systems and for modeling the forward problem in iterative reconstruction algorithms.

Transition metal atomic multiplets in the ligand K-edge x-ray absorption spectra and multiple oxidation states in the L2,3 emission of strongly correlated compounds

NASA Astrophysics Data System (ADS)

Jiménez-Mier, J.; Olalde-Velasco, P.; Yang, W.-L.; Denlinger, J.

2014-07-01

We present results that show that atomic multiplet ligand field calculations are in very good agreement with experimental x-ray absorption spectra at the L2,3 edge of transition metal (TM) di-fluorides (MF2, MCrCu). For chromium more than one TM oxidation state is needed to achieve such an agreement. We also show that signature of the TM atomic multiplet can be found at the pre-edge of the fluorine K-edge x-ray absorption spectra. TM atomic multiplet ligand field calculations with a structureless core hole show good agreement with the observed pre-edges in the experimental fluorine absorption spectra. Preliminary results for the comparison between calculated and experimental resonant x-ray emission spectra for nominal CrF2 with more than one oxidation state indicate the presence of three chromium oxidation states in the bulk.

Synchrotron hard X-ray imaging of shock-compressed metal powders

NASA Astrophysics Data System (ADS)

Rutherford, Michael E.; Chapman, David J.; Collinson, Mark A.; Jones, David R.; Music, Jasmina; Stafford, Samuel J. P.; Tear, Gareth R.; White, Thomas G.; Winters, John B. R.; Drakopoulos, Michael; Eakins, Daniel E.

2015-06-01

This poster will present the application of a new, high-energy (50 to 250 keV) synchrotron X-ray radiography technique to the study of shock-compressed granular materials. Following plate-impact loading, transmission radiography was used to quantitatively observe the compaction and release processes in a range of high-Z metal powders (e.g. Fe, Ni, Cu). By comparing the predictions of 3D numerical models initialized from X-ray tomograms-captured prior to loading-with experimental results, this research represents a new approach to refining mesoscopic compaction models. The authors gratefully acknowledge the ongoing support of Imperial College London, EPSRC, STFC and the Diamond Light Source, and AWE Plc.

Development of a high resolution liquid xenon imaging chamber for gamma-ray astronomy

NASA Technical Reports Server (NTRS)

Aprile, Elena

1991-01-01

The objective was to develop the technology of liquid xenon (LXe) detectors for spectroscopy and imaging of gamma rays from astrophysical sources emitting in the low to medium energy regime. In particular, the technical challenges and the physical processes relevant to the realization of the LXe detector operated as a Time Projection Chamber (TPC) were addressed and studied. Experimental results were obtained on the following topics: (1) long distance drift of free electrons in LXe (purity); (2) scintillation light yield for electrons and alphas in LXe (triggering); and (3) ionization yield for electrons and gamma rays in LXe (energy resolution). The major results from the investigations are summarized.

Thin film CdTe based neutron detectors with high thermal neutron efficiency and gamma rejection for security applications

NASA Astrophysics Data System (ADS)

Smith, L.; Murphy, J. W.; Kim, J.; Rozhdestvenskyy, S.; Mejia, I.; Park, H.; Allee, D. R.; Quevedo-Lopez, M.; Gnade, B.

2016-12-01

Solid-state neutron detectors offer an alternative to 3He based detectors, but suffer from limited neutron efficiencies that make their use in security applications impractical. Solid-state neutron detectors based on single crystal silicon also have relatively high gamma-ray efficiencies that lead to false positives. Thin film polycrystalline CdTe based detectors require less complex processing with significantly lower gamma-ray efficiencies. Advanced geometries can also be implemented to achieve high thermal neutron efficiencies competitive with silicon based technology. This study evaluates these strategies by simulation and experimentation and demonstrates an approach to achieve >10% intrinsic efficiency with <10-6 gamma-ray efficiency.

Water detection at the moon, Mars and comets with a combined neutron gamma ray instrument

NASA Technical Reports Server (NTRS)

Metzger, Albert E.; Haines, Eldon L.

1991-01-01

Measuring the fluxes of thermal and epithermal neutrons at a planetary object in conjunction with gamma-ray spectroscopic observations will provide information about the chemical composition of the surface which is less model dependent than the gamma ray measurements by themselves. Researchers devised a passive neutron detector for this purpose. An experimental model was designed and built. Three variables provided the basis for a set of experiments: thickness of the Sm and B layers, the presence or absence of the ACS, and the position of the source relative to the PND's cylindrical axis. Experimental results are given.

Wavelength calibration of x-ray imaging crystal spectrometer on Joint Texas Experimental Tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Jin, W.

2014-11-15

The wavelength calibration of x-ray imaging crystal spectrometer is a key issue for the measurements of plasma rotation. For the lack of available standard radiation source near 3.95 Å and there is no other diagnostics to measure the core rotation for inter-calibration, an indirect method by using tokamak plasma itself has been applied on joint Texas experimental tokamak. It is found that the core toroidal rotation velocity is not zero during locked mode phase. This is consistent with the observation of small oscillations on soft x-ray signals and electron cyclotron emission during locked-mode phase.

X-ray tests of a microchannel plate detector and amorphous silicon pixel array readout for neutron radiography

NASA Astrophysics Data System (ADS)

Ambrosi, R. M.; Street, R.; Feller, B.; Fraser, G. W.; Watterson, J. I. W.; Lanza, R. C.; Dowson, J.; Ross, D.; Martindale, A.; Abbey, A. F.; Vernon, D.

2007-03-01

High-performance large area imaging detectors for fast neutrons in the 5-14 MeV energy range do not exist at present. The aim of this project is to combine microchannel plates or MCPs (or similar electron multiplication structures) traditionally used in image intensifiers and X-ray detectors with amorphous silicon (a-Si) pixel arrays to produce a composite converter and intensifier position sensitive imaging system. This detector will provide an order of magnitude improvement in image resolution when compared with current millimetre resolution limits obtained using phosphor or scintillator-based hydrogen rich converters. In this study we present the results of the initial experimental evaluation of the prototype system. This study was carried out using a medical X-ray source for the proof of concept tests, the next phase will involve neutron imaging tests. The hybrid detector described in this study is a unique development and paves the way for large area position sensitive detectors consisting of MCP or microsphere plate detectors and a-Si or polysilicon pixel arrays. Applications include neutron and X-ray imaging for terrestrial applications. The technology could be extended to space instrumentation for X-ray astronomy.

[The effect of osteogenic inducer on healing of tooth extraction sockets].

PubMed

Chen, Junliang; Shan, Chuncheng; He, Yun; Xia, Delin

2012-06-01

To study the effect of osteogenic inducer (dexamethasone, beta-sodium glycerophosphate and Vitamin C) carried by gelatin sponge on healing and remodeling of tooth extraction sockets. Fifty rabbits were selected. After extracting the first premolars of bilateral maxillary, the right side tooth extraction sockets were filled with gelatin sponge containing osteogenic inducer as experimental side, tooth extraction sockets on left side were filled with gelatin sponge as control. Every ten rabbits were executed at the end of 1, 2, 4, 8, 12 weeks after tooth extraction. Bone density was measured through digital X-ray images. The specimens were examined by histology. The absorption height of alveolar bone at 12 weeks was measured. X-ray measurement showed that the bone density of experimental side was higher than that of control side at 2, 4, 8, 12 weeks, the difference had statistical significance (P<0.01). The histology examination showed that new bone formation in tooth extraction sockets of experimental side was earlier than that in control side. The absorptional height of alveolar bone had significant difference between experimental side and control side (P<0.01), of which experimental side was less. Filling the osteogenic inducer in tooth extraction sockets can promote the healing and new bone formation and prevent from alveolar bone absorption.

Wide-Angle X-Ray Scattering and Solid-State Nuclear Magnetic Resonance Data Combined to Test Models for Cellulose Microfibrils in Mung Bean Cell Walls1

PubMed Central

Newman, Roger H.; Hill, Stefan J.; Harris, Philip J.

2013-01-01

A synchrotron wide-angle x-ray scattering study of mung bean (Vigna radiata) primary cell walls was combined with published solid-state nuclear magnetic resonance data to test models for packing of (1→4)-β-glucan chains in cellulose microfibrils. Computer-simulated peak shapes, calculated for 36-chain microfibrils with perfect order or uncorrelated disorder, were sharper than those in the experimental diffractogram. Introducing correlated disorder into the models broaden the simulated peaks but only when the disorder was increased to unrealistic magnitudes. Computer-simulated diffractograms, calculated for 24- and 18-chain models, showed good fits to experimental data. Particularly good fits to both x-ray and nuclear magnetic resonance data were obtained for collections of 18-chain models with mixed cross-sectional shapes and occasional twinning. Synthesis of 18-chain microfibrils is consistent with a model for cellulose-synthesizing complexes in which three cellulose synthase polypeptides form a particle and six particles form a rosette. PMID:24154621

Monte Carlo analysis of the oxygen knock-on effects induced by synchrotron x-ray radiation in the B i2S r2CaC u2O8 +δ superconductor

NASA Astrophysics Data System (ADS)

Torsello, Daniele; Mino, Lorenzo; Bonino, Valentina; Agostino, Angelo; Operti, Lorenza; Borfecchia, Elisa; Vittone, Ettore; Lamberti, Carlo; Truccato, Marco

2018-01-01

We investigate the microscopic mechanism responsible for the change of macroscopic electrical properties of the B i2S r2CaC u2O8 +δ high-temperature superconductor induced by intense synchrotron hard x-ray beams. The possible effects of secondary electrons on the oxygen content via the knock-on interaction are studied by Monte Carlo simulations. The change in the oxygen content expected from the knock-on model is computed convoluting the fluence of photogenerated electrons in the material with the Seitz-Koehler cross section. This approach has been adopted to analyze several experimental irradiation sessions with increasing x-ray fluences. A close comparison between the expected variations in oxygen content and the experimental results allows determining the irradiation regime in which the knock-on mechanism can satisfactorily explain the observed changes. Finally, we estimate the threshold displacement energy of loosely bound oxygen atoms in this material Td=0 .15-0.01+0.025eV .

Breakup phenomena of a coaxial jet in the non-dilute region using real-time X-ray radiography

NASA Astrophysics Data System (ADS)

Cheung, F. B.; Kuo, K. K.; Woodward, R. D.; Garner, K. N.

1990-07-01

An innovative approach to the investigation of liquid jet breakup processes in the near-injector region has been developed to overcome the experimental difficulties associated with optically opaque, dense sprays. Real-time X-ray radiography (RTR) has been employed to observe the inner structure and breakup phenomena of coaxial jets. In the atomizing regime, droplets much smaller than the exit diameter are formed beginning essentially at the injector exit. Through the use of RTR, the instantaneous contour of the liquid core was visualized. Experimental results consist of controlled-exposure digital video images of the liquid jet breakup process. Time-averaged video images have also been recorded for comparison. A digital image processing system is used to analyze the recorded images by creating radiance level distributions of the jet. A rudimentary method for deducing intact-liquid-core length has been suggested. The technique of real-time X-ray radiography has been shown to be a viable approach to the study of the breakup processes of high-speed liquid jets.

Theoretical and experimental determination of K - and L -shell x-ray relaxation parameters in Ni

NASA Astrophysics Data System (ADS)

Guerra, M.; Sampaio, J. M.; Parente, F.; Indelicato, P.; Hönicke, P.; Müller, M.; Beckhoff, B.; Marques, J. P.; Santos, J. P.

2018-04-01

Fluorescence yields (FY) for the Ni K and L shells were determined by a theoretical and an experimental group within the framework of the International Initiative on X-ray Fundamental Parameters (FPs) collaboration. Coster-Kronig (CK) parameters were also measured for the L shell of Ni. Theoretical calculations of the same parameters were performed using the Dirac-Fock method, including relativistic and QED corrections. The experimental values for the FY and CK were determined at the PTB laboratory in the synchrotron radiation facility BESSY II, Berlin, Germany, and are compared to the corresponding calculated values.

Synchrotron-based soft X-ray spectroscopic studies of the electronic structure of organic semiconducting molecules

NASA Astrophysics Data System (ADS)

Demasi, Alexander

Organic molecules have been the subject of many scientific studies due to their potential for use in a new generation of optoelectronic and semiconducting devices, such as organic photovoltaics and organic light emitting diodes. These studies are motivated by the fact that organic semiconductor devices have several advantages over traditional inorganic semiconductor devices. Unlike inorganic semiconductors, where the electronic properties are a result of the deliberate introduction of dopants to the material, the properties of organic semiconductors are often intrinsic to the molecules themselves. As a result, organic semiconductor devices are frequently less susceptible to contamination by impurities than their inorganic counterparts, which results in the relatively lower cost of producing such devices. Accurate experimental determination of the bulk and surface electronic structure of organic semiconductors is a prerequisite in developing a comprehensive understanding of such materials. The organic materials studied in this thesis were N,N-Ethylene-bis(1,1,1trifluoropentane-2,4-dioneiminato)-copper(ii) (abbreviated Cu-TFAC), aluminum tris-8hydroxyquinoline (A1g3), lithium quinolate (Liq), tetracyanoquinodimethane (TCNQ), and tetrafluorotetracyanoquinodimethane (F4TCNQ). The electronic structures of these materials were measured with several synchrotron-based x-ray spectroscopies. X-ray photoemission spectroscopy was used to measure the occupied total density of states and the core-level states of the aforementioned materials. X-ray absorption spectroscopy (XAS) was used to probe the element-specific unoccupied partial density of states (PDOS); its angle-resolved variant was used to measure the orientation of the molecules in a film and, in some circumstances, to gauge the extent of an organic film's crystallinity. Most notably, x-ray emission spectroscopy (XES) measures the element- specific occupied PDOS and, when aided by XAS, resonant XES can additionally be used to probe the electronic structure of individual atomic sites within a molecule. Most of the results in this thesis are accompanied by the results of electronic structure calculations determined with density functional theory (DFT). DFT is a useful aid in interpreting the results of the x-ray spectroscopies employed. The experimental results, combined with DFT calculations, provide a wealth of information regarding the electronic structures of these organic materials. v

Photo-Darkening Kinetics and Structural Anisotropic Modifications in the Chalcogenide Glass Arsenic Trisulfide: a Study of Kinetic X-Ray Absorption Spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Jay Min

1990-08-01

The purpose of the study is to investigate the mechanisms involved with photo-induced atomic structural modifications in the chalcogenide glass As_2 S_3. This glass exhibits the reversible effects of photo-darkening followed by thermal bleaching. We observed the time behavior of photo-induced properties under the influence of linearly polarized band -gap light. In a macroscopic optical investigation, we monitor optical changes in the photo-darkening process, and in a local structural probe we study kinetic (or time -resolved dispersive) x-ray absorption spectroscopy. Our observations center on kinetic phenomena and structural modifications induced by polarized excitation of lone-pair orbitals in the chalcogenide glass. Experimental results include the following observations: (i) The polarity of the optically induced anisotropy is critically dependent on the intensity and the polarization of the band-gap irradiation beam. (ii) The near edge peak height in x-ray absorption spectra shows subtle but sensitive change during the photo-darkening process. (iii) Photon intensity dependent dichroic kinetics reflect a connection between the optically probed macroscopic property and the x-ray probed local anisotropic structure. Analysis of the x-ray absorption results includes a computer simulation of the polarized absorption spectra. These results suggest that specific structural units tend to orient themselves with respect to the photon polarization. A substantial part of the analysis involves a major effort in dealing with the x-ray kinetic data manipulation and the experimental difficulties caused by a synchrotron instability problem. Based on our observations, we propose a possible mechanism for the observed photo-structural modifications. Through a model of computer relaxed photo-darkening kinetics, we support the notion that a twisting of a specific intermediate range order structure is responsible for local directional variations and global network distortions. In the course of this study, we refine knowledge of intermediate range order structural configurations and the bistabilities related to these configurations. The importance of the lone-pair orbital interactions in the chalcogenide glassy network is underscored.

Experimental Constraints on γ-Ray Pulsar Gap Models and the Pulsar GeV to Pulsar Wind Nebula TeV Connection

NASA Astrophysics Data System (ADS)

Abeysekara, A. U.; Linnemann, J. T.

2015-05-01

The pulsar emission mechanism in the gamma ray energy band is poorly understood. Currently, there are several models under discussion in the pulsar community. These models can be constrained by studying the collective properties of a sample of pulsars, which became possible with the large sample of gamma ray pulsars discovered by the Fermi Large Area Telescope. In this paper we develop a new experimental multi-wavelength technique to determine the beaming factor ≤ft( {{f}{Ω }} \\right) dependance on spin-down luminosity of a set of GeV pulsars. This technique requires three input parameters: pulsar spin-down luminosity, pulsar phase-averaged GeV flux, and TeV or X-ray flux from the associated pulsar wind nebula (PWN). The analysis presented in this paper uses the PWN TeV flux measurements to study the correlation between {{f}{Ω }} and \\dot{E}. The measured correlation has some features that favor the Outer Gap model over the Polar Cap, Slot Gap, and One Pole Caustic models for pulsar emission in the energy range of 0.1-100 GeV, but one must keep in mind that these simulated models failed to explain many of the most important pulsar population characteristics. A tight correlation between the pulsar GeV emission and PWN TeV emission was also observed, which suggests the possibility of a linear relationship between the two emission mechanisms. In this paper we also discuss a possible mechanism to explain this correlation.

X-ray Diffraction Studies of the Structure and Thermochemistry of Alkaline-Earth Oxide-Coated Thermionic Cathodes

NASA Technical Reports Server (NTRS)

Karikari, E. K.; Bassey, E.; Wintucky, Edwin G.

1998-01-01

NASA LeRC has a broad, active cathode technology development program in which both experimental and theoretical studies are being employed to further development of thermionic cathodes for use as electron sources in vacuum devices for communications and other space applications. One important type of thermionic cathode under development is the alkaline-earth oxide-coated (BaO, SrO, CaO) cathode. Significant improvements in the emission characteristics of this cathode have been obtained through modification of the chemical composition and morphology of the oxide coating, with the best result thus far coming from the addition of In2O3 and Sc2O3. Whereas the In2O3 produces a finer, more uniform particle structure, the exact chemical state and role of the Sc2O3 in the emission enhancement is unknown. The purpose of this cooperative agreement is to combine the studies of the surface chemistry and electron emission at NASA LeRC of chemically modified oxide coatings with a study of the thermochemistry and crystal structure using X-ray diffraction equipment and expertise at Clark Atlanta University (CAU). The study at CAU is intended to provide the description and understanding of the structure and thermochemistry needed for further improvement and optimization of the modified coatings. A description of the experimental procedure, preliminary X-ray diffraction test results, together with the design of an ultrahigh vacuum chamber necessary for high temperature thermochemistry studies will be presented.

Experimental evaluation of radiosity for room sound-field prediction.

PubMed

Hodgson, Murray; Nosal, Eva-Marie

2006-08-01

An acoustical radiosity model was evaluated for how it performs in predicting real room sound fields. This was done by comparing radiosity predictions with experimental results for three existing rooms--a squash court, a classroom, and an office. Radiosity predictions were also compared with those by ray tracing--a "reference" prediction model--for both specular and diffuse surface reflection. Comparisons were made for detailed and discretized echograms, sound-decay curves, sound-propagation curves, and the variations with frequency of four room-acoustical parameters--EDT, RT, D50, and C80. In general, radiosity and diffuse ray tracing gave very similar predictions. Predictions by specular ray tracing were often very different. Radiosity agreed well with experiment in some cases, less well in others. Definitive conclusions regarding the accuracy with which the rooms were modeled, or the accuracy of the radiosity approach, were difficult to draw. The results suggest that radiosity predicts room sound fields with some accuracy, at least as well as diffuse ray tracing and, in general, better than specular ray tracing. The predictions of detailed echograms are less accurate, those of derived room-acoustical parameters more accurate. The results underline the need to develop experimental methods for accurately characterizing the absorptive and reflective characteristics of room surfaces, possible including phase.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sisniega, A.; Vaquero, J. J., E-mail: juanjose.vaquero@uc3m.es; Instituto de Investigación Sanitaria Gregorio Marañón, Madrid ES28007

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, modifiedmore » 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.« less

On the origin of cosmic rays. [gamma rays and supernova remnants

NASA Technical Reports Server (NTRS)

Stecker, F. W.

1975-01-01

Using Recent surveys of molecular clouds and gamma rays in the galaxy, it is possible to determine the distribution of 1 to 10 GeV cosmic-ray nucleons in the galaxy. This distribution appears to be identical to the supernova remnant distribution to within experimental error and provides strong support for the hypothesis that supernovae produce most of the observed cosmic rays. This distribution resembles that of OB associations of average age approximately 30 million years suggesting that cosmic rays are produced by population objects about 30 million years after their birth.

Why LiFePO4 is a safe battery electrode: Coulomb repulsion induced electron-state reshuffling upon lithiation.

PubMed

Liu, Xiaosong; Wang, Yung Jui; Barbiellini, Bernardo; Hafiz, Hasnain; Basak, Susmita; Liu, Jun; Richardson, Thomas; Shu, Guojiun; Chou, Fangcheng; Weng, Tsu-Chien; Nordlund, Dennis; Sokaras, Dimosthenis; Moritz, Brian; Devereaux, Thomas P; Qiao, Ruimin; Chuang, Yi-De; Bansil, Arun; Hussain, Zahid; Yang, Wanli

2015-10-21

LiFePO4 is a battery cathode material with high safety standards due to its unique electronic structure. We performed systematic experimental and theoretical studies based on soft X-ray emission, absorption, and hard X-ray Raman spectroscopy of LixFePO4 nanoparticles and single crystals. The results clearly show a non-rigid electron-state reconfiguration of both the occupied and unoccupied Fe-3d and O-2p states during the (de)lithiation process. We focus on the energy configurations of the occupied states of LiFePO4 and the unoccupied states of FePO4, which are the critical states where electrons are removed and injected during the charge and discharge process, respectively. In LiFePO4, the soft X-ray emission spectroscopy shows that, due to the Coulomb repulsion effect, the occupied Fe-3d states with the minority spin sit close to the Fermi level. In FePO4, the soft X-ray absorption and hard X-ray Raman spectroscopy show that the unoccupied Fe-3d states again sit close to the Fermi level. These critical 3d electron state configurations are consistent with the calculations based on modified Becke and Johnson potentials GGA+U (MBJGGA+U) framework, which improves the overall lineshape prediction compared with the conventionally used GGA+U method. The combined experimental and theoretical studies show that the non-rigid electron state reshuffling guarantees the stability of oxygen during the redox reaction throughout the charge and discharge process of LiFePO4 electrodes, leading to the intrinsic safe performance of the electrodes.

Validation of the mean radiant temperature simulated by the RayMan software in urban environments.

PubMed

Lee, Hyunjung; Mayer, Helmut

2016-11-01

The RayMan software is worldwide applied in investigations on different issues in human-biometeorology. However, only the simulated mean radiant temperature (T mrt ) has been validated so far in a few case studies. They are based on T mrt values, which were experimentally determined in urban environments by use of a globe thermometer or applying the six-directional method. This study analyses previous T mrt validations in a comparative manner. Their results are extended by a recent validation of T mrt in an urban micro-environment in Freiburg (southwest Germany), which can be regarded as relatively heterogeneous due to different shading intensities by tree crowns. In addition, a validation of the physiologically equivalent temperature (PET) simulated by RayMan is conducted for the first time. The validations are based on experimentally determined T mrt and PET values, which were calculated from measured meteorological variables in the daytime of a clear-sky summer day. In total, the validation results show that RayMan is capable of simulating T mrt satisfactorily under relatively homogeneous site conditions. However, the inaccuracy of simulated T mrt is increasing with lower sun elevation and growing heterogeneity of the simulation site. As T mrt represents the meteorological variable that mostly governs PET in the daytime of clear-sky summer days, the accuracy of simulated T mrt is mainly responsible for the accuracy of simulated PET. The T mrt validations result in some recommendations, which concern an update of physical principles applied in the RayMan software to simulate the short- and long-wave radiant flux densities, especially from vertical building walls and tree crowns.

Study on the influence of X-ray tube spectral distribution on the analysis of bulk samples and thin films: Fundamental parameters method and theoretical coefficient algorithms

NASA Astrophysics Data System (ADS)

Sitko, Rafał

2008-11-01

Knowledge of X-ray tube spectral distribution is necessary in theoretical methods of matrix correction, i.e. in both fundamental parameter (FP) methods and theoretical influence coefficient algorithms. Thus, the influence of X-ray tube distribution on the accuracy of the analysis of thin films and bulk samples is presented. The calculations are performed using experimental X-ray tube spectra taken from the literature and theoretical X-ray tube spectra evaluated by three different algorithms proposed by Pella et al. (X-Ray Spectrom. 14 (1985) 125-135), Ebel (X-Ray Spectrom. 28 (1999) 255-266), and Finkelshtein and Pavlova (X-Ray Spectrom. 28 (1999) 27-32). In this study, Fe-Cr-Ni system is selected as an example and the calculations are performed for X-ray tubes commonly applied in X-ray fluorescence analysis (XRF), i.e., Cr, Mo, Rh and W. The influence of X-ray tube spectra on FP analysis is evaluated when quantification is performed using various types of calibration samples. FP analysis of bulk samples is performed using pure-element bulk standards and multielement bulk standards similar to the analyzed material, whereas for FP analysis of thin films, the bulk and thin pure-element standards are used. For the evaluation of the influence of X-ray tube spectra on XRF analysis performed by theoretical influence coefficient methods, two algorithms for bulk samples are selected, i.e. Claisse-Quintin (Can. Spectrosc. 12 (1967) 129-134) and COLA algorithms (G.R. Lachance, Paper Presented at the International Conference on Industrial Inorganic Elemental Analysis, Metz, France, June 3, 1981) and two algorithms (constant and linear coefficients) for thin films recently proposed by Sitko (X-Ray Spectrom. 37 (2008) 265-272).

Observations of Ball-Lightning-Like Plasmoids Ejected from Silicon by Localized Microwaves

PubMed Central

Meir, Yehuda; Jerby, Eli; Barkay, Zahava; Ashkenazi, Dana; Mitchell, James Brian; Narayanan, Theyencheri; Eliaz, Noam; LeGarrec, Jean-Luc; Sztucki, Michael; Meshcheryakov, Oleg

2013-01-01

This paper presents experimental characterization of plasmoids (fireballs) obtained by directing localized microwave power (<1 kW at 2.45 GHz) onto a silicon-based substrate in a microwave cavity. The plasmoid emerges up from the hotspot created in the solid substrate into the air within the microwave cavity. The experimental diagnostics employed for the fireball characterization in this study include measurements of microwave scattering, optical spectroscopy, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Various characteristics of these plasmoids as dusty plasma are drawn by a theoretical analysis of the experimental observations. Aggregations of dust particles within the plasmoid are detected at nanometer and micrometer scales by both in-situ SAXS and ex-situ SEM measurements. The resemblance of these plasmoids to the natural ball-lightning (BL) phenomenon is discussed with regard to silicon nano-particle clustering and formation of slowly-oxidized silicon micro-spheres within the BL. Potential applications and practical derivatives of this study (e.g., direct conversion of solids to powders, material identification by breakdown spectroscopy (MIBS), thermite ignition, and combustion) are discussed. PMID:28788315

M(II)-dipyridylamide-based coordination frameworks (M=Mn, Co, Ni): Structural transformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tzeng, Biing-Chiau; Selvam, TamilSelvi; Tsai, Miao-Hsin

2016-11-15

A series of 1-D double-zigzag (([M(papx){sub 2}(H{sub 2}O){sub 2}](ClO{sub 4}){sub 2}){sub n}; M=Mn, x=s (1), x=o (3); M=Co, x=s (4), x=o (5); M=Ni, x=s (6), x=o (7)) and 2-D polyrotaxane ([Mn(paps){sub 2}(ClO{sub 4}){sub 2}]{sub n} (2)) frameworks were synthesized by reactions of M(ClO{sub 4}){sub 2} (M=Mn, Co, and Ni) with papx (paps, N,N’-bis(pyridylcarbonyl)-4,4’-diaminodiphenylthioether; papo, N,N’-bis(pyridylcarbonyl)-4,4’-diaminodiphenyl ether), which have been isolated and structurally characterized by X-ray diffraction. Based on powder X-ray diffraction (PXRD) experiments, heating the double-zigzag frameworks underwent structural transformation to give the respective polyrotaxane ones. Moreover, grinding the solid samples of the respective polyrotaxanes in the presence of moisturemore » also resulted in the total conversion to the original double-zigzag frameworks. In this study, we have successfully extended studies to Mn{sup II}, Co{sup II}, and Ni{sup II} frameworks from the previous Zn{sup II}, Cd{sup II}, and Cu{sup II} ones, and interestingly such structural transformation is able to be proven experimentally by powder and single-crystal X-ray diffraction studies as well. - Graphical abstract: 1-D double-zigzag and 2-D polyrotaxane frameworks of M(II)-papx (x=s, o; M=Mn, Co, Ni) frameworks can be interconverted by heating and grinding in the presence of moiture, and such structural transformation has be proven experimentally by powder and single-crystal X-ray diffraction studies.« less

Background radiation in inelastic X-ray scattering and X-ray emission spectroscopy. A study for Johann-type spectrometers

NASA Astrophysics Data System (ADS)

Paredes Mellone, O. A.; Bianco, L. M.; Ceppi, S. A.; Goncalves Honnicke, M.; Stutz, G. E.

2018-06-01

A study of the background radiation in inelastic X-ray scattering (IXS) and X-ray emission spectroscopy (XES) based on an analytical model is presented. The calculation model considers spurious radiation originated from elastic and inelastic scattering processes along the beam paths of a Johann-type spectrometer. The dependence of the background radiation intensity on the medium of the beam paths (air and helium), analysed energy and radius of the Rowland circle was studied. The present study shows that both for IXS and XES experiments the background radiation is dominated by spurious radiation owing to scattering processes along the sample-analyser beam path. For IXS experiments the spectral distribution of the main component of the background radiation shows a weak linear dependence on the energy for the most cases. In the case of XES, a strong non-linear behaviour of the background radiation intensity was predicted for energy analysis very close to the backdiffraction condition, with a rapid increase in intensity as the analyser Bragg angle approaches π / 2. The contribution of the analyser-detector beam path is significantly weaker and resembles the spectral distribution of the measured spectra. Present results show that for usual experimental conditions no appreciable structures are introduced by the background radiation into the measured spectra, both in IXS and XES experiments. The usefulness of properly calculating the background profile is demonstrated in a background subtraction procedure for a real experimental situation. The calculation model was able to simulate with high accuracy the energy dependence of the background radiation intensity measured in a particular XES experiment with air beam paths.

Site partitioning of Cr3+ in the trichroic alexandrite BeAl2O4:Cr3+ crystal: contribution from x-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Bordage, Amélie; Rossano, Stéphanie; Horn, Adolf Heinrich; Fuchs, Yves

2012-06-01

X-ray absorption spectroscopy measurements at the Cr K-edge of a trichroic crystal of alexandrite BeAl2O4:Cr3+ for different orientations of the crystal with respect to the polarization and direction of the x-ray incident beam have been performed. Analysis of the experimental spectra with the help of first-principles calculations of x-ray absorption spectra allowed us to estimate the proportion of chromium Cr3+ cations among the two different octahedral sites of the alexandrite structure (70% in the Cs site-30% in the Ci site). The methodology presented in this work opens up new possibilities in the field of mineralogy for the study of complex minerals containing several sites potentially occupied by several transition elements or for solid solutions.

Determination of 200 °C Isothermal Section of Al-Ag-Ga Phase Diagram by Microanalysis, X-ray Diffraction, Hardness and Electrical Conductivity Measurements

NASA Astrophysics Data System (ADS)

Premović, Milena; Tomović, Milica; Minić, Duško; Manasijević, Dragan; Živković, Dragana; Ćosović, Vladan; Grković, Vladan; Đorđević, Aleksandar

2017-04-01

Ternary Al-Ag-Ga system at 200 °C was experimentally and thermodynamically assessed. Isothermal section was extrapolated using optimized thermodynamic parameters for constitutive binary systems. Microstructure and phase composition of the selected alloy samples were analyzed using light microscopy, scanning electron microscopy combined with energy-dispersive spectrometry and x-ray powder diffraction technique. The obtained experimental results were found to be in a close agreement with the predicted phase equilibria. Hardness and electrical conductivity of the alloy samples from four vertical sections Al-Ag80Ga20, Al-Ag60Ga40, Ag-Al80Ga20 and Ag-Al60Ga40 of the ternary Al-Ag-Ga system at 200 °C were experimentally determined using Brinell method and eddy current measurements. Additionally, hardness of the individual phases present in the microstructure of the studied alloy samples was determined using Vickers microhardness test. Based on experimentally obtained results, isolines of Brinell hardness and electrical conductivity were calculated for the alloys from isothermal section of the ternary Al-Ag-Ga system at 200 °C.

X-ray phase contrast tomography by tracking near field speckle

PubMed Central

Wang, Hongchang; Berujon, Sebastien; Herzen, Julia; Atwood, Robert; Laundy, David; Hipp, Alexander; Sawhney, Kawal

2015-01-01

X-ray imaging techniques that capture variations in the x-ray phase can yield higher contrast images with lower x-ray dose than is possible with conventional absorption radiography. However, the extraction of phase information is often more difficult than the extraction of absorption information and requires a more sophisticated experimental arrangement. We here report a method for three-dimensional (3D) X-ray phase contrast computed tomography (CT) which gives quantitative volumetric information on the real part of the refractive index. The method is based on the recently developed X-ray speckle tracking technique in which the displacement of near field speckle is tracked using a digital image correlation algorithm. In addition to differential phase contrast projection images, the method allows the dark-field images to be simultaneously extracted. After reconstruction, compared to conventional absorption CT images, the 3D phase CT images show greatly enhanced contrast. This new imaging method has advantages compared to other X-ray imaging methods in simplicity of experimental arrangement, speed of measurement and relative insensitivity to beam movements. These features make the technique an attractive candidate for material imaging such as in-vivo imaging of biological systems containing soft tissue. PMID:25735237

Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography.

PubMed

Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

2015-01-01

Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography.

Spatiotemporal and spectral characteristics of X-ray radiation emitted by the Z-pinch during the current implosion of quasispherical multiwire arrays

NASA Astrophysics Data System (ADS)

Gritsuk, A. N.

2017-12-01

For the first time, a quasi-spherical current implosion has been experimentally realized on a multimegaampere facility with the peak current of up to 4 MA and a soft X-ray source has been created with high radiation power density on its surface of up to 3 TW/cm2. An increase in the energy density at the centre of the source of soft X-ray radiation (SXR) was experimentally observed upon compression of quasi-spherical arrays with the linear-mass profiling. In this case, the average power density on the surface of the SXR source is three times higher than for implosions of cylindrical arrays of the same mass and close values of the discharge current. Obtained experimental data are compared with the results of modelling the current implosion of multi-wire arrays performed with the help of a three-dimensional radiation-magneto-hydrodynamic code.

Monte Carlo derivation of filtered tungsten anode X-ray spectra for dose computation in digital mammography*

PubMed Central

Paixão, Lucas; Oliveira, Bruno Beraldo; Viloria, Carolina; de Oliveira, Marcio Alves; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

2015-01-01

Objective Derive filtered tungsten X-ray spectra used in digital mammography systems by means of Monte Carlo simulations. Materials and Methods Filtered spectra for rhodium filter were obtained for tube potentials between 26 and 32 kV. The half-value layer (HVL) of simulated filtered spectra were compared with those obtained experimentally with a solid state detector Unfors model 8202031-H Xi R/F & MAM Detector Platinum and 8201023-C Xi Base unit Platinum Plus w mAs in a Hologic Selenia Dimensions system using a direct radiography mode. Results Calculated HVL values showed good agreement as compared with those obtained experimentally. The greatest relative difference between the Monte Carlo calculated HVL values and experimental HVL values was 4%. Conclusion The results show that the filtered tungsten anode X-ray spectra and the EGSnrc Monte Carlo code can be used for mean glandular dose determination in mammography. PMID:26811553

MICROANALYSIS OF MATERIALS USING SYNCHROTRON RADIATION.

DOE Office of Scientific and Technical Information (OSTI.GOV)

JONES,K.W.; FENG,H.

2000-12-01

High intensity synchrotron radiation produces photons with wavelengths that extend from the infrared to hard x rays with energies of hundreds of keV with uniquely high photon intensities that can be used to determine the composition and properties of materials using a variety of techniques. Most of these techniques represent extensions of earlier work performed with ordinary tube-type x-ray sources. The properties of the synchrotron source such as the continuous range of energy, high degree of photon polarization, pulsed beams, and photon flux many orders of magnitude higher than from x-ray tubes have made possible major advances in the possiblemore » chemical applications. We describe here ways that materials analyses can be made using the high intensity beams for measurements with small beam sizes and/or high detection sensitivity. The relevant characteristics of synchrotron x-ray sources are briefly summarized to give an idea of the x-ray parameters to be exploited. The experimental techniques considered include x-ray fluorescence, absorption, and diffraction. Examples of typical experimental apparatus used in these experiments are considered together with descriptions of actual applications.« less

Large gamma-ray detector arrays and electromagnetic separators

NASA Astrophysics Data System (ADS)

Lee, I.-Yang

2013-12-01

The use of large gamma-ray detector arrays with electromagnetic separators is a powerful combination. Various types of gamma-ray detectors have been used; some provide high detector efficiency such as scintillation detector array, others use Ge detectors for good energy resolution, and recently developed Ge energy tracking arrays gives both high peak-to-background ratio and position resolution. Similarly, different types of separators were used to optimize the performance under different experimental requirements and conditions. For example, gas-filled separators were used in heavy element studies for their large efficiency and beam rejection factor. Vacuum separators with good isotope resolution were used in transfer and fragmentation reactions for the study of nuclei far from stability. This paper presents results from recent experiments using gamma-ray detector arrays in combination with electromagnetic separators, and discusses the physics opportunities provided by these instruments. In particular, we review the performance of the instruments currently in use, and discuss the requirements of instruments for future radioactive beam accelerator facilities.

Alpha Particle Induced X-ray Emission in the Classroom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez, Jorge A.; Borunda, Mario F.; Morales, Jaime

2003-08-26

We report on an experimental demonstration in an introductory modern physics course to elucidate the X-ray line spectra, and how they arise from transitions of electrons to inner shells. We seek to determine the effect of limited use of an interactive component as a supplement to a traditional lecture, and how it would improve the student achievement. In this preliminary study the students were exposed to traditional lectures on X-ray production and Bohr's model, they then were given a homework on the abc of X-ray spectra, after which they were given a pre-test on the materials, followed by an in-classmore » demonstration, and a final post-exam. The gain, as measured from pre- to post-exams appears to remark the differences in how students approached the subject before and after the use of the demonstration. This initial study shows the validity of in-class demonstrations as teaching tools and opens a wide new area of research in modern physics teaching.« less

Theoretical and simulation studies of seeding methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pellegrini, Claudio

We report the theoretical and experimental studies done with the support of DOE-Grant DE-SC0009983 to increase an X-ray FEL peak power from the present level of 20 to 40 GW to one or more TW by seeding, undulator tapering and using the new concept of the Double Bunch FEL.

PDB_REDO: automated re-refinement of X-ray structure models in the PDB.

PubMed

Joosten, Robbie P; Salzemann, Jean; Bloch, Vincent; Stockinger, Heinz; Berglund, Ann-Charlott; Blanchet, Christophe; Bongcam-Rudloff, Erik; Combet, Christophe; Da Costa, Ana L; Deleage, Gilbert; Diarena, Matteo; Fabbretti, Roberto; Fettahi, Géraldine; Flegel, Volker; Gisel, Andreas; Kasam, Vinod; Kervinen, Timo; Korpelainen, Eija; Mattila, Kimmo; Pagni, Marco; Reichstadt, Matthieu; Breton, Vincent; Tickle, Ian J; Vriend, Gert

2009-06-01

Structural biology, homology modelling and rational drug design require accurate three-dimensional macromolecular coordinates. However, the coordinates in the Protein Data Bank (PDB) have not all been obtained using the latest experimental and computational methods. In this study a method is presented for automated re-refinement of existing structure models in the PDB. A large-scale benchmark with 16 807 PDB entries showed that they can be improved in terms of fit to the deposited experimental X-ray data as well as in terms of geometric quality. The re-refinement protocol uses TLS models to describe concerted atom movement. The resulting structure models are made available through the PDB_REDO databank (http://www.cmbi.ru.nl/pdb_redo/). Grid computing techniques were used to overcome the computational requirements of this endeavour.

Investigation of neutron interactions with Ge detectors

NASA Astrophysics Data System (ADS)

Baginova, Miloslava; Vojtyla, Pavol; Povinec, Pavel P.

2018-07-01

Interactions of neutrons with a high-purity germanium detector were studied experimentally and by simulations using the GEANT4 tool. Elastic and inelastic scattering of fast neutrons as well as neutron capture on Ge nuclei were observed. Peaks induced by inelastic scattering of neutrons on 70Ge, 72Ge, 73Ge, 74Ge and 76Ge were well visible in the γ-ray spectra. In addition, peaks due to inelastic scattering of neutrons on copper and lead nuclei, including the well-known peak of 208Pb at 2614.51 keV, were detected. The GEANT4 simulations showed that the simulated spectrum was in a good agreement with the experimental one. Differences between the simulated and the measured spectra were due to the high γ-ray intensity of the used neutron source, physics implemented in GEANT4 and contamination of the neutron source.

Stable isotopes and elasmobranchs: tissue types, methods, applications and assumptions.

PubMed

Hussey, N E; MacNeil, M A; Olin, J A; McMeans, B C; Kinney, M J; Chapman, D D; Fisk, A T

2012-04-01

Stable-isotope analysis (SIA) can act as a powerful ecological tracer with which to examine diet, trophic position and movement, as well as more complex questions pertaining to community dynamics and feeding strategies or behaviour among aquatic organisms. With major advances in the understanding of the methodological approaches and assumptions of SIA through dedicated experimental work in the broader literature coupled with the inherent difficulty of studying typically large, highly mobile marine predators, SIA is increasingly being used to investigate the ecology of elasmobranchs (sharks, skates and rays). Here, the current state of SIA in elasmobranchs is reviewed, focusing on available tissues for analysis, methodological issues relating to the effects of lipid extraction and urea, the experimental dynamics of isotopic incorporation, diet-tissue discrimination factors, estimating trophic position, diet and mixing models and individual specialization and niche-width analyses. These areas are discussed in terms of assumptions made when applying SIA to the study of elasmobranch ecology and the requirement that investigators standardize analytical approaches. Recommendations are made for future SIA experimental work that would improve understanding of stable-isotope dynamics and advance their application in the study of sharks, skates and rays. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

Report on the 18th International Conference on X-ray and Inner-Shell Processes (X99).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gemmell, D. S.; Physics

2000-01-01

The 18th conference of the series served as a forum for discussing fundamental issues in the field of x-ray and inner-shell processes and their application in various disciplines of science and technology. Special emphasis was given to the opportunities offered by modern synchrotron x-ray sources. The program included plenary talks, progress reports and poster presentations relating to new developments in the field of x-ray and inner-shell processes. The range of topics included: X-ray interactions with atoms, molecules, clusters, surfaces and solids; Decay processes for inner-shell vacancies; X-ray absorption and emission spectroscopy - Photoionization processes; Phenomena associated with highly charged ionsmore » and collisions with energetic particles; Electron-spin and -momentum spectroscopy; X-ray scattering and spectroscopy in the study of magnetic systems; Applications in materials science, biology, geosciences, and other disciplines; Elastic and inelastic x-ray scattering processes in atoms and molecules; Threshold phenomena (post-collision interaction, resonant Raman processes, etc.); Nuclear absorption and scattering of x-rays; 'Fourth-generation' x-ray sources; Processes exploiting the polarization and coherence properties of x-ray beams; Developments in experimental techniques (x-ray optics, temporal techniques, detectors); Microscopy, spectromicroscopy, and various imaging techniques; Non-linear processes and x-ray lasers; Ionization and excitation induced by charged particles and by x-rays; and Exotic atoms (including 'hollow' atoms and atoms that contain 'exotic' particles).« less

Effect of X-ray exposure on the pharmaceutical quality of drug tablets using X-ray inspection equipment.

PubMed

Uehara, Kazuaki; Tagami, Tatsuaki; Miyazaki, Itaru; Murata, Norikazu; Takahashi, Yoshifumi; Ohkubo, Hiroshi; Ozeki, Tetsuya

2015-06-01

X-ray inspection equipment is widely used to detect missing materials and defective goods in opaque containers. Its application has been expanded to the pharmaceutical industry to detect the presence of drug tablets in aluminum foil press-through packaging. However, the effect of X-rays on the pharmaceutical quality of drug tablets is not well known. In this study, the effect of X-rays on the pharmaceutical quality of drug tablets was investigated. Exposure of acetaminophen, loxoprofen and mefenamic acid tablets to X-ray doses of 0.34 mGy (thrice the dose by X-ray scanning) to 300 Gy (maximum dose from our X-ray equipment) was demonstrated, and the samples were evaluated by formulation tests. Exposure to X-rays did not affect the pharmaceutical quality of the drug content. The samples exposed to X-rays exhibited almost the same profile in formulation tests (dissolution test, disintegrating test and hardness test) as control samples (0 Gy). The combination of X-ray exposure with accelerated temperature and humidity tests (six months) also did not affect the pharmaceutical quality. The color change of light-sensitive drugs (nifedipine and furosemide tablets) after X-ray exposure was negligible (< 1.0). In contrast, tablet color was remarkably changed by light from a D65 lamp. The X-ray scanning and X-ray exposure under our experimental conditions did not affect the pharmaceutical quality of drug tablets.

Design and Fabrication of Soft Morphing Ray Propulsor: Undulator and Oscillator.

PubMed

Kim, Hyung-Soo; Lee, Jang-Yeob; Chu, Won-Shik; Ahn, Sung-Hoon

2017-03-01

A soft morphing ray propulsor capable of generating an undulating motion in its pectoral fins was designed and fabricated. The propulsor used shape memory alloy for actuation, and the body was made with soft polymers. To determine the effects of undulation in the fins, two models that differed in terms of the presence of undulation were fabricated using different polymer materials. The experimental models were tested with a dynamometer to measure and compare thrust tendencies. Thrust measurements were conducted with various fin beat frequencies. Using the experimental data, the concept of an optimized standalone version of the ray robot was suggested and its prototype was fabricated. The fabricated robot was able to swim as fast as 0.26 body length per second and 38% more efficient than other smart material-based ray-like underwater robots.

Dynamic fracture of tantalum under extreme tensile stress.

PubMed

Albertazzi, Bruno; Ozaki, Norimasa; Zhakhovsky, Vasily; Faenov, Anatoly; Habara, Hideaki; Harmand, Marion; Hartley, Nicholas; Ilnitsky, Denis; Inogamov, Nail; Inubushi, Yuichi; Ishikawa, Tetsuya; Katayama, Tetsuo; Koyama, Takahisa; Koenig, Michel; Krygier, Andrew; Matsuoka, Takeshi; Matsuyama, Satoshi; McBride, Emma; Migdal, Kirill Petrovich; Morard, Guillaume; Ohashi, Haruhiko; Okuchi, Takuo; Pikuz, Tatiana; Purevjav, Narangoo; Sakata, Osami; Sano, Yasuhisa; Sato, Tomoko; Sekine, Toshimori; Seto, Yusuke; Takahashi, Kenjiro; Tanaka, Kazuo; Tange, Yoshinori; Togashi, Tadashi; Tono, Kensuke; Umeda, Yuhei; Vinci, Tommaso; Yabashi, Makina; Yabuuchi, Toshinori; Yamauchi, Kazuto; Yumoto, Hirokatsu; Kodama, Ryosuke

2017-06-01

The understanding of fracture phenomena of a material at extremely high strain rates is a key issue for a wide variety of scientific research ranging from applied science and technological developments to fundamental science such as laser-matter interaction and geology. Despite its interest, its study relies on a fine multiscale description, in between the atomic scale and macroscopic processes, so far only achievable by large-scale atomic simulations. Direct ultrafast real-time monitoring of dynamic fracture (spallation) at the atomic lattice scale with picosecond time resolution was beyond the reach of experimental techniques. We show that the coupling between a high-power optical laser pump pulse and a femtosecond x-ray probe pulse generated by an x-ray free electron laser allows detection of the lattice dynamics in a tantalum foil at an ultrahigh strain rate of [Formula: see text] ~2 × 10 8 to 3.5 × 10 8 s -1 . A maximal density drop of 8 to 10%, associated with the onset of spallation at a spall strength of ~17 GPa, was directly measured using x-ray diffraction. The experimental results of density evolution agree well with large-scale atomistic simulations of shock wave propagation and fracture of the sample. Our experimental technique opens a new pathway to the investigation of ultrahigh strain-rate phenomena in materials at the atomic scale, including high-speed crack dynamics and stress-induced solid-solid phase transitions.

Determination of ensemble-average pairwise root mean-square deviation from experimental B-factors.

PubMed

Kuzmanic, Antonija; Zagrovic, Bojan

2010-03-03

Root mean-square deviation (RMSD) after roto-translational least-squares fitting is a measure of global structural similarity of macromolecules used commonly. On the other hand, experimental x-ray B-factors are used frequently to study local structural heterogeneity and dynamics in macromolecules by providing direct information about root mean-square fluctuations (RMSF) that can also be calculated from molecular dynamics simulations. We provide a mathematical derivation showing that, given a set of conservative assumptions, a root mean-square ensemble-average of an all-against-all distribution of pairwise RMSD for a single molecular species, (1/2), is directly related to average B-factors () and (1/2). We show this relationship and explore its limits of validity on a heterogeneous ensemble of structures taken from molecular dynamics simulations of villin headpiece generated using distributed-computing techniques and the Folding@Home cluster. Our results provide a basis for quantifying global structural diversity of macromolecules in crystals directly from x-ray experiments, and we show this on a large set of structures taken from the Protein Data Bank. In particular, we show that the ensemble-average pairwise backbone RMSD for a microscopic ensemble underlying a typical protein x-ray structure is approximately 1.1 A, under the assumption that the principal contribution to experimental B-factors is conformational variability. 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.