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1

High Flux X-ray Beam Intensity Monitor Based upon Rare Gas Scintillation  

SciTech Connect

We have developed a new X-ray beam intensity monitor based upon rare gas scintillation in order to solve (i) the non-ion-saturation problem occurring ionization chambers when irradiated with high flux X-ray beams and (ii) the slow time response of ionization chambers. When argon gas is used, it has been confirmed that the scintillation output was proportional to an X-ray intensity up to 1015 xph/sec, and responded to an X-ray beam with a time resolution better than 50 nsec. The rare gas scintillation X-ray beam monitor developed is compatible to ionization chamber in terms of its readout electronics and the physical size, so that it can easily substitute existing ionization chambers when needed.

Suzuki, Masayo; Toyokawa, Hidenori; Hirota, Katsuya [Japan Synchrotron Radiation Research Institute, SPring-8, Kouto, Mikazuki, Hyogo 679-5198 (Japan)

2004-05-12

2

Compact integrated X-ray intensity and beam position monitor based on rare gas scintillation  

SciTech Connect

We have created and tested a compact integrated X-ray beam intensity and position monitor using Ar-gas scintillation. The light generated inside the device's cavity is detected by diametrically opposed PIN diodes located above and below the beam. The intensity is derived from the sum of the top and bottom signals, while the beam position is calculated from the difference-over-sum of the two signals. The device was tested at Cornell High Energy Synchrotron Source with both 17 keV and 59 keV x-rays. For intensity monitoring, the Ar-scintillation monitor performance is comparable to standard ion chambers in terms of precision. As an X-ray beam position monitor the new device response is linear with vertical beam position over a 2 mm span with a precision of 2 {mu}m.

Revesz, Peter; Ruff, Jacob; Dale, Darren; Krawczyk, Thomas [Cornell University, Cornell High Energy Synchrotron Source, Ithaca, New York 14853 (United States)

2013-05-15

3

A beam intensity monitor for the evaluation beamline for soft x-ray optical elements  

SciTech Connect

Evaluation Beamline for Soft X-Ray Optical Elements (BL-11) at the SR Center of Ritsumeikan University has been operated to measure the wavelength and angular characteristics of soft x-ray optical components in a wavelength range of 0.65-25 nm using a reflecto-diffractometer (RD). The beam intensity monitor that has been equipped in BL-11 has observed the signal of the zero-th order light. For the purpose of more accurate evaluation of the performance of optical components, a new beam intensity monitor to measure the intensity of the first order light from the monochromator in BL-11 has been developed and installed in just front of RD. The strong positive correlation between the signal of the beam monitor and a detector equipped in the RD is shown. It is successful that the beam intensity of the first order light can be monitored in real time.

Imazono, Takashi; Moriya, Naoji; Harada, Yoshihisa; Sano, Kazuo; Koike, Masato [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan); Shimadzu Corp., 1,Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511 (Japan); Shimadzu Emit Co. Ltd., 2-5-23 Kitahama, Chuo-ku, Osaka 541-0041 (Japan)

2012-07-11

4

Thin conductive diamond films as beam intensity monitors for soft x-ray beamlines  

SciTech Connect

Quantitative analysis of X-ray absorption and dichroism data requires knowledge of the beamline photon flux during the measurements. We show that thin conductive (B-doped) diamond thin films can be an alternative to the widely used gold meshes for monitoring the beam intensity of soft X-ray beamlines in situ. Limited by the carbon extended x-ray absorption fine structure oscillations, the diamond films become applicable beginning from about 600 eV photon energy, where the important transition metal edges and the rare-earth edges are found. The 100 nm and 250 nm thick free-standing diamond films were grown and tested against standard gold meshes in real-life dichroism experiments performed at beamline ID08 of the European Synchrotron Radiation Facility, Grenoble, France. Quantitative agreement was found between the two experimental data sets. The films feature an extremely high transmission of about 90% and, at the same time, yield a sufficiently strong and clean reference signal. Furthermore, the thin films do not affect the shape of the transmitted beam. X-rays passing mesh-type monitors are subject to diffraction effects, which widen the beam and become particularly disturbing for small beamsizes in the micrometer range.

Kummer, K.; Fondacaro, A.; Yakhou-Harris, F.; Sessi, V.; Brookes, N. B. [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, B.P. 220, F-38043 Grenoble Cedex (France); Pobedinskas, P.; Janssens, S. D.; Haenen, K. [Hasselt University, Institute for Materials Research (IMO), Wetenschapspark 1, B-3590 Diepenbeek (Belgium); IMEC vzw, IMOMEC, Wetenschapspark 1, B-3590 Diepenbeek (Belgium); Williams, O. A. [Fraunhofer Institut Angewandte Festkoerperphysik, Tullastrasse 72, 79108 Freiburg (Germany); School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Hees, J. [Fraunhofer Institut Angewandte Festkoerperphysik, Tullastrasse 72, 79108 Freiburg (Germany)

2013-03-15

5

Generation of Intense Attosecond X-Ray Pulses Using Ultraviolet Laser Induced Microbunching in Electron Beams  

SciTech Connect

We propose a scheme that combines the echo-enabled harmonic generation technique with the bunch compression and allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser. A few-cycle intense laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Sending this beam through a short undulator results in an intense isolated attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM) can be generated from a 200 nm ultraviolet seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time ({approx}24 attoseconds) and may open a new regime of ultrafast sciences.

Xiang, D.; Huang, Z.; Stupakov, G.; /SLAC

2011-11-29

6

Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li+ ion beam-driven hohlraums  

Microsoft Academic Search

X-ray-producing hohlraums are being studied as indirect drives for inertial confinement fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li+ ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The unfold operator (UFO) code and its suite of auxiliary functions were used extensively in

D. L. Fehl; G. A. Chandler; F. Biggs; R. J. Dukart; A. R. Moats; R. J. Leeper

1997-01-01

7

Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li + ion beam-driven hohlraums  

Microsoft Academic Search

X-ray-producing hohlraums are being studied as indirect drives for inertial confinement fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li{sup +} ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The unfold operator (UFO) code and its suite of auxiliary functions were used extensively

D. L. Fehl; G. A. Chandler; F. Biggs; R. J. Dukart; A. R. Moats; R. J. Leeper

1997-01-01

8

A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam.  

PubMed

Synchrotrons have for decades provided invaluable sources of soft X-rays, the application of which has led to significant progress in many areas of science and technology. But future applications of soft X-rays--in structural biology, for example--anticipate the need for pulses with much shorter duration (femtoseconds) and much higher energy (millijoules) than those delivered by synchrotrons. Soft X-ray free-electron lasers should fulfil these requirements but will be limited in number; the pressure on beamtime is therefore likely to be considerable. Laser-driven soft X-ray sources offer a comparatively inexpensive and widely available alternative, but have encountered practical bottlenecks in the quest for high intensities. Here we establish and characterize a soft X-ray laser chain that shows how these bottlenecks can in principle be overcome. By combining the high optical quality available from high-harmonic laser sources (as a seed beam) with a highly energetic soft X-ray laser plasma amplifier, we produce a tabletop soft X-ray femtosecond laser operating at 10 Hz and exhibiting full saturation, high energy, high coherence and full polarization. This technique should be readily applicable on all existing laser-driven soft X-ray facilities. PMID:15386005

Zeitoun, Ph; Faivre, G; Sebban, S; Mocek, T; Hallou, A; Fajardo, M; Aubert, D; Balcou, Ph; Burgy, F; Douillet, D; Kazamias, S; De Lachèze-Murel, G; Lefrou, T; Le Pape, S; Mercère, P; Merdji, H; Morlens, A S; Rousseau, J P; Valentin, C

2004-09-23

9

Development of ionization chamber for in-line intensity monitoring of large profile parametric X-ray beam  

NASA Astrophysics Data System (ADS)

An in-line ionization chamber has been developed for the real-time measurement of the absolute intensity of the pulsed parametric X-ray (PXR) beam during irradiation experiments. The quasi-monochromatic PXR generating system was developed at the Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. In contrast to typical narrow X-ray beams in synchrotron radiation facilities, the PXR beam profile is as large as approximately 100 mm in diameter with rather uniform flux distribution at the X-ray output port in the experimental hall. The energy of the PXR beam ranges from 5 to 34 keV, which is specified by the PXR target crystal plane and its geometrical condition. The ionization chamber is of a plane parallel type employing 6-?m thick double-sided aluminum vapor-deposited polyester films for the plane electrodes through which the X-ray beam passes. The plane bias electrode has been placed at an equal distance of 25 mm from the two plane earth electrodes that act as the beam windows with an aperture diameter of 120 mm. Due to the pulsed property of the PXR beam and the geometrical configuration of the ionization chamber, the charge-sensitive preamplifier output pulse height represents an integral of the fast electron current, corresponding to a half of the total ionization charge produced by the beam. The intensity of the PXR beam has been measured for various X-ray energies by using nitrogen and argon, respectively, as the filling gas.

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

2013-03-01

10

Modelling properties of hard x-rays generated by the interaction between relativistic electrons and very intense laser beams  

NASA Astrophysics Data System (ADS)

In a previous paper we presented a calculation model for high harmonic generation by relativistic Thomson scattering of the electromagnetic radiation by free electrons. In this paper we present a similar model for the calculation of the energies of hard x-rays (20- 200 keV) resulted from the interaction between relativistic electrons (20-100 MeV) and very intense laser beams. Starting from the relativistic equations of motion of an electron in the electromagnetic field we show that the Liènard-Wiechert equation leads to electromagnetic waves whose frequencies are in the domain of hard x-rays. When the relativistic parameter of the laser beam is greater than unity, the model predicts the existence of harmonics of the above frequencies. Our theoretical values are in good agreement with experimental values of the x-ray energies from the literature and predict accurately their angular distribution.

Popa, Alexandru

2009-01-01

11

Review on Recent High Intensity Physics Experiments Relevant to X-Ray and Quantum Beam Generation at JAEA  

NASA Astrophysics Data System (ADS)

The authors describe firstly the lasers for high intensity physics experiments at JAEA including J-KAREN and JLITE-X lasers which can deliver 00TW and 0TW laser power, respectively. Secondly the authors describe demonstration of flying mirror technique which will become a new technique to make a coherent tunable x-ray source. Thirdly a femto-second laser driven incoherent soft x-ray source and its imaging applications for nano-structures are described. The th topic includes femto-second laser driven multiple quantum beam generation and its applications using a laser driven thin foil target.

Daido, H.; Pirozhkov, A.; Nishiuchi, M.; Yogo, A.; Orimo, S.; Ogura, K.; Sagisaka, A.; Daito, I.; Mori, M.; Ikegami, M.; Kiriyama, H.; Okada, H.; Bulanov, S.; Esirkepov, T.; Kanazawa, S.; Kondo, S.; Shimomura, T.; Tanoue, M.; Nakai, Y.; Sasao, H.; Wakai, D.; Bolton, P.; Fukuda, Y.; Faenov, A.; Pikuz, T.; Suzuki, M.; Tampo, M.; Sakaki, H.; Tajima, T.; Kawanishi, S.; Kawachi, T.; Nishikino, M.; Choi, I. W.; Kim, C. M.; Jeong, T. M.; Hafz, N.; Yu, T. J.; Sung, J. H.; Noh, Y.-C.; Ko, D.-K.; Lee, J.; Oishi, Y.; Nemoto, K.; Nayuki, T.; Fujii, T.; Nagatomo, H.; Nagai, K.; Nishimura, H.

12

Quantitative Measurements of X-ray Intensity  

SciTech Connect

This chapter describes the characterization of several X-ray sources and their use in calibrating different types of X-ray cameras at National Security Technologies, LLC (NSTec). The cameras are employed in experimental plasma studies at Lawrence Livermore National Laboratory (LLNL), including the National Ignition Facility (NIF). The sources provide X-rays in the energy range from several hundred eV to 110 keV. The key to this effort is measuring the X-ray beam intensity accurately and traceable to international standards. This is accomplished using photodiodes of several types that are calibrated using radioactive sources and a synchrotron source using methods and materials that are traceable to the U.S. National Institute of Standards and Technology (NIST). The accreditation procedures are described. The chapter begins with an introduction to the fundamental concepts of X-ray physics. The types of X-ray sources that are used for device calibration are described. The next section describes the photodiode types that are used for measuring X-ray intensity: power measuring photodiodes, energy dispersive photodiodes, and cameras comprising photodiodes as pixel elements. Following their description, the methods used to calibrate the primary detectors, the power measuring photodiodes and the energy dispersive photodiodes, as well as the method used to get traceability to international standards are described. The X-ray source beams can then be measured using the primary detectors. The final section then describes the use of the calibrated X-ray beams to calibrate X-ray cameras. Many of the references are web sites that provide databases, explanations of the data and how it was generated, and data calculations for specific cases. Several general reference books related to the major topics are included. Papers expanding some subjects are cited.

Haugh, M. J., Schneider, M.

2011-09-01

13

Simulation of X-ray beam collimation by polycapillaries  

NASA Astrophysics Data System (ADS)

Simulation of X-ray propagation in polycapillaries (X-ray lens) was processed with the Ray-Tracing program SHADOW. The X-ray intensity distribution was investigated on cylindrical lens and parallel-beam lens. These polycapillary X-ray optics demonstrate good collimation capability with a point X-ray source.

Liu, Andong

2005-07-01

14

Simulation of X-ray beam collimation by polycapillaries  

Microsoft Academic Search

Simulation of X-ray propagation in polycapillaries (X-ray lens) was processed with the Ray-Tracing program SHADOW. The X-ray intensity distribution was investigated on cylindrical lens and parallel-beam lens. These polycapillary X-ray optics demonstrate good collimation capability with a point X-ray source.

Andong Liu

2005-01-01

15

Development of confocal micro X-ray fluorescence instrument using two X-ray beams  

NASA Astrophysics Data System (ADS)

A new confocal micro X-ray fluorescence instrument was developed. This instrument has two independent micro X-ray tubes with Mo targets. A full polycapillary X-ray lens was attached to each X-ray tube. Another half polycapillary lens was attached to a silicon drift X-ray detector (SDD). The focal spots of the three lenses were adjusted to a common position. The effects of the excitation of two X-ray beams were investigated. The instrument enabled highly sensitive three-dimensional X-ray fluorescence analysis. We confirmed that the X-ray fluorescence intensity from the sample increased by applying the two independent X-ray tubes in confocal configuration. Elemental depth profiling of black wheat was demonstrated with the result that each element in the surface coat of a wheat grain showed unique distribution.

Tsuji, Kouichi; Nakano, Kazuhiko; Ding, Xunliang

2007-07-01

16

Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li{sup +} ion beam-driven hohlraums  

Microsoft Academic Search

X-ray-producing hohlraums are being studied as indirect drives for Inertial Confinement Fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li{sup +} ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The UFO unfold code and its suite of auxiliary functions were used extensively in

D. L. Fehl; G. A. Chandler; F. Biggs; R. J. Dukart; A. R. Moats; R. J. Leeper

1996-01-01

17

Electron beam parallel X-ray generator  

NASA Technical Reports Server (NTRS)

Broad X ray source produces a highly collimated beam of low energy X rays - a beam with 2 to 5 arc minutes of divergence at energies between 1 and 6 keV in less than 5 feet. The X ray beam is generated by electron bombardment of a target from a large area electron gun.

Payne, P.

1967-01-01

18

Evaluation of femtosecond X-rays produced by Thomson scattering under linear and nonlinear interactions between a low-emittance electron beam and an intense polarized laser light  

Microsoft Academic Search

The mechanisms of Thomson scattering under linear and nonlinear interactions are discussed theoretically and used to evaluate characters of femtosecond (fs) X-rays produced by collision between a low-emittance electron beam and an intense polarized laser light. In the evaluation, we start from the differential cross section of the Thomson scattering under the linear interaction, and calculate the effects of the

J. Yang; M. Washio; A. Endo; T. Hori

1999-01-01

19

High speed x-ray beam chopper  

DOEpatents

A fast, economical, and compact x-ray beam chopper with a small mass and a small moment of inertia whose rotation can be synchronized and phase locked to an electronic signal from an x-ray source and be monitored by a light beam is disclosed. X-ray bursts shorter than 2.5 microseconds have been produced with a jitter time of less than 3 ns.

McPherson, Armon (Oswego, IL); Mills, Dennis M. (Naperville, IL)

2002-01-01

20

Relativistic self-focusing of ultra-high intensity X-ray laser beams in warm quantum plasma with upward density profile  

NASA Astrophysics Data System (ADS)

The results of a numerical study of high-intensity X-ray laser beam interaction with warm quantum plasma (WQP) are presented. By means of an upward ramp density profile combined with quantum factors specially the Fermi velocity, we have demonstrated significant relativistic self-focusing (RSF) of a Gaussian electromagnetic beam in the WQP where the Fermi temperature term in the dielectric function is important. For this purpose, we have considered the quantum hydrodynamics model that modifies refractive index of inhomogeneous WQPs with the inclusion of quantum correction through the quantum statistical and diffraction effects in the relativistic regime. Also, to better illustration of the physical difference between warm and cold quantum plasmas and their effect on the RSF, we have derived the envelope equation governing the spot size of X-ray laser beam in Q-plasmas. In addition to the upward ramp density profile, we have found that the quantum effects would be caused much higher oscillation and better focusing of X-ray laser beam in the WQP compared to that of cold quantum case. Our computational results reveal the importance of the use of electrons density profile and Fermi speed in enhancing self-focusing of laser beam.

Habibi, M.; Ghamari, F.

2014-05-01

21

Diamond X-ray Beam Position Monitors  

SciTech Connect

Modern Synchrotrons are capable of significant per-pulse x-ray flux, and time resolved pulse-probe experiments have become feasible. These experiments provide unique demands on x-ray monitors, as the beam position, flux and arrival time all potentially need to be recorded for each x-ray pulse. Further, monitoring of white x-ray beam position and flux upstream of beamline optics is desirable as a diagnostic of the electron source and insertion device alignment. We report on diamond quadrant monitors which provide beam diagnostics for a variety of applications, for both white and monochromatic beams. These devices have a position resolution of 25 nm for a stable beam, are linear in flux over at least 11 orders of magnitude, and can resolve beam motion shot-by-shot at repetition rates up to 6.5 MHz.

Smedley J.; Keister J.; Heroux, A.; Gaowei, M.; Muller, E.; Bohon, J.; Attenkofer, K.; Distel, J.

2011-09-01

22

Dependence of relative intensity of L 1 sub-shell X-rays on ion beam energy  

NASA Astrophysics Data System (ADS)

In a previous work, it was shown that L shell X-ray yields relative to the L ? transition depend on the irradiation ion beam energy and the chemical species being irradiated [M.A. Reis, P.C. Chaves, J.C. Soares, Nucl. Instr. and Meth. B 239 (2005) 413]. Further studies give rise to the possibility that this dependence persists for transitions to the same sub-shell, where the ionization process is expected to play no role [P.C. Chaves, M.A. Reis, in: Miloš Budnar, Matjaž Kav?i? (Eds.), Proceedings (CD) of the Tenth International Conference on Particle Induced X-ray Emission and its Analytical Application, 4-8 June, Portorož - Slovenia, J. Stefan Institute, Ljubljana, 2004, p. 810]. In the present work, very high counting statistics (>4 × 10 6 counts in the peak) W-L spectra collected using a Si(Li) detector and Mo-L spectra obtained using the high resolution Johanson type crystal spectrometer from the Josef Stefan Institute were studied. In the case of Mo, an ultra pure Mo metal foil was used to avoid any possible target contamination and spectra were obtained for proton beam energies between 0.4 and 2.0 MeV. In the case of the W spectra, proton beam energies between 1.40 and 2.38 MeV were used. Normalizing to the theoretical yield ratios and plotting results as a function of the reduced velocity allows a single curve to be drawn for both cases. In this communication the results obtained are presented and discussed.

Chaves, P. C.; Reis, M. A.; Barradas, N. P.; Kav?i?, Matjaž

2007-08-01

23

Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li{sup +} ion beam-driven hohlraums  

SciTech Connect

X-ray-producing hohlraums are being studied as indirect drives for Inertial Confinement Fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li{sup +} ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The UFO unfold code and its suite of auxiliary functions were used extensively in obtaining time- resolved x-ray spectra and radiation temperatures from this diagnostic. UFO was also used to obtain fitted response functions from calibration data, to simulate data from blackbody x-ray spectra of interest, to determine the suitability of various unfolding parameters (e.g., energy domain, energy partition, smoothing conditions, and basis functions), to interpolate the XRD signal traces, and to unfold experimental data. The simulation capabilities of the code were useful in understanding an anomalous feature in the unfolded spectra at low photon energies ({le} 100 eV). Uncertainties in the differential and energy-integrated unfolded spectra were estimated from uncertainties in the data. The time-history of the radiation temperature agreed well with independent calculations of the wall temperature in the hohlraum.

Fehl, D.L.; Chandler, G.A.; Biggs, F.; Dukart, R.J.; Moats, A.R.; Leeper, R.J.

1996-07-01

24

Time-dependent, x-ray spectral unfolds and brightness temperatures for intense Li{sup +} ion beam-driven hohlraums  

SciTech Connect

X-ray-producing hohlraums are being studied as indirect drives for inertial confinement fusion targets. In a 1994 target series on the PBFAII accelerator, cylindrical hohlraum targets were heated by an intense Li{sup +} ion beam and viewed by an array of 13 time-resolved, filtered x-ray detectors (XRDs). The unfold operator (UFO) code and its suite of auxiliary functions were used extensively in obtaining time-resolved x-ray spectra and radiation temperatures from this diagnostic. The UFO was also used to obtain fitted response functions from calibration data, to simulate data from blackbody x-ray spectra of interest, to determine the suitability of various unfolding parameters (e.g., energy domain, energy partition, smoothing conditions, and basis functions), to interpolate the XRD signal traces, and to unfold experimental data. The simulation capabilities of the code were useful in understanding an anomalous feature in the unfolded spectra at low photon energies ({le}100 eV). Uncertainties in the differential and energy-integrated unfolded spectra were estimated from uncertainties in the data. The time{endash}history of the radiation temperature agreed well with independent calculations of the wall temperature in the hohlraum. {copyright} {ital 1997 American Institute of Physics.}

Fehl, D.L.; Chandler, G.A.; Biggs, F.; Dukart, R.J.; Moats, A.R.; Leeper, R.J. [Sandia National Laboratories Albuquerque, New Mexico 87185 (United States)] [Sandia National Laboratories Albuquerque, New Mexico 87185 (United States)

1997-01-01

25

A new beamstop for microfocus X-ray capillary beams  

PubMed Central

In order to accurately measure the photon flux and to assist in aligning the beam, we have designed a modified beam stop device based on a photo diode integrated with the beam stop. The beam stop contains a small CdWO4 crystal that completely stops the X-rays and at the same time produces photoluminescence proportional to the X-ray flux. The light is then guided to a photosensitive diode, using a flexible light pipe, to monitor the flux. With this device we achieve the goal of stopping the primary X-ray beam and simultaneously monitoring the X-ray intensity, thus eliminating the need for integrating ion-chambers into the capillary or collimator mount.

Englich, Ulrich; Revesz, Peter; Miller, William

2011-01-01

26

A new beamstop for microfocus X-ray capillary beams.  

PubMed

In order to accurately measure the photon flux and to assist in aligning the beam, we have designed a modified beam stop device based on a photo diode integrated with the beam stop. The beam stop contains a small CdWO(4) crystal that completely stops the X-rays and at the same time produces photoluminescence proportional to the X-ray flux. The light is then guided to a photosensitive diode, using a flexible light pipe, to monitor the flux. With this device we achieve the goal of stopping the primary X-ray beam and simultaneously monitoring the X-ray intensity, thus eliminating the need for integrating ion-chambers into the capillary or collimator mount. PMID:21822345

Englich, Ulrich; Revesz, Peter; Miller, William

2011-09-01

27

A high-intensity highly coherent soft X-ray femtosecond laser seeded by a high harmonic beam  

Microsoft Academic Search

Synchrotrons have for decades provided invaluable sources of soft X-rays, the application of which has led to significant progress in many areas of science and technology. But future applications of soft X-rays-in structural biology, for example-anticipate the need for pulses with much shorter duration (femtoseconds) and much higher energy (millijoules) than those delivered by synchrotrons. Soft X-ray free-electron lasers should

Ph. Zeitoun; G. Faivre; S. Sebban; T. Mocek; A. Hallou; M. Fajardo; D. Aubert; Ph. Balcou; F. Burgy; D. Douillet; S. Kazamias; G. de Lachèze-Murel; T. Lefrou; S. le Pape; P. Mercère; H. Merdji; A. S. Morlens; J. P. Rousseau; C. Valentin

2004-01-01

28

Exotic X-ray Sources from Intermediate Energy Electron Beams  

NASA Astrophysics Data System (ADS)

High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, ``novel'' x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic ``structure'' of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR).

Chouffani, K.; Wells, D.; Harmon, F.; Jones, J. L.; Lancaster, G.

2003-08-01

29

Exotic X-ray Sources from Intermediate Energy Electron Beams  

SciTech Connect

High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, 'novel' x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic 'structure' of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR)

Chouffani, K.; Wells, D.; Harmon, F. [Idaho Accelerator Center, Idaho State University, Pocatello, ID 83209 (United States); Jones, J.L.; Lancaster, G. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID 83415-280 (United States)

2003-08-26

30

Bunch by Bunch X-Ray Beam Position and Intensity Monitoring Using a Single Crystal Diamond Detector  

NASA Astrophysics Data System (ADS)

Diamond is an outstanding material for the production of semitransparent in situ photon beam monitors which can withstand the high dose rates occurring in new generation synchrotron radiation storage rings and in free electron lasers. Here we report on the development of a 500 ?m thick freestanding, single-crystal chemical vapor deposited diamond detector with segmented electrodes; it exhibits a high resistivity of some 1015 cm which allows charge integration operations. Using the latter at a frame rate of 8.33 kHz in combination with a needle synchrotron radiation beam and mesh scans, the inhomogeneity of the sensor was found to be of the order of 2%. With a measured electronics noise of 2 pA / Hz1/2 a 0.05% relative precision in the intensity measurements (at 1 ?A) and a 0.1 ?m resolution in the position encoding have been estimated. Moreover, the high electron-hole mobility of diamond compared with other active materials enables very fast charge collection. This allowed us to utilize single pulse integration to simultaneously detect the intensity and the position of each synchrotron radiation photon bunch generated by a bending magnet.

Antonelli, M.; Tallaire, A.; Achard, J.; Carrato, S.; Cautero, G.; de Sio, A.; di Fraia, M.; Giuressi, D.; Menk, R. H.; Pace, E.

2012-08-01

31

Diffraction optical elements with deep phase profile obtained with the use of x-ray parallel intensive beam  

NASA Astrophysics Data System (ADS)

X-ray lithography with synchrotron radiation was applied for formation of the Fresnel zone structure profile onto a curved surface of a refractive polymer lens to achieve multifocus properties of the lens. First prototypes of the hybrid refractive-diffractive lens were fabricated in such a way and their optical properties were investigated. Some possibilities for creation of diffraction apochromatic optical elements are considered as well.

Koronkevich, Voldemar P.; Kulipanov, G. N.; Makarov, Oleg A.; Nazmov, V. P.; Pindyurin, Valery F.; Sinyukov, M. P.

1995-11-01

32

X-ray beam induced current method at the laboratory x-ray source  

SciTech Connect

The x-ray beam induced current method (XBIC) is realized on the laboratory x-ray source using the polycapillary x-ray optics. It is shown that rather good images of grain boundaries in Si can be obtained by this method. The parameters of x-ray beam are estimated by the simulation of Schottky diode image. A good correlation between the experimental and calculated grain boundary XBIC contrast is obtained. The possibilities of laboratory source based XBIC method are estimated.

Fahrtdinov, R. R.; Feklisova, O. V.; Grigoriev, M. V.; Irzhak, D. V.; Roshchupkin, D. V.; Yakimov, E. B. [Institution of Russian Academy of Sciences, Institute of Microelectronics Technology, and High-Purity Materials RAS, Chernogolovka 142432 (Russian Federation)

2011-09-15

33

X-ray beam induced current method at the laboratory x-ray source  

NASA Astrophysics Data System (ADS)

The x-ray beam induced current method (XBIC) is realized on the laboratory x-ray source using the polycapillary x-ray optics. It is shown that rather good images of grain boundaries in Si can be obtained by this method. The parameters of x-ray beam are estimated by the simulation of Schottky diode image. A good correlation between the experimental and calculated grain boundary XBIC contrast is obtained. The possibilities of laboratory source based XBIC method are estimated.

Fahrtdinov, R. R.; Feklisova, O. V.; Grigoriev, M. V.; Irzhak, D. V.; Roshchupkin, D. V.; Yakimov, E. B.

2011-09-01

34

Coherent X-ray Cherenkov radiation produced by microbunched beams  

NASA Astrophysics Data System (ADS)

Analytical and numerical results on the coherent X-ray Cherenkov radiation (CXCR) produced by microbunched beams in the region near the K-, L-edges of materials are obtained. The results show that CXCR can serve as a suitable mechanism for production intense beams of photons in the "water window" region as well as for studying the important microbunching process at FLASH TESLA, LCLS and other FELs.

Aginian, M. A.; Ispirian, K. A.; Ispiryan, M. K.; Ivanyan, M. I.

2014-05-01

35

Calibrating X-ray Imaging Devices for Accurate Intensity Measurement  

SciTech Connect

The purpose of the project presented is to develop methods to accurately calibrate X-ray imaging devices. The approach was to develop X-ray source systems suitable for this endeavor and to develop methods to calibrate solid state detectors to measure source intensity. NSTec X-ray sources used for the absolute calibration of cameras are described, as well as the method of calibrating the source by calibrating the detectors. The work resulted in calibration measurements for several types of X-ray cameras. X-ray camera calibration measured efficiency and efficiency variation over the CCD. Camera types calibrated include: CCD, CID, back thinned (back illuminated), front illuminated.

Haugh, M. J.

2011-07-28

36

X-ray beam induced current method at the laboratory x-ray source.  

PubMed

The x-ray beam induced current method (XBIC) is realized on the laboratory x-ray source using the polycapillary x-ray optics. It is shown that rather good images of grain boundaries in Si can be obtained by this method. The parameters of x-ray beam are estimated by the simulation of Schottky diode image. A good correlation between the experimental and calculated grain boundary XBIC contrast is obtained. The possibilities of laboratory source based XBIC method are estimated. PMID:21974589

Fahrtdinov, R R; Feklisova, O V; Grigoriev, M V; Irzhak, D V; Roshchupkin, D V; Yakimov, E B

2011-09-01

37

Highly intense monochromatic X-ray diffraction facility for high-pressure research at SPring8  

Microsoft Academic Search

Beamline BL10XU at SPring-8, designed for X-ray diffraction experiments using diamond anvil cells at high pressure and low\\/high temperature, is continuously upgraded. The X-ray source, optics, and attractive experimental equipment such as simultaneous measurement systems have been optimized over the past years. The high energy and high intensity monochromatic X-ray beams emitted by an undulator source, focused using a characteristic

Yasuo Ohishi; Naohisa Hirao; Nagayoshi Sata; Kei Hirose; Masaki Takata

2008-01-01

38

Standoff detection of hidden objects using backscattered ultra-intense laser-produced x-rays  

SciTech Connect

Ultra-intense laser-produced sub-ps X-ray pulses can detect backscattered signals from objects hidden in aluminium containers. Coincident measurements using primary X-rays enable differentiation among acrylic, copper, and lead blocks inside the container. Backscattering reveals the shapes of the objects, while their material composition can be identified from the modification methods of the energy spectra of backscattered X-ray beams. This achievement is an important step toward more effective homeland security.

Kuwabara, H. [IHI Corporation, 1, Shin-Nakahara-cho, Isogo-ku, Yokohama 235-8501 (Japan)] [IHI Corporation, 1, Shin-Nakahara-cho, Isogo-ku, Yokohama 235-8501 (Japan); Mori, Y.; Kitagawa, Y. [The Graduate School for the Creation of New Photonics Industries, 1955-1 Kurematsucho, Nishiku, Hamamatsu, Shizuoka 431-1202 (Japan)] [The Graduate School for the Creation of New Photonics Industries, 1955-1 Kurematsucho, Nishiku, Hamamatsu, Shizuoka 431-1202 (Japan)

2013-08-28

39

Standoff detection of hidden objects using backscattered ultra-intense laser-produced x-rays  

NASA Astrophysics Data System (ADS)

Ultra-intense laser-produced sub-ps X-ray pulses can detect backscattered signals from objects hidden in aluminium containers. Coincident measurements using primary X-rays enable differentiation among acrylic, copper, and lead blocks inside the container. Backscattering reveals the shapes of the objects, while their material composition can be identified from the modification methods of the energy spectra of backscattered X-ray beams. This achievement is an important step toward more effective homeland security.

Kuwabara, H.; Mori, Y.; Kitagawa, Y.

2013-08-01

40

Effects of intense x-ray radiation on polycapillary fiber performance  

Microsoft Academic Search

Several applications of Kumakhov polycapillary optics require extended exposure to intense x- ray radiation. No degradation of performance has been observed when using polycapillary x- ray optics with laboratory sources. As part of an ongoing study to develop an understanding of damage mechanisms and performance limitations, borosilicate glass polycapillaries have been exposed to white beam bending magnet synchrotron radiation with

Bimal K. Rath; D. C. Aloisi; Donald H. Bilderback; N. Gao; Walter M. Gibson; F. A. Hofmann; B. E. Homan; Chris J. Jezewski; I. L. Klotzko; J. M. Mitchell; S. M. Owens; Johannes B. Ullrich; Lei Wang; Gregory M. Wells; Qi Fan Xiao; Carolyn A. MacDonald

1995-01-01

41

An increase of utilization efficiency of X-ray beam  

NASA Astrophysics Data System (ADS)

The features of absorbed dose field formation in objects irradiated with scanned X-ray beams at double—and four-sided irradiation were investigated both analytically and by Monte Carlo methods. An analytical approach uses an angular/spectrum X-ray characteristics calculated with PENELOPE, JEANT 4 and ModeXR codes. It was shown that the special angular orientation of electron beam incidence on the X-ray converter leads to X-ray dose smoothing on the surface of the irradiated object. At the same time, a double-sided irradiation can provide high X-ray beam efficiency at dose uniformity ration (DUR) <1.5 for sizeable object thickness. At four-sided irradiation, the angular orientation of electron beam incidence on the X-ray converter should be changed so as to focus the electrons to the center of the converter. At this mode X-ray beam efficiency is more than 60%.

Lazurik, V. T.; Pismenesky, S. A.; Popov, G. F.; Rudychev, D. V.; Rudychev, V. G.

2007-11-01

42

1D X-ray Beam Compressing Monochromators  

SciTech Connect

A total beam compression of 5 and 10 corresponding to the asymmetry angles of 9 deg. and 12 deg. is achieved with V-5 and V-10 monochromators, respectively, in standard single crystal pure germanium (220) X-ray beam compressing (V-shaped) monochromators for CuKalpha{sub 1} radiation. A higher 1D compression of X-ray beam is possible using larger angles of asymmetry, however it is achieved at the expense of the total intensity, which is decreased due to the refraction effect. To increase the monochromator intensity, several ways are considered both theoretically and experimentally. Linearly graded germanium rich Ge{sub x}Si{sub (1-x)} single crystal was used to prepare a V-21 single crystal monochromator with 15 deg. asymmetry angles (compression factor of 21). Its temperature gradient version is discussed for CuKalpha{sub 1} radiation. X-ray diffraction measurements on the graded GeSi monochromator showed more than 3-times higher intensity at the output compared with that of a pure Ge monochromator.

Korytar, D.; Dobrocka, E.; Konopka, P.; Zaprazny, Z. [Institute of Electrical Engineering, SAS, Vrbovska cesta 110, SK 92101 Piest'any (Slovakia); Ferrari, C. [CNR IMEM Institute, Parma (Italy); Mikulik, P. [Masaryk University, Brno (Czech Republic); Vagovic, P. [ISS FZK Karlsruhe (Germany); Ac, V. [TnUAD Trencin (Slovakia); Erko, A. [Bessy Berlin (Germany); Abrosimov, N. [IKZ Berlin (Germany)

2010-04-06

43

Small GOES flares with intense hard X-ray emission  

NASA Astrophysics Data System (ADS)

Large solar flares with intense soft X-ray emission (i.e., high GOES class) generally tend to show a strong hard X-ray emission. However, there are examples of low GOES class events with unusually strong hard X-ray emission. In this paper, we analyse the morphology and physical parameters of such small GOES intensity flares with strong hard X-ray emission, using Yohkoh SXT images and photometric data obtained from INTERBALL-TAIL RF15-I X-ray Photometer. We observe a great variety in the soft X-ray morphology of such flares (a large diversity of loop configurations). Some of these flares do not differ greatly in their morphology from large intense flares, but most flares are generally compact. In spite of their low intensities in soft X-rays, the significant hard X-ray emission is observed by INTERBALL up to 30 60 keV. We briefly discuss some of the possible causes of the soft and hard X-ray emission ratio of these events.

Siarkowski, M.; Falewicz, R.; Berlicki, A.

2006-01-01

44

Intense X-ray machine for penetrating radiography  

NASA Astrophysics Data System (ADS)

Penetrating radiography has been used for many years in the nuclear weapons research programs. Infrequently penetrating radiography has been used in conventional weapons research programs. For example the Los Alamos PHERMEX machine was used to view uranium rods penetrating steel for the GAU-8 program, and the Ector machine was used to see low density regions in forming metal jets. The armor/anti-armor program at Los Alamos has created a need for an intense flash X-ray machine that can be dedicated to conventional weapons research. The Balanced Technology Initiative, through DARPA, has funded the design and construction of such a machine at Los Alamos. It will be an 8- to 10-MeV diode machine capable of delivering a dose of 500 R at 1 m with a spot size of less than 5 mm. The machine used an 87.5-stage low inductance Marx generator that charges up a 7.4-(Omega), 32-ns water line. The water line is discharged through a self-breakdown oil switch into a 12.4-(Omega) water line that rings up the voltage into the high impendance X-ray diode. A long (233-cm) vacuum drift tube is used to separate the large diameter oil-insulated diode region from the X-ray source area that may be exposed to high overpressures by the explosive experiments. The electron beam is selffocused at the target area using a low pressure background gas.

Lucht, Roy A.; Eckhouse, Shimon

45

Generation of the Submicron Soft X-Ray Beam Using a Fresnel Zone Plate  

NASA Astrophysics Data System (ADS)

We have developed a fully coherent x-ray laser at 13.9 nm and the application research has been started. The generation of submicron x-ray beam is important for the application of high intensity x-ray beam, such as the non-linear optics, the material science, and the biology. The submicron x-ray bee am is generated by the soft x-ray laser with using a Fresnel zone plate. The spot diameter is estimated about 680 nm (290 nm at FWHM) by the theoretical calculation. In this experiment, the diameter of the x-ray beam is measured by the knife-edge scan. The diameter and the intensity are estimated 730 nm (310 nm at FWHM) and 3x1011 W/cm2, respectively.

Nishikino, M.; Kawazome, H.; Tanaka, M.; Kishimoto, M.; Hasegawa, N.; Ochi, Y.; Kawachi, T.; Sukegawa, K.; Yamatani, H.; Nagashima, K.; Kato, Y.

46

Beam synchronous detection techniques for X-Ray spectroscopy  

NASA Astrophysics Data System (ADS)

The Photo diode detectors combine a set of properties that make them most appropriate, in particular, for X-ray Magnetic Circular Dichroism (XMCD) experiments. Under standard operating conditions, the detection bandwidth is primarily limited by the transimpedance preamplifier that converts the very low ac photocurrent into a voltage. On the other hand, when the photodiode is reverse biased, its finite shunt resistance will cause an undesirable, temperature dependent DC dark current. The best strategy to get rid of it is to use synchronous detection techniques. A classical implementation is based on the use of a chopper modulating the X-ray beam intensity at rather low frequencies (typically below 1 kHz). Here we report on the recent development of a fast Xray detection which has the capability to fully exploit the frequency structure of the ESRF X-ray beam (355 KHz and its harmonics). The availability of new wide band preamplifiers allowed us to extend the working frequency range up to a few MHz. A beam synchronous data processing was implemented in large FPGAs. Performances of the new detection system implemented at the ESRF beamline ID12 are illustrated with detection of the Fe K-edge XMCD spectra in garnets, using 4 bunches operation mode with modulation frequency of 1.4 MHz.

Goujon, Gérard; Rogalev, Andreï; Goulon, José; Feite, Serge; Wilhelm, Fabrice

2013-03-01

47

Generation of intense ultrashort x-ray pulses  

SciTech Connect

Modeling of x-ray emission from targets heated by an ultrashort-pulse high-intensity optical laser is discussed. One application, using the emitted x rays, is pumping inner-shell photo-ionized x-ray lasers. Short wavelength lasing ({lambda} {le} 15 {Angstrom}) requires fast rise-time 1--3 key x rays to ionize inner K-shell electrons. It has been shown that structured targets, consisting of grooves on a solid material or a composite of clusters, have high absorption. We model grooved targets as an ensemble of exploding foils finding that the rise time of x rays is rapid enough for pumping inner-shell x-ray lasers. We show that simple atomic models can overestimate the energy in x-ray emission bands. High-Z materials are found to have the highest conversion efficiency but mid-Z materials can be used to provide a band of emission at a particular energy. We show that the pondermotive inhibition of expansion has only a small effect on the x-ray emission. The emission of a Au plasma is found to be appropriate for pumping inner-shell lasing at 14.6 {Angstrom} in Ne. The required optical laser intensity is of order 10{sup 17} W/cm{sup 2} using a 100 fsec FWHM duration pulse. To produce a laser with a gain-length product of order 10 requires 5--15 J of optical energy.

Eder, D.C.; London, R.A.; Rosen, M.D. [Lawrence Livermore National Lab., CA (United States); Strobel, G.L. [Georgia Univ., Macon, GA (United States)

1993-08-01

48

Thermal deformation of cryogenically cooled silicon crystals under intense X-ray beams: measurement and finite-element predictions of the surface shape  

PubMed Central

X-ray crystal monochromators exposed to white-beam X-rays in third-generation synchrotron light sources are subject to thermal deformations that must be minimized using an adequate cooling system. A new approach was used to measure the crystal shape profile and slope of several cryogenically cooled (liquid nitrogen) silicon monochromators as a function of beam power in situ and under heat load. The method utilizes multiple angular scans across the Bragg peak (rocking curve) at various vertical positions of a narrow-gap slit downstream from the monochromator. When increasing the beam power, the surface of the liquid-nitrogen-cooled silicon crystal deforms from a concave shape at low heat load to a convex shape at high heat load, passing through an approximately flat shape at intermediate heat load. Finite-element analysis is used to calculate the crystal thermal deformations. The simulated crystal profiles and slopes are in excellent agreement with experiments. The parameters used in simulations, such as material properties, absorbed power distribution on the crystal and cooling boundary conditions, are described in detail as they are fundamental for obtaining accurate results.

Zhang, Lin; Sanchez del Rio, Manuel; Monaco, Giulio; Detlefs, Carsten; Roth, Thomas; Chumakov, Aleksandr I.; Glatzel, Pieter

2013-01-01

49

Resonant Auger Effect at High X-Ray Intensity  

SciTech Connect

The resonant Auger effect of atomic neon exposed to high-intensity x-ray radiation in resonance with the 1s {yields} 3p transition is discussed. High intensity here means that the x-ray peak intensity is sufficient ({approx} 10{sup 18} W/cm{sup 2}) to induce Rabi oscillations between the neon ground state and the 1s{sup -1}3p ({sup 1}P) state within the relaxation lifetime of the inner-shell vacancy. For the numerical analysis presented, an effective two-level model, including a description of the resonant Auger decay process, is employed. Both coherent and chaotic x-ray pulses are treated. The latter are used to simulate radiation from x-ray free-electron lasers based on the principle of self-amplified spontaneous emission. Observing x-ray-driven atomic population dynamics in the time domain is challenging for chaotic pulse ensembles. A more practical option for experiments using x-ray free-electron lasers is to measure the line profiles in the kinetic energy distribution of the resonant Auger electron. This provides information on both atomic population dynamics and x-ray pulse properties.

Rohringer, N; Santra, R

2008-03-27

50

X-ray interferometer with an x-ray beam splitter  

NASA Astrophysics Data System (ADS)

We report our examination of a new X-ray interferometer for observation of celestial objects and our recent work for preparation of laboratory experiments. The new X-ray interferometer is consisting of two at mirrors and one at beam splitter which are used as grazing incident optics. The aimed wave length is a O-K band or a C-K band. The beam splitter and the mirrors are fabricated by Mo/Si multilayer. We measured their atness and found that the measured atness is acceptable for the test experiment. A pin hole X-ray source is also preparing for a laboratory experiment in order to demonstrate a X-ray interference. We investigated a possible observation of accretion disks around BHs and nearby stars. With a reasonable size of the base line, we can measure their size and possibly we can obtain an evidence of a black hole shadow.

Kitamoto, S.; Sakata, K.; Murakami, H.; Yoshida, Y.; Seta, H.

2012-09-01

51

Intense x-ray machine for penetrating radiography  

SciTech Connect

Penetrating radiography has been used for many years in the nuclear weapons research programs. In frequently penetrating radiography has been used in conventional weapons research programs. For example the Los Alamos PHERMEX machine was used to view uranium rods penetrating steel for the GAU-8 program, and the Ector machine was used to see low-density regions in forming metal jets. The armor/anti-armor program at Los Alamos has created a need for an intense flash x-ray machine that can be dedicated to conventional weapons research. The Balanced Technology Initiative, through DARPA, has funded the design and construction of such a machine at Los Alamos. It will be an 8- to 10-MeV diode machine capable of delivering a dose of 500 R at 1 m with a spot size of less than 5 mm. The machine used an 87.5-stage low-inductance Marx generator that charges up a 7.4-/Omega/, 32-ns water line. The water line is discharged through a self-breakdown oil switch into a 12.4-/Omega/ water line that rings up the voltage into the high-impendance x-ray diode. A long (233-cm) vacuum drift tube is used to separate the large-diameter oil-insulated diode region from the x-ray source area that may be exposed to high overpressures by the explosive experiments. The electron beam is self-focused at the target area using a low-pressure background gas. 15 refs., 11 figs.

Lucht, R.A.; Eckhouse, S.

1989-01-01

52

Electron beam and x-ray resists  

US Patent & Trademark Office Database

Polymers are disclosed comprising a poly(vinyl alcohol) backbone with the following groups or combination of groups bound to the backbone: (A) (substituted alkyl)benzoyl groups; or (B) (substituted alkyl)benzoyl groups, and (vinyl)benzoyl groups; or (C) (substituted alkyl)benzoyl groups, and (halo)benzoyl groups or (2-carboxy-3,4,5,6-tetrachloro) benzoyl groups; (D) (substituted alkyl)benzoyl groups, (vinyl) benzoyl groups, and (halo)benzoyl groups or (2-carboxy-3,4,5,6-tetrachloro)benzoyl groups; (E) (vinyl)benzoyl groups, and (halo)benzoyl groups or (2-carboxy-3,4,5,6-tetrachloro) benzoyl groups; or (F) (halo)benzoyl groups. Each of these polymers can optionally contain, bound to the poly(vinyl alcohol) backbone, (trialkylsily) benzoyl groups. The benzoyl groups are randomly bound to the poly(vinyl alcohol) by ester linkages. Residual pendant hydroxy groups remain after the attachment of the benzoyl groups. Also disclosed are the use of these polymers as radiation sensitive resists, such as, for example, x-ray and/or E-beam resists.

1989-09-19

53

Solar Intensity X-ray and particle Spectrometer (SIXS)  

NASA Astrophysics Data System (ADS)

The Solar Intensity X-ray and particle Spectrometer (SIXS) on the BepiColombo Mercury Planetary Orbiter (MPO) will investigate the direct solar X-rays, and energetic protons and electrons which pass the Spacecraft on their way to the surface of Mercury. These measurements are vitally important for understanding quantitatively the processes that make Mercury's surface glow in X-rays, since all X-rays from Mercury are due to interactions of the surface with incoming highly energetic photons and space particles. The X-ray emission of Mercury's surface will be analysed to understand its structure and composition. SIXS data will also be utilised for studies of the solar X-ray corona, flares, solar energetic particles, and the magnetosphere of Mercury, and for providing information on solar eruptions to other BepiColombo instruments. SIXS consists of two detector subsystems. The X-ray detector system includes three identical GaAs PIN detectors which measure the solar spectrum at 1-20 keV energy range, and their combined field-of-view covers ˜1/4 of the whole sky. The particle detector system consists of an assembly including a cubic central CsI(Tl) scintillator detector with five of its six surfaces covered by a thin Si detector, which together perform low-resolution particle spectroscopy with a rough angular resolution over a field-of-view covering ˜1/4 of the whole sky. The energy range of detected particle spectra is 0.1-3 MeV for electrons and 1-30 MeV for protons. A major task for the SIXS instrument is the measurement of solar X-rays on the dayside of Mercury's surface to enable modeling of X-ray fluorescence and scattering on the planet's surface. Since highly energetic particles are expected to also induce a significant amount of X-ray emission via particle-induced X-ray emission (PIXE) and bremsstrahlung when they are absorbed by the solid surface of the planet Mercury, SIXS performs measurements of fluxes and spectra of protons and electrons. SIXS performs particle measurement at all orbital phases of the MPO as the particle radiation can occur also on the night side of Mercury. The energy ranges, resolutions, and timings of X-ray and particle measurements by SIXS have been adjusted to match with the requirements for interpretation of data from Mercury's surface, to be performed by utilising the data of the Mercury Imaging X-ray Spectrometer (MIXS), which will measure X-ray emission from the surface.

Huovelin, J.; Vainio, R.; Andersson, H.; Valtonen, E.; Alha, L.; Mälkki, A.; Grande, M.; Fraser, G. W.; Kato, M.; Koskinen, H.; Muinonen, K.; Näränen, J.; Schmidt, W.; Syrjäsuo, M.; Anttila, M.; Vihavainen, T.; Kiuru, E.; Roos, M.; Peltonen, J.; Lehti, J.; Talvioja, M.; Portin, P.; Prydderch, M.

2010-01-01

54

LCLS mirror switching of x-ray beam  

NASA Astrophysics Data System (ADS)

The number of proposals for LCLS science has rapidly increased as all six LCLS x-ray instruments have come online. It created rising demand on beam time. Statistics shows that only about 25 % of LCLS proposals can be allocated beam time. One way to increase access is to share the x-ray beam between the different instruments. The purpose of this study is to quickly switch the x-ray beam between the Matter in Extreme Conditions (MEC) Instrument and the Coherent X-ray Imaging (CXI) or X-ray Correlation Spectroscopy (XCS) Instruments, in order that two of the instruments can perform experiments simultaneously. In the most common operational mode, the MEC Instrument uses one x-ray pulse every 10 minutes, limited by the repetition rate of the high power nanosecond laser system. The MEC M3H mirror steers the x-ray beam to the MEC Instrument from the XCS or CXI Instruments. If the M3H mirror could switch the x-ray beam to MEC within a fraction of the 10 minutes waiting time, multiplexing of the x-ray beam would be achieved. The M3H mirror system has two motion stages for translation and rotation. The long path, 230 m, from the mirror to MEC hutch makes the pointing resolution 0f 100 microns and stability requirements challenging. The present study investigates such capabilities by measuring the correlation between the translation speed and the beam pointing reproducibility. We show that mirror translation can multiplex the LCLS x-ray beam.

Yin, J.; Zhang, D.; Arnold, B.; Nagler, B.; Lee, H.; Galtier, E.; Heimann, P.

2013-09-01

55

The low intensity X-ray imaging scope /Lixiscope/  

NASA Technical Reports Server (NTRS)

A fully portable, small-format X-ray imaging system, Lixiscope (low intensity X-ray imaging scope) is described. In the prototype, which has been built to demonstrate the feasibility of the Lixiscope concept, only well-developed and available components have been used. Consideration is given to the principles of operation of the device, some of its performance characteristics as well as possible dental, medical and industrial applications.

Yin, L. I.; Trombka, J. I.; Seltzer, S. M.; Webber, R. L.; Farr, M. R.; Rennie, J.

1978-01-01

56

X-Ray Zone Plates Fabricated Using Electron-Beam and X-Ray Lithography.  

National Technical Information Service (NTIS)

Fresnel zone plate patterns, free of spherical abberation, with diameters of up to 0.63 mm and linewidths as small as 1000 A were fabricated on polyimide-membrane x-ray masks using scanning electron beam lithography Distortion of the electron beam scan ra...

D. C. Shaver D. C. Flanders N. M. Ceglio H. I. Smith

1979-01-01

57

Lateral Distributions of X-ray Intensity and Ablation Pressure on Pellet Shells Irradiated by External X-ray Sources  

Microsoft Academic Search

The lateral distributions of the X-ray intensity and the ablation pressure on a pellet surface were calculated for the pellet implosion driven by soft X-rays emitted from external X-ray sources. The lateral ablation pressure distribution calculated by ray-tracing with the ablation pressure scaling is in good agreement with that obtained experimentally.

Shuji Sakabe

1988-01-01

58

Laboratory-based micro-X-ray fluorescence setup using a von Hamos crystal spectrometer and a focused beam X-ray tube.  

PubMed

The high-resolution von Hamos bent crystal spectrometer of the University of Fribourg was upgraded with a focused X-ray beam source with the aim of performing micro-sized X-ray fluorescence (XRF) measurements in the laboratory. The focused X-ray beam source integrates a collimating optics mounted on a low-power micro-spot X-ray tube and a focusing polycapillary half-lens placed in front of the sample. The performances of the setup were probed in terms of spatial and energy resolution. In particular, the fluorescence intensity and energy resolution of the von Hamos spectrometer equipped with the novel micro-focused X-ray source and a standard high-power water-cooled X-ray tube were compared. The XRF analysis capability of the new setup was assessed by measuring the dopant distribution within the core of Er-doped SiO2 optical fibers. PMID:24784587

Kayser, Y; B?achucki, W; Dousse, J-Cl; Hoszowska, J; Neff, M; Romano, V

2014-04-01

59

Diffraction imaging of crystals with focused x-ray beams  

SciTech Connect

We describe an imaging technique based on diffraction of a focused x-ray beam in crystals. A focused beam is formed by a zone plate and Bragg diffracted from a crystalline sample positioned between the zone plate and the focus. The intensity pattern is recorded by a high-resolution charge-coupled-device detector placed in the focus. Diffraction images recorded from perfect Si and GaAs crystals for various reflections demonstrate the broadening of the focused beam due to a finite scattering length. The images from semiconductor epitaxial films and heterostructures show additional peaks originating from the interfaces with their spatial position corresponding to the depth from the surface. Diffraction images from isolated defects in Si crystal demonstrate capabilities to study bulk defects. Theoretical simulations for perfect crystals show excellent agreement with experiments. We demonstrate that the new imaging technique is depth sensitive and combines structural sensitivity of traditional x-ray topography methods with spatial in-plane resolution provided by focusing.

Kazimirov, A. [CHESS, Cornell University, Ithaca, New York 14853 (United States); Kohn, V. G. [Russian Research Center 'Kurchatov Institute', 123182 Moscow (Russian Federation); Cai, Z.-H. [Advanced Photon Source, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States)

2010-06-01

60

High-intensity X-ray microbeams obtained using a cylindrical polycapillary structure  

Microsoft Academic Search

High-intensity quasi-parallel X-ray microbeams with a radiation flux density on the order of 1010 photon\\/(s mm2) and a divergence of several milliradians, which is close to the parameters of synchrotron radiation, were obtained using\\u000a a microfocus source based on a transmission-type X-ray tube. The divergent X-ray radiation was converted into a quasi-parallel\\u000a beam using a cylindrical structure of Kumakhov polycapillary

A. Y. Romanov; I. V. Dmitriev

2004-01-01

61

Use of capillary optics as a beam intensifier for a Compton x-ray source.  

PubMed

The use of Kumakhov capillary optics will significantly enhance the performance of near-monochromatic, Compton backscattered x-ray programs. The Vanderbilt University Medical Free-Electron Laser Center is developing the capability to create these tunable x rays for medical imaging. The present transport has only reflection optics, and the beam is quite large in diameter at the laboratory. Low loss collimation of this beam would allow higher x-ray intensities after transport. This article describes experimental and computer simulation results which predict the expected performance for a multifiber Kumakhov collimator for use in the x-ray beam transport. Estimates from our research are that a multifiber optic formed of individual polycapillary fibers could be used to capture the full 7 mrad of the Vanderbilt x-ray beam and collimate it to a 1-2 mrad divergence with approximately 40%-50% transmission efficiency. This optic should increase the x-ray intensity at the laboratory level by a factor of > or = 5 by decreasing the beam divergence and subsequent spot size. Additionally, analysis of monolithic optics of fused multicapillary fibers predicts an increase in the intensity of the x rays at the laboratory by a factor of 55. These optics can have tapered channels that greatly decrease their exit divergence. This will greatly enhance the capabilities of this unique x-ray source. This article reports the initial results from a collaboration between Vanderbilt, The Center for X-Ray Optics at University at Albany, SUNY, and X-Ray Optical Systems in Albany, NY. PMID:7891640

Tompkins, P A; Abreu, C C; Carroll, F E; Xiao, Q F; MacDonald, C A

1994-11-01

62

X-ray beam size measurements on the Advanced Test Accelerator  

SciTech Connect

The electron beam size has been determined on the Advanced Test Accelerator (ATA) by intercepting the beam with a target and measuring the resulting x-ray intensity as a function of time as the target is moved through the beam. Several types of targets have been used. One is a tantalum rod which extends completely across the drift chamber. Another is a tungsten powder filled carbon crucible. Both of these probes are moved from shot to shot so that the x-ray signal intensity varies with probe position. A third is a larger tantalum disk which is inserted on beam axis to allow determining beam size on a one shot basis. The x-ray signals are detected with an MCP photomultiplier tube located at 90/sup 0/ to the beamline. It is sufficiently shielded to reject background x-rays and neutrons. The signals were digitized, recorded and later unfolded to produce plots of x-ray intensity versus probe position for several times during the pulse. The presumption that the x-ray intensity is proportional to beam current density is checked computationally. Details of the probe construction and PMT shielding, as well as sample measurements are given.

Struve, K.W.; Chambers, F.W.; Lauer, E.J.; Slaughter, D.R.

1986-01-01

63

New X-ray beam position monitors with submicron resolution utilizing imaging of scattered X-rays at CHESS  

NASA Astrophysics Data System (ADS)

At CHESS' A, F and G wiggler beam lines three new video beam position monitors (VBPMs) have been commissioned. These new VBPMs utilize X-rays scattered from the graphite filter (A and F line) or from a beryllium window (G-line) as the white wiggler beam passes through them. As the X-rays scatter in all directions from the scattering medium, a slit camera creates an image of the beam's footprint on a fluorescent screen. This image is then viewed by a CCD camera and analyzed using a computer program to calculate the intensity centroid, the beam profile and integrated intensity. These data are delivered to the CHESS signal archiving system for storage and display. The new systems employ digital cameras. These cameras are free of the noise inherent to the analog systems with long video signal connections. As a result, the beam position data delivered by the new systems are more reliable and accurate as shown by beam position traces using different beam position monitors on the same beam line.

Revesz, Peter; Temnykh, Alexander B.; Pauling, Alan K.

2011-09-01

64

Potential applications of polycapillary optics to polarized beam X-ray fluorescence analysis  

Microsoft Academic Search

The Polarized beam X-ray fluorescence (XRF) technique has potential applications in elemental analysis in materials analysis and in-vivo. In this work, first micro X-ray fluorescence (MXRF) measurements were done using a focusing lens. Polarization can be used to reduce the background, to give a better minimum detection limit. Polarizing the beam, using scattering has a disadvantage of low intensity and

Abrar M. Hussain

2006-01-01

65

Multi-Beam Compton Scattering Monochromatic Tunable Hard X-Ray Source  

NASA Astrophysics Data System (ADS)

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo (UTNS). Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35 MeV electron beam and 2.5 J/10 nsec Nd:YAG laser. In order to increase the efficiency of the X-ray yield, we adopt a laser pulse circulation system. In our case, the laser pulse circulation system can increase the X-ray intensity of up to 50 times. Main features of our scheme are to produce monochromatic tunable hard (10-40 keV) X-rays with the intensities of 108-109 photons/sec. In addition, X-ray energy can be changed with rapidly by 40 ms by introducing two different wavelength lasers (YAG fundamental (1064 nm), 2nd harmonic (532 nm)) and optical switch. This quick energy change is indispensable to living specimens and very difficult by a large SR light source and others. We designed a laser pulse circulation system to increase the X-ray yield 10 times higher (up to 108 photons/RF pulse, 109 photons/sec). It can be proved that the laser total increases 10 times higher by principle experiment with lower energy laser (25 mJ/pulse). Dual-energy X-ray CT and subtraction X-ray CT are available to determine 3D distribution of atomicc number density and electron density, and specified atomic distribution, respectively. Here, the construction status of the X-band beam line and the application plan of the hard X-ray will be reported.

Uesaka, Mitsuru; Sakamoto, Fumito; Fukasawa, Atsushi; Ogino, Haruyuki; Yamamoto, Tomohiko; Meng, De; Dobashi, Katsuhiro; Miyoshi, Toshinobu; Higo, Toshiyasu; Akemoto, Mitsuo; Urakawa, Junji

66

Characterization of X-ray generator beam profiles.  

SciTech Connect

T to compute the radiography properties of various materials, the flux profiles of X-ray sources must be characterized. This report describes the characterization of X-ray beam profiles from a Kimtron industrial 450 kVp radiography system with a Comet MXC-45 HP/11 bipolar oil-cooled X-ray tube. The empirical method described here uses a detector response function to derive photon flux profiles based on data collected with a small cadmium telluride detector. The flux profiles are then reduced to a simple parametric form that enables computation of beam profiles for arbitrary accelerator energies.

Mitchell, Dean James; Harding, Lee T.; Thoreson, Gregory G.; Theisen, Lisa Anne; Parmeter, John Ethan; Thompson, Kyle Richard

2013-07-01

67

An x-ray technique for precision laser beam synchronization  

Microsoft Academic Search

A new x-ray technique for recording the relative arrival times of multiple laser beams at a common target with better than ±10-ps accuracy has been implemented at the Nova laser facility. 80-ps, 3? Nova beams are focused to separate locations on a gold ribbon target viewed from the side. The measurement consists of using well-characterized reentrant x-ray streak cameras for

O. L. Landen; R. A. Lerche; R. G. Hay; B. A. Hammel; D. Kalantar; M. D. Cable

1995-01-01

68

An x-ray technique for precision laser beam synchronization  

Microsoft Academic Search

A new x-ray technique for recording the relative arrival times of multiple laser beams at a common target with better than [plus minus]10-ps accuracy has been implemented at the Nova laser facility. 80-ps, 3[omega] Nova beams are focused to separate locations on a gold ribbon target viewed from the side. The measurement consists of using well-characterized reentrant x-ray streak cameras

O. L. Landen; R. A. Lerche; R. G. Hay; B. A. Hammel; D. Kalantar; M. D. Cable

1995-01-01

69

Ultrafast absorption of intense x rays by nitrogen molecules  

NASA Astrophysics Data System (ADS)

We devise a theoretical description for the response of nitrogen molecules (N2) to ultrashort and intense x rays from the free electron laser Linac Coherent Light Source (LCLS). We set out from a rate-equation description for the x-ray absorption by a nitrogen atom. The equations are formulated using all one-x-ray-photon absorption cross sections and the Auger and radiative decay widths of multiply-ionized nitrogen atoms. Cross sections are obtained with a one-electron theory and decay widths are determined from ab initio computations using the Dirac-Hartree-Slater (DHS) method. We also calculate all binding and transition energies of nitrogen atoms in all charge states with the DHS method as the difference of two self-consistent field (SCF) calculations (?SCF method). To describe the interaction with N2, a detailed investigation of intense x-ray-induced ionization and molecular fragmentation are carried out. As a figure of merit, we calculate ion yields and the average charge state measured in recent experiments at the LCLS. We use a series of phenomenological models of increasing sophistication to unravel the mechanisms of the interaction of x rays with N2: a single atom, a symmetric-sharing model, and a fragmentation-matrix model are developed. The role of the formation and decay of single and double core holes, the metastable states of N22+, and molecular fragmentation are explained.

Buth, Christian; Liu, Ji-Cai; Chen, Mau Hsiung; Cryan, James P.; Fang, Li; Glownia, James M.; Hoener, Matthias; Coffee, Ryan N.; Berrah, Nora

2012-06-01

70

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter  

Microsoft Academic Search

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense

FRANK E. CARROLL; JAMES W. WATERS; RON R. PRICE; CHARLES A. BRAU; CARLTON F. ROOS; NORMAN H. TOLK; DAVID R. PICKENS; W. HOYT STEPHENS

1990-01-01

71

Quantitative measurement of hard x-ray spectra for high intensity laser produced plasma.  

PubMed

X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was calibrated using pre-characterized laser-produced x-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for x-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency for specific x-ray line emissions, is derived as a consequence of this work. PMID:22667617

Zhang, Z; Nishimura, H; Namimoto, T; Fujioka, S; Arikawa, Y; Nishikino, M; Kawachi, T; Sagisaka, A; Hosoda, H; Orimo, S; Ogura, K; Pirozhkov, A; Yogo, A; Okano, Y; Kiriyama, H; Kondo, K; Ohshima, S; Azechi, H

2012-05-01

72

Quantitative measurement of hard x-ray spectra for high intensity laser produced plasma  

SciTech Connect

X-ray line spectra ranging from 17 to 77 keV were quantitatively measured with a Laue spectrometer, composed of a cylindrically curved crystal and a detector. Either a visible CCD detector coupled with a CsI phosphor screen or an imaging plate can be chosen, depending on the signal intensities and exposure times. The absolute sensitivity of the spectrometer system was calibrated using pre-characterized laser-produced x-ray sources and radioisotopes. The integrated reflectivity for the crystal is in good agreement with predictions by an open code for x-ray diffraction. The energy transfer efficiency from incident laser beams to hot electrons, as the energy transfer agency for specific x-ray line emissions, is derived as a consequence of this work.

Zhang, Z.; Nishimura, H.; Namimoto, T.; Fujioka, S.; Arikawa, Y.; Hosoda, H.; Azechi, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishikino, M.; Kawachi, T.; Sagisaka, A.; Orimo, S.; Ogura, K.; Pirozhkov, A.; Yogo, A.; Kiriyama, H.; Kondo, K. [Quantum Beam Science Directorate, Kansai Photon Science Institute, JAEA, Kyoto 619-0215 (Japan); Okano, Y. [Laser Research Center for Molecular Science, Institute for Molecular Science, National Institute of Natural Science 38 Nishigo-Naka, Myodaiji, Okazaki 444-8585 (Japan); Ohshima, S. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Pioneering Research Unit for Next Generation, Kyoto University, Uji 611-0011 (Japan)

2012-05-15

73

Parametric X-ray radiation as a beam size monitor  

NASA Astrophysics Data System (ADS)

We propose two new approaches, referred to as the local and remote methods, for measuring electron beam sizes using parametric X-ray radiation. Using the local method, we have carried out a proof-of-principle experiment, and good agreement was obtained with the results of a standard method using a fluorescent screen. For the remote method, we have proposed a scheme to measure beam sizes using a Fresnel zone plate as an X-ray lens. These methods may prove useful for measuring the sizes of electron beams with small emittances or short bunch lengths in recent advanced accelerators.

Takabayashi, Y.

2012-07-01

74

X-ray Intensity Fluctuation Spectroscopy Using Nanofocused Hard X-rays: Its Application to Study of Relaxor Ferroelectrics  

NASA Astrophysics Data System (ADS)

The use of a combination of coherent X-rays from a third-generation synchrotron light source and ultraprecise Kirkpatrick-Baez mirrors enables us to apply nanofocused hard X-rays in solid-state physics. We developed an apparatus for X-ray intensity fluctuation spectroscopy using the nanofocused hard X-rays and applied it to the study of relaxor ferroelectrics. We have successfully detected a large and slow intensity fluctuation of scattered X-rays above cubic-to-tetragonal phase transition temperature with a characteristic time scale on the order of 10 s. We speculated that the intensity fluctuation originates from domain number fluctuation, which is directly related to the dielectric response, particularly the frequency dispersion.

Kenji Ohwada,; Kazumichi Namikawa,; Susumu Shimomura,; Hironori Nakao,; Hidekazu Mimura,; Kazuto Yamauchi,; Mitsuyoshi Matsushita,; Jun'ichiro Mizuki,

2010-02-01

75

An x ray technique for precision laser beam synchronization  

Microsoft Academic Search

A new x-ray technique for recording the relative arrival times of multiple laser beams at a common target with better than +\\/- 10 ps accuracy has been implemented at the Nova laser facility. 100 ps, 3(omega) Nova beam are focused to separate locations on a gold ribbon target viewed from the side. The measurement consists of using well characterized re-entrant

O. L. Landen; R. A. Lerche; R. G. Hay; B. A. Hammel; D. Kalantar; M. D. Cable

1994-01-01

76

Relationship between x-ray illumination field size and flat field intensity and its impacts on x-ray imaging  

SciTech Connect

Purpose: X-ray cone-beam CT (CBCT) is being increasingly used for various clinical applications, while its performance is still hindered by image artifacts. This work investigates a new source of reconstruction error, which is often overlooked in the current CBCT imaging. The authors find that the x-ray flat field intensity (I{sub 0}) varies significantly as the illumination volume size changes at different collimator settings. A wrong I{sub 0} value leads to inaccurate CT numbers of reconstructed images as well as wrong scatter measurements in the CBCT research. Methods: The authors argue that the finite size of x-ray focal spot together with the detector glare effect cause the I{sub 0} variation at different illumination sizes. Although the focal spot of commercial x-ray tubes typically has a nominal size of less than 1 mm, the off-focal-spot radiation covers an area of several millimeters on the tungsten target. Due to the large magnification factor from the field collimator to the detector, the penumbra effects of the collimator blades result in different I{sub 0} values for different illumination field sizes. Detector glare further increases the variation, since one pencil beam of incident x-ray is scattered into an area of several centimeters on the detector. In this paper, the authors study these two effects by measuring the focal spot distribution with a pinhole assembly and the detector point spread function (PSF) with an edge-spread function method. The authors then derive a formula to estimate the I{sub 0} value for different illumination field sizes, using the measured focal spot distribution and the detector PSF. Phantom studies are carried out to investigate the accuracy of scatter measurements and CT images with and without considering the I{sub 0} variation effects. Results: On our tabletop system with a Varian Paxscan 4030CB flat-panel detector and a Varian RAD-94 x-ray tube as used on a clinical CBCT system, the focal spot distribution has a measured full-width-at-half-maximum (FWHM) of around 0.4 mm, while non-negligible off-focal-spot radiation is observed at a distance of over 2 mm from the center. The measured detector PSF has an FWHM of 0.510 mm, with a shape close to Gaussian. From these two distributions, the author calculate the estimated I{sub 0} values at different collimator settings. The I{sub 0} variation mainly comes from the focal spot effect. The estimation matches well with the measurements at different collimator widths in both horizontal and vertical directions, with an average error of less than 3%. Our method improves the accuracy of conventional scatter measurements, where the scatter is measured as the difference between fan-beam and cone-beam projections. On a uniform water cylinder phantom, more accurate I{sub 0} suppresses the unfaithful high-frequency signals at the object boundaries of the measured scatter, and the SPR estimation error is reduced from 0.158 to 0.014. The proposed I{sub 0} estimation also reduces the reconstruction error from about 20 HU on the Catphan Copyright-Sign 600 phantom in the selected regions of interest to less than 4 HU. Conclusions: The I{sub 0} variation is identified as one additional error source in x-ray imaging. By measuring the focal-spot distribution and detector PSF, the authors propose an accurate method of estimating the I{sub 0} value for different illumination field sizes. The method obtains more accurate scatter measurements and therefore facilitates scatter correction algorithm designs. As correction methods for other CBCT artifacts become more successful, our research is significant in further improving the CBCT imaging accuracy.

Dong Xue; Niu Tianye; Jia Xun; Zhu Lei [Nuclear and Radiological Engineering and Medical Physics Programs, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Department of Radiation Medicine and Applied Sciences, Center for Advanced Radiotherapy Technologies, University of California, San Diego, La Jolla, California 92093 (United States); Nuclear and Radiological Engineering and Medical Physics Programs, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2012-10-15

77

Interpretation of nanoparticle X-ray photoelectron intensities  

NASA Astrophysics Data System (ADS)

X-ray photoelectron (XPS) intensities have been simulated for spherical core-shell nanoparticles (NPs) in different geometrical arrangements in order to investigate the validity of commonly made assumptions for the interpretation of XPS NP intensities. The single-sphere approximation is valid for a powder sample when all spatial coordinates of the NP positions are uncorrelated. Correlations along either the depth coordinate or the lateral coordinates lead to features in the angular distribution that provide information on these correlations. The XPS intensity is proportional to the surface-to-volume ratio of nanoparticles but only for NP sizes exceeding the inelastic mean free path of the photoelectrons.

Werner, Wolfgang S. M.; Chudzicki, Maksymillian; Smekal, Werner; Powell, Cedric J.

2014-06-01

78

Influence of temperature on parametric x-ray intensity  

Microsoft Academic Search

We have measured the temperature dependence of parametric x-ray radiation (PXR) from a Si single crystal bombarded by 900-MeV electrons. The radiation intensity is appreciably enhanced when the crystal is cooled to liquid-nitrogen temperature as compared with the case for room temperature. The enhancement factors are larger for the higher-order reflections and are quantitatively consistent with the assumption that the

K. Yu. Amosov; B. N. Kalinin; A. P. Potylitsin; V. P. Sarychev; S. R. Uglov; V. A. Verzilov; S. A. Vorobiev; I. Endo; T. Kobayashi

1993-01-01

79

Monitoring x-ray beam damage on lipid films by an integrated Brewster angle microscope/x-ray diffractometer  

SciTech Connect

We describe an integrated Brewster angle microscope (BAM), Langmuir trough, and grazing incidence x-ray diffraction assembly. The integration of these three techniques allows for the direct observation of radiative beam damage to a lipid monolayer at the air-water interface. Although beam damage has been seen in x-ray measurements, it has not been directly observed in situ at the micron scale. Using this integrated assembly, we examined the effects of radiative beam damage on Langmuir monolayers of 1,2-dimyristoyl-sn-glycero-3-[phospho-L-serine] (DMPS), 1:1 DMPS:1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, and 1:1 DMPS:1,2-dioleoyl-sn-glycero-3-phosphocholine held at a constant surface pressure. For constant surface pressure experiments, we observed a marked decrease in the surface area of the film upon exposure to the beam due to photodissociation. For a condensed lipid film, a change in refractive index of the film was observed post-beam-exposure, indicating areas of damage. For DMPS in an oxygenated environment, the Bragg peak intensity decreased with beam exposure. In mixed monolayer systems, with saturated and unsaturated lipids, an increase in the number of small saturated lipid domains was seen as the unsaturated lipid was preferentially damaged and lost from the monolayer. We show that BAM is a highly effective technique for in situ observation of the effects of radiative damage at the air/water interface during a synchrotron experiment.

Danauskas, Stephen M.; Ratajczak, Maria K.; Ishitsuka, Yuji; Gebhardt, Jeffrey; Schultz, David; Meron, Mati; Lin Binhua; Lee, Ka Yee C. [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); Institute for Biophysical Dynamics, University of Chicago, Chicago, Illinois 60637 (United States) and James Franck Institute, University of Chicago, Chicago, Illinois 60637 (United States); Department of Physics, University of Chicago, Chicago, Illinois 60637 (United States); Consortium for Advanced Radiation Sources, University of Chicago, Chicago, Illinois 60637 (United States)

2007-10-15

80

X-ray beam method for displacement measurement in hostile environments  

NASA Technical Reports Server (NTRS)

A new method of extensometry using an X-ray beam was devised, and the results of current testing reveal it to be highly feasible. This technique has been shown to provide a non-contacting system that is immune to problems associated with density variations in gaseous environments, that plague currently available optical methods. This advantage is a result of the non-refracting penetrating nature of X-rays. The method is based on X-ray-induced X-ray fluorescence of targets, which subsequently serve as fudicial markers. Some target materials have melting points over 1600 degrees C which will facilitate measurement at extremely high temperatures. A highly focused intense X-ray beam, which is produced using a Johansen 'bent crystal', is then scanned across the target, which responds by fluorescing X-rays when stimulated by the incident beam. This secondary radiation is monitored using a detector. By carefully measuring beam orientation, change in target edge position can be determined. Many variations on this basic theme are now possible such as two targets demarcating a gage length, or a beam shadowing method using opaque targets.

Jordan, Eric H.; Pease, D. M.; Canistraro, H.; Brew, Dale

1989-01-01

81

Nonlinear Atomic Response to Intense Ultrashort X Rays  

SciTech Connect

The nonlinear absorption mechanisms of neon atoms to intense, femtosecond kilovolt x rays are investigated. The production of Ne{sup 9+} is observed at x-ray frequencies below the Ne{sup 8+}, 1s{sup 2} absorption edge and demonstrates a clear quadratic dependence on fluence. Theoretical analysis shows that the production is a combination of the two-photon ionization of Ne{sup 8+} ground state and a high-order sequential process involving single-photon production and ionization of transient excited states on a time scale faster than the Auger decay. We find that the nonlinear direct two-photon ionization cross section is orders of magnitude higher than expected from previous calculations.

Doumy, G. [Ohio State University, Columbus, Ohio 43210 (United States)] [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Roedig, C.; Blaga, C. I.; DiChiara, A. D.; Agostini, P.; DiMauro, L. F. [Ohio State University, Columbus, Ohio 43210 (United States); Son, S.-K. [Center for Free-Electron Laser Science, DESY, 22607 Hamburg (Germany); Santra, R. [Center for Free-Electron Laser Science, DESY, 22607 Hamburg (Germany)] [Department of Physics, University of Hamburg, 20355 Hamburg (Germany); Berrah, N.; Fang, L.; Hoener, M. [Western Michigan University, Kalamazoo, Michigan 49008 (United States); Bostedt, C.; Bozek, J. D.; Messerschmidt, M. [Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Bucksbaum, P. H.; Cryan, J. P.; Ghimire, S.; Glownia, J. M.; Reis, D. A. [Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Kanter, E. P. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2011-02-25

82

Beam optics of exploding foil plasma x-ray lasers  

SciTech Connect

In soft x-ray lasers, amplification is achieved as the x rays propagate down a long narrow plasma column. Refraction, due to electron density gradients, tends to direct the x-rays out of high density regions. This can have the undesirable effect of shortening the distance that the x ray stay within the plasma, thereby limiting the amount of amplification. The exploding foil design lessens refraction, but does not eliminate it. In this paper, a quantitative analysis of propagation and amplification in an exploding foil x-ray laser is presented. The density and gain profiles within the plasma are modeled in an approximate manner, which enables considerable analytic progress. It is found that refraction introduces a loss term to the laser amplification. The beam pattern from a parabolic gain profile laser has a dominant peak on the x-ray laser axis. The pattern from a quartic gain profile having a dip on-axis can produce a profile with off-axis peaks, in better agreement with recent experimental data.

London, R.A.

1988-01-01

83

Monolithic focused reference beam X-ray holography  

PubMed Central

Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot imaging at coherent X-ray sources. In its common implementation, the image contrast is limited by the reference signal generated by a small pinhole aperture. Increased pinhole diameters improve the signal, whereas the resolution is diminished. Here we report a new concept to decouple the spatial resolution from the image contrast by employing a Fresnel zone plate to provide the reference beam. Superimposed on-axis images of distinct foci are separated with a novel algorithm. Our method is insensitive to mechanical drift or vibrations and allows for long integration times common at low-flux facilities like high harmonic generation sources. The application of monolithic focused reference beams improves the efficiency of high-resolution X-ray Fourier transform holography beyond all present approaches and paves the path towards sub-10?nm single-shot X-ray imaging.

Geilhufe, J.; Pfau, B.; Schneider, M.; Buttner, F.; Gunther, C. M.; Werner, S.; Schaffert, S.; Guehrs, E.; Frommel, S.; Klaui, M.; Eisebitt, S.

2014-01-01

84

Monolithic focused reference beam X-ray holography.  

PubMed

Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot imaging at coherent X-ray sources. In its common implementation, the image contrast is limited by the reference signal generated by a small pinhole aperture. Increased pinhole diameters improve the signal, whereas the resolution is diminished. Here we report a new concept to decouple the spatial resolution from the image contrast by employing a Fresnel zone plate to provide the reference beam. Superimposed on-axis images of distinct foci are separated with a novel algorithm. Our method is insensitive to mechanical drift or vibrations and allows for long integration times common at low-flux facilities like high harmonic generation sources. The application of monolithic focused reference beams improves the efficiency of high-resolution X-ray Fourier transform holography beyond all present approaches and paves the path towards sub-10?nm single-shot X-ray imaging. PMID:24394675

Geilhufe, J; Pfau, B; Schneider, M; Büttner, F; Günther, C M; Werner, S; Schaffert, S; Guehrs, E; Frömmel, S; Kläui, M; Eisebitt, S

2014-01-01

85

Monolithic focused reference beam X-ray holography  

NASA Astrophysics Data System (ADS)

Fourier transform holography is a highly efficient and robust imaging method, suitable for single-shot imaging at coherent X-ray sources. In its common implementation, the image contrast is limited by the reference signal generated by a small pinhole aperture. Increased pinhole diameters improve the signal, whereas the resolution is diminished. Here we report a new concept to decouple the spatial resolution from the image contrast by employing a Fresnel zone plate to provide the reference beam. Superimposed on-axis images of distinct foci are separated with a novel algorithm. Our method is insensitive to mechanical drift or vibrations and allows for long integration times common at low-flux facilities like high harmonic generation sources. The application of monolithic focused reference beams improves the efficiency of high-resolution X-ray Fourier transform holography beyond all present approaches and paves the path towards sub-10nm single-shot X-ray imaging.

Geilhufe, J.; Pfau, B.; Schneider, M.; Büttner, F.; Günther, C. M.; Werner, S.; Schaffert, S.; Guehrs, E.; Frömmel, S.; Kläui, M.; Eisebitt, S.

2014-01-01

86

Potential applications of polycapillary optics to polarized beam X-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

The Polarized beam X-ray fluorescence (XRF) technique has potential applications in elemental analysis in materials analysis and in-vivo. In this work, first micro X-ray fluorescence (MXRF) measurements were done using a focusing lens. Polarization can be used to reduce the background, to give a better minimum detection limit. Polarizing the beam, using scattering has a disadvantage of low intensity and white beam background. Beam polarized by diffraction after collimating lens gives better results. A suitable crystal satisfying Bragg's condition gives a monochromatic as well as polarized beam with good intensity. Using a polycapillary lens increases the intensity of the X-ray beam using a laboratory based X-ray source with compact experimental set-up. Experimental results confirm the decrease in background in the polarization direction and the improvement in minimum detectable limit using the polarized beam. Verification of calculated results from measurements allows optimization of a laboratory based system with respect to source, lens and geometry parameters. MDL as low as ppm for bulk samples are predicted.

Hussain, Abrar M.

87

X-ray reference-intensity and X-ray fluorescence analyses of Salton Sea core  

Microsoft Academic Search

Quantitative X-ray powder diffraction (XRD) and X-ray transmission (XRT) procedures have been combined with X-ray fluorescence (XRF) and other spectroscopic methods to characterize the mineralogy and chemistry of 33 core samples obtained from the Salton Sea Scientific Drilling Program (SSSDP) well. Major mineral components in the SSSDP samples include quartz, orthoclase, sodic plagioclase, chlorite, epidote, illite, and calcite, with minor

B. L. Davis; C. K. Jr. Shearer; S. B. Simon; M. N. Spilde; J. J. Papike; J. C. Laul

2009-01-01

88

X-ray divergent-beam (Kossel) technique: A review  

SciTech Connect

The development of the X-ray divergent-beam (Kossel) technique over the last 50 years is traced. The fundamentals of this technique and ways to implement it experimentally are considered, and its potential for studying the real structure of crystals is analyzed in detail.

Lider, V. V., E-mail: lider@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

2011-03-15

89

Generation and application of the soft X-ray laser beam based on capillary discharge  

NASA Astrophysics Data System (ADS)

In this work we report on the generation and characterization of a focused soft X-ray laser beam with intensity and energy density that exceed the threshold for the ablation of PMMA. We demonstrate a feasibility of direct ablation of holes using a focused soft X-ray laser beam. Ablated craters in PMMA/gold-covered-PMMA samples were obtained by focusing the soft X-ray Ar8+ laser pulses generated by a 46.9 nm tabletop capillary-discharge-pumped driver with a spherical Si/Sc multilayer mirror. It was found that the focused beam is capable by one shot to ablate PMMA, even if the focus is significantly influenced by astigmatism. Analysis of the laser beam footprints by atomic force microscope shows that ablated holes have periodic surface structure (similarly as Laser-Induced Periodic Surface Structure) with period ~2,8 ?m and with peak-to-peak depth ~5-10 nm.

Frolov, Oleksandr; Kolacek, Karel; Straus, Jaroslav; Schmidt, Jiri; Prukner, Vaclav; Shukurov, Andrey

2014-05-01

90

The effect of the dc bias voltage on the x-ray bremsstrahlung and beam intensities of medium and highly charged ions of argon.  

PubMed

X-ray bremsstrahlung measurements from the 18 GHz High Temperature Superconducting Electron Cyclotron Resonance Ion Source, Pantechnik-Delhi Ion Source were measured as a function of negative dc bias voltage, keeping all other source operating parameters fixed and the extraction voltage in the off condition. The optimization of medium and highly charged ions of argon with similar source operating parameters is described. It is observed that the high temperature component of the electron is altered significantly with the help of bias voltage, and the electron population has to be maximized for obtaining higher current. PMID:20192344

Rodrigues, G; Lakshmy, P S; Baskaran, R; Kanjilal, D; Roy, A

2010-02-01

91

Development of confocal micro X-ray fluorescence instrument using two X-ray beams  

Microsoft Academic Search

A new confocal micro X-ray fluorescence instrument was developed. This instrument has two independent micro X-ray tubes with Mo targets. A full polycapillary X-ray lens was attached to each X-ray tube. Another half polycapillary lens was attached to a silicon drift X-ray detector (SDD). The focal spots of the three lenses were adjusted to a common position. The effects of

Kouichi Tsuji; Kazuhiko Nakano; Xunliang Ding

2007-01-01

92

Bessel spatial profile of a soft x-ray laser beam  

SciTech Connect

We report far-field profile measurements of an optical-field-ionized high-order harmonic-seeded soft x-ray laser. We show that the beam transverse profile can be controlled between a regular Gaussian shape and a Bessel profile exhibiting several rings via the infrared laser pump intensity. These experimental data are supported by a complete numerical modeling including a two-dimensional plasma amplifier simulation and a two-level soft x-ray amplification using a Maxwell-Bloch treatment. This model takes into account the experimental high-order harmonic wavefront and intensity before it is numerically amplified.

Tissandier, F.; Sebban, S.; Ribiere, M.; Gautier, J.; Zeitoun, Ph.; Lambert, G.; Goddet, J.-Ph.; Burgy, F.; Valentin, C.; Rousse, A. [Laboratoire d'Optique Appliquee, ENSTA Paristech/Ecole Polytechnique/CNRS, UMR 7639, F-91761 Palaiseau Cedex (France); Nejdl, J.; Mocek, T. [Institute of Physics, ASCR, Na Slovance 2, CZ-182 21 Prague 8 (Czech Republic); Maynard, G. [Laboratoire de Physique des Gaz et des Plasmas, Universite Paris Sud/CNRS, UMR 8578, F-91405 Orsay Cedex (France)

2010-12-06

93

Motorized Beam Alignment of a Commercial X-ray Diffractometer  

NASA Technical Reports Server (NTRS)

X-ray diffraction (XRD) is a powerful analysis method that allows researchers to noninvasively probe the crystalline structure of a material. This includes the ability to determine the crystalline phases present, quantify surface residual stresses, and measure the distribution of crystallographic orientations. The Structures and Materials Division at the NASA Glenn Research Center (GRC) heavily uses the on-site XRD lab to characterize advanced metal alloys, ceramics, and polymers. One of the x-ray diffractometers in the XRD lab (Bruker D8 Discover) uses three different x-ray tubes (Cu, Cr, and Mn) for optimal performance over numerous material types and various experimental techniques. This requires that the tubes be switched out and aligned between experiments. This alignment maximizes the x-ray tube s output through an iterative process involving four set screws. However, the output of the x-ray tube cannot be monitored during the adjustment process due to standard radiation safety engineering controls that prevent exposure to the x-ray beam when the diffractometer doors are open. Therefore, the adjustment process is a very tedious series of blind adjustments, each followed by measurement of the output beam using a PIN diode after the enclosure doors are shut. This process can take up to 4 hr to perform. This technical memorandum documents an in-house project to motorize this alignment process. Unlike a human, motors are not harmed by x-ray radiation of the energy range used in this instrument. Therefore, using motors to adjust the set screws will allow the researcher to monitor the x-ray tube s output while making interactive adjustments from outside the diffractometer. The motorized alignment system consists of four motors, a motor controller, and a hand-held user interface module. Our goal was to reduce the alignment time to less than 30 min. The time available was the 10-week span of the Lewis' Educational and Research Collaborative Internship Project (LERCIP) summer internship program and the budget goal was $1200. In this report, we will describe our motorization design and discuss the results of its implementation.

Van Zandt, Noah R.; Myers, James F.; Rogers, Richard B

2013-01-01

94

Development of polarized and monochromatic x-ray beams from tube sources  

NASA Astrophysics Data System (ADS)

The development of sources and optics has allowed the migration of techniques originally developed for synchrotron beam lines to field, industrial and clinical applications. For example, monochromatic beams produced with synchrotron sources are known to give higher contrast for mammography than clinical broadband sources. However, clinical sources with very narrow energy bandwidth, produced for example with flat monochromator crystals, tend to have limited intensity and field of view. Doubly curved crystal x-ray optics can provide intense focused monochromatic fan beams from laboratory x-ray tube sources. These optics are routinely employed in crystallography and x-ray fluorescence, however, careful analysis is required to assess whether the focused beam creates unacceptable divergence and hence poor spatial resolution in imaging. The intensity and resolution of the focused beam were measured and compared to simulation results. The measurements and simulations were in good agreement, allowing for system design to provide the required resolution. High efficiency collimating optics coupled with diffracting crystals also can produce relatively high intensity and resolution. For both methods, monochromatization occurs before the patient, resulting in a potential dose reduction as well as significant measured contrast enhancement. If the diffraction angle is chosen at 90 degrees, a polarized monochromatic beam is produced. While synchrotron sources are naturally polarized, polarized beams have been less accessible for field and clinical applications. Development has begun of polarized beam sources using very low power x-ray tubes coupled to polycapillary optics. The choice of the polarizing and analyzing crystals is a tradeoff between intensity and sensitivity to depolarization effects. Intensity and rocking curve measurements have been performed with matched silicon crystals and graphite crystals.

Schmitz, Robert; Bingölbali, Ayhan; Hussain, Abrar; MacDonald, C. A.

2008-08-01

95

X-ray optics power considerations for high intensity x-ray free-electron lasers based on superconducting technology  

NASA Astrophysics Data System (ADS)

X-ray free-electron lasers generate ultrashort and very intense x-ray radiation in the wavelength domain reaching from the VUV (100 nm and shorter) all the way to the hard x-ray domain (typically 0.1 nm). FEL radiation features extreme brilliance, ultrashort pulse duration, and high peak power. Superconducting accelerators provide furthermore the possibility to accelerate a large number of electron bunches during a single radio-frequency pulse. Likewise the total number of x-ray pulses available for the experiments is increased leading to a significantly higher average brilliance. FEL light sources, and those based on super-conducting accelerator technology, are therefore considered to provide a new quality of short wavelength radiation if compared to existing x-ray sources. The high intensity and the high repetition rate lead to new requirements for x-ray optics in terms of peak and average power. Values for peak and average power are presented in relation to the proposed realization of the photon beamlines at the European XFEL facility.

Tschentscher, Th.; Sinn, H.; Tiedtke, K.; Wabnitz, H.

2007-05-01

96

Coherent Cone-Beam X-ray Microscopy  

SciTech Connect

A novel full-field imaging method using the (111) Bragg diffraction of a sub-micron gold crystal as the divergent cone-beam for sample illumination is reported. The divergence of the illumination allows for very high magnification, limited only by the achievable ratio of the crystal-to-sample and sample-to-detector distances. In this case an x-ray magnification of approximately 115 was achieved.

Harder, R.; Xiao, X. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2011-09-09

97

Comparison of polycapillary and curved crystal optics for convergent beam powder x-ray diffraction  

NASA Astrophysics Data System (ADS)

Comparisons were made of diffracted ring width, ring uniformity, system resolution and diffracted beam intensity for convergent beam powder diffraction using two different types of x-rays optics, doubly curved crystal optics^2 and polycapillary x-ray optics.^3,4 Measurements were made using very low power microfocus sources for small inorganic and organic standard samples. Detailed source and optics characterizations were performed to develop comparisons with theoretical calculations. Resolution and intensity were in good agreement with those obtained from simple geometrical calculations. ^2Z. W. Chen, N. Mail, F.Z. Wei, C. A. MacDonald, W. M. Gibson ``Total reflection x-ray fluorescence with low power sources coupled to doubly curved crystal optics,'' Spectrochimica. Acta. B, 60 (4), pp.471-8, 2005. ^3C.A. MacDonald and W.M. Gibson, ``Applications and Advances In Polycapillary Optics'', X-ray Spectrometry, 32 (3), 2003, pp 258-268. ^4C.A. MacDonald, S.M. Owens, and W.M. Gibson, ``Polycapillary X-Ray Optics for Microdiffraction,'' Journal of Applied Crystallography, 32, pp160-7, 1999.

Bingobali, Ayhan; Zhou, Wei; MacDonald, Carolyn

2006-03-01

98

Full spatial characterization of a nanofocused x-ray free-electron laser beam by ptychographic imaging  

PubMed Central

The emergence of hard X-ray free electron lasers (XFELs) enables new insights into many fields of science. These new sources provide short, highly intense, and coherent X-ray pulses. In a variety of scientific applications these pulses need to be strongly focused. In this article, we demonstrate focusing of hard X-ray FEL pulses to 125?nm using refractive x-ray optics. For a quantitative analysis of most experiments, the wave field or at least the intensity distribution illuminating the sample is needed. We report on the full characterization of a nanofocused XFEL beam by ptychographic imaging, giving access to the complex wave field in the nanofocus. From these data, we obtain the full caustic of the beam, identify the aberrations of the optic, and determine the wave field for individual pulses. This information is for example crucial for high-resolution imaging, creating matter in extreme conditions, and nonlinear x-ray optics.

Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Nilsson, Daniel; Uhlen, Fredrik; Vogt, Ulrich; Hertz, Hans M.; Schroer, Christian G.

2013-01-01

99

Full spatial characterization of a nanofocused x-ray free-electron laser beam by ptychographic imaging.  

PubMed

The emergence of hard X-ray free electron lasers (XFELs) enables new insights into many fields of science. These new sources provide short, highly intense, and coherent X-ray pulses. In a variety of scientific applications these pulses need to be strongly focused. In this article, we demonstrate focusing of hard X-ray FEL pulses to 125 nm using refractive x-ray optics. For a quantitative analysis of most experiments, the wave field or at least the intensity distribution illuminating the sample is needed. We report on the full characterization of a nanofocused XFEL beam by ptychographic imaging, giving access to the complex wave field in the nanofocus. From these data, we obtain the full caustic of the beam, identify the aberrations of the optic, and determine the wave field for individual pulses. This information is for example crucial for high-resolution imaging, creating matter in extreme conditions, and nonlinear x-ray optics. PMID:23567281

Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B; Nilsson, Daniel; Uhlén, Fredrik; Vogt, Ulrich; Hertz, Hans M; Schroer, Christian G

2013-01-01

100

Grazing incidence parametric X-ray radiation from the relativistic electron beam moving in parallel to the superlattice surface  

NASA Astrophysics Data System (ADS)

New configuration for generation of the parametric X-ray radiation (PXR) by an ultrarelativistic electron beam is considered. The beam propagates along the external surface of periodical multilayer structure (superlattice) while the photons are emitted under the condition of grazing incidence diffraction. PXR spectral intensity is calculated for this case. It is shown that this specific configuration of the electron beam and target radiator can be used for the PXR generation in a storage ring. It can allow one to obtain the monochromatic X-ray beams with the smoothly tuned frequency and the spectral intensity exceeding intensity of the synchrotron radiation in the narrow spectral ranges.

Feranchuk, I. D.; Feranchuk, S. I.

2007-05-01

101

Measurements of Fusion Reactions of Low-Intensity Radioactive Carbon Beams on C12 and their Implications for the Understanding of X-Ray Bursts  

NASA Astrophysics Data System (ADS)

The interaction between neutron-rich nuclei plays an important role for understanding the reaction mechanism of the fusion process as well as for the energy production through pycnonuclear reactions in the crust of neutron stars. We have performed the first measurements of the total fusion cross sections in the systems C10,14,15+C12 using a new active target-detector system. In the energy region accessible with existing radioactive beams, a good agreement between the experimental and theoretical cross sections is observed. This gives confidence in our ability to calculate fusion cross sections for systems which are outside the range of today's radioactive beam facilities.

Carnelli, P. F. F.; Almaraz-Calderon, S.; Rehm, K. E.; Albers, M.; Alcorta, M.; Bertone, P. F.; Digiovine, B.; Esbensen, H.; Niello, J. O. Fernández; Henderson, D.; Jiang, C. L.; Lai, J.; Marley, S. T.; Nusair, O.; Palchan-Hazan, T.; Pardo, R. C.; Paul, M.; Ugalde, C.

2014-05-01

102

Measurements of Fusion Reactions of Low-Intensity Radioactive Carbon Beams on ^{12}C and their Implications for the Understanding of X-Ray Bursts.  

PubMed

The interaction between neutron-rich nuclei plays an important role for understanding the reaction mechanism of the fusion process as well as for the energy production through pycnonuclear reactions in the crust of neutron stars. We have performed the first measurements of the total fusion cross sections in the systems ^{10,14,15}C+^{12}C using a new active target-detector system. In the energy region accessible with existing radioactive beams, a good agreement between the experimental and theoretical cross sections is observed. This gives confidence in our ability to calculate fusion cross sections for systems which are outside the range of today's radioactive beam facilities. PMID:24877935

Carnelli, P F F; Almaraz-Calderon, S; Rehm, K E; Albers, M; Alcorta, M; Bertone, P F; Digiovine, B; Esbensen, H; Niello, J O Fernández; Henderson, D; Jiang, C L; Lai, J; Marley, S T; Nusair, O; Palchan-Hazan, T; Pardo, R C; Paul, M; Ugalde, C

2014-05-16

103

X-ray pulse generation via laser Compton scattering using quasi-monoenergetic electron beam driven by laser acceleration  

NASA Astrophysics Data System (ADS)

We have demonstrated X-ray generation via laser Compton scattering using a laser-accelerated quasi-monoenergetic electron beam. X-rays were generated by scattering a femtosecond laser pulse (800 nm, 140 mJ, 100 fs) off a quasi-monoenergetic electron beam containing 70 pC electrons in the monoenergetic peak with an energy of 60 MeV produced by focusing an intense laser pulse (800 nm, 700 mJ, 40 fs) on a helium gas jet. A well-collimated X-ray beam with a divergence angle of approximately 5 mrad was generated. The number of X-ray photons was estimated to be 2x10^7 per pulse. The characteristics of X-rays were also investigated using simulation. The spectrum of X-rays emitted within the scattered angle of 5 mrad had a quasi-monochromatic structure with a peak at 60 keV. The number of X-ray photons was 1.8 x10^7, which was in a good agreement with the experimental result. The allowance delay range between the two laser pulses for X-ray generation was approximately 100 fs, and was nearly equal to the duration of the laser pulse scattered by the electron pulse. This suggests that the X-ray pulse duration was shorter than 100 fs.

Miura, Eisuke; Kuroda, Ryunosuke; Toyokawa, Hiroyuki

2012-10-01

104

Coherent convergent-beam time-resolved X-ray diffraction.  

PubMed

The use of coherent X-ray lasers for structural biology allows the use of nanometre diameter X-ray beams with large beam divergence. Their application to the structure analysis of protein nanocrystals and single particles raises new challenges and opportunities. We discuss the form of these coherent convergent-beam (CCB) hard X-ray diffraction patterns and their potential use for time-resolved crystallography, normally achieved by Laue (polychromatic) diffraction, for which the monochromatic laser radiation of a free-electron X-ray laser is unsuitable. We discuss the possibility of obtaining single-shot, angle-integrated rocking curves from CCB patterns, and the dependence of the resulting patterns on the focused beam coordinate when the beam diameter is larger or smaller than a nanocrystal, or smaller than one unit cell. We show how structure factor phase information is provided at overlapping interfering orders and how a common phase origin between different shots may be obtained. Their use in refinement of the phase-sensitive intensity between overlapping orders is suggested. PMID:24914153

Spence, John C H; Zatsepin, Nadia A; Li, Chufeng

2014-07-17

105

Cone-Beam X-Ray Tomography with Arbitrary-Orientation X-ray Tube  

Microsoft Academic Search

X-ray computed tomography is a technique to reconstruct an image of trans-axial slab of the object from a series of X-ray radiographs taken at a prior-known angle. Sequences of X-ray radiographs are served as two-dimensional projection data for a 3D tomography. The most popular Feldkamp algorithm which is based on filtered backprojection (FBP) approaches has shown to perform well for

D. Sueseenak; T. Chanwimalueang; W. Narkbuekaew; K. Chitsakul; C. Pintavirooj

2006-01-01

106

A new high-speed x-ray beam chopper.  

SciTech Connect

A new high-speed x-ray beam chopper using laser scanner technology has been developed and tested on the SRI-CAT sector 1 beamline at the Advanced Photon Source (APS) storage ring (1). As illustrated in figure 1, it is compact in size and has two sets of transmission windows: BK-7 glass for visible light transmission and 0.23-mm-thick Be for the transmission of x-rays. The rotor is made of aluminum and has a diameter of 50.8 mm. A 0.5-mm-wide and 2.29-mm-tall slit is cut through the center of the rotor. The circumference of the rotor has a coating of 1-mm-thick Ni, which gives an attenuation of 10{sup 8} at 30 keV. Turning at nearly 80000 RPM, this beam chopper has an opening time window of 2450 ns, corresponding to 67% of the revolution time of the APS storage ring. The primary feature in selecting laser scanner technology to develop into an x-ray beam chopper was the high level of rotational speed control of the rotor that makes up the beam chopper element (2). By using an optical feedback circuit to sample the rotational speed four times each revolution, the jitter in the position of the transmission open time window is only 3 ns at the 3 standard deviation level. The APS storage ring orbital frequency, supplied by the control room, is divided down to provide the appropriate drive frequency for the beam chopper motor controller. By this means, both the storage ring and the beam chopper are operating off the same master clock. After a turn-on time of about 15 to 20 seconds, the rotational precision of the motor results in immediate phase locking to the temporal structure of the APS storage ring. By inserting a Stanford delay generator between the frequency divider and the beam chopper motor controller, the phase between the storage ring temporal structure and the beam chopper rotation can be adjusted to position the transmission time window of the beam chopper on any desired part of the storage ring fill pattern. If an asymmetric fill pattern is used in the APS storage ring, as illustrated in figure 2, such that only one bucket falls within the transmission time window of the beam chopper, then time resolution as short as 100 ps becomes possible with this new compact beam chopper.

McPherson, A.; Wang, J.; Lee, P. L.; Mills, D. M.

1999-10-29

107

Calibration of Astro-D telescope with an x-ray pencil beam  

NASA Astrophysics Data System (ADS)

The x-ray optical properties of X-Ray Telescopes (XRTs) on board Asca were evaluated with an x-ray pencil beam at ISAS 30 m x-ray beam line. The total effective area of four XRTs is obtained to be about 1300 cm2, 800 cm2, and 450 cm2 at each energy of 1.5 keV, 4.5 keV, and 8.0 keV, respectively. These values are about 15% less than those calculated by ray tracing method in an ideal case. The shadow effect of closely packed foils might be the main reason for the degradation of effective area. The Point Spread Function of XRT was also measured by an x-ray CCD. We have also measured the contamination of stray light, which were caused by the one time reflected photons (by primary or secondary mirror) and photons reflected on the back side surface of the mirror shells. The stray light profile and intensity were consistent to the results simulated by the ray tracing.

Tsusaka, Yoshiyuki; Suzuki, Hisanori; Awaki, Hisamitsu; Yamashita, Koujun; Kunieda, Hideyo; Tawara, Yuzuru; Ogasaka, Yasushi; Uchibori, Yasuhiro; Honda, Hirohiko; Itoh, Masayuki; Tsunemi, Hiroshi; Hayashida, Kiyoshi; Nomoto, Susumu; Wada, Mikio; Miyata, Emi; Serlemitsos, Peter J.; Jalota, Lalit; Soong, Yang

1994-02-01

108

Conceptual design study of an intense x-ray source for coronary angiography  

SciTech Connect

Calculations are presented for several 1.4 GeV electron storage ring designs which, with an ultra-high field (80 kG) superconducting wiggler magnet and beam current I = 400 mA, will generate a 33.16 keV x-ray beam at 20 m from the wiggler of adequate intensity (6 10{sup 9}/mm{sup {minus}2} sec{sup {minus}1}) and areal size for iodine K-edge coronary dichromography in humans.

Blumberg, L.N.

1992-03-01

109

Tolerance of Arteries to Microplanar X-Ray Beams  

SciTech Connect

Purpose: The purpose is to evaluate effects of a new radiotherapy protocol, microbeam radiation therapy, on the artery wall. In previous studies on animal models, it was shown that capillaries recover well from hectogray doses of X-rays delivered in arrays of narrow ({<=}50 {mu}m) beams with a minimum spacing of 200 {mu}m. Here, short- and long-term effects of comparable microplanar beam configurations on the saphenous artery of the mouse hind leg were analyzed in situ by use of nonlinear optics and compared with histopathologic findings. Methods and Materials: The left hind leg of normal mice including the saphenous artery was irradiated by an array of 26 microbeams of synchrotron X-rays (50 {mu}m wide, spaced 400 {mu}m on center) with peak entrance doses of 312 Gy and 2,000 Gy. Results: The artery remained patent, but narrow arterial smooth muscle cell layer segments that were in the microplanar beam paths became atrophic and fibrotic in a dose-dependent pattern. The wide tunica media segments between those paths hypertrophied, as observed in situ by two-photon microscopy and histopathologically. Conclusions: Clinical risks of long-delayed disruption or occlusion of nontargeted arteries from microbeam radiation therapy will prove less than corresponding risks from broad-beam radiosurgery, especially if peak doses are kept below 3 hectograys.

Sanden, Boudewijn van der, E-mail: Boudewijn.vandersanden@ujf-grenoble.f [INSERM U836, Institute of Neuroscience Grenoble (France); Braeuer-Krisch, Elke [European Synchrotron Radiation Facility, Grenoble (France); Siegbahn, Erik Albert [Department of Oncology and Pathology, Karolinska Institutet, Stockholm (Sweden); Ricard, Clement [INSERM U836, Institute of Neuroscience Grenoble (France); Vial, Jean-Claude [CNRS UMR 5588, Physical Spectroscopy, Grenoble (France); Laissue, Jean [Institute of Pathology, University of Bern (Switzerland)

2010-08-01

110

Using E-Beam and X-Ray Lithography Techniques to Fabricate Zone Plates for Hard X-ray  

NASA Astrophysics Data System (ADS)

A high-resolution zone plate for focusing and magnifying hard-x-rays require very high fabrication precision and high aspect ratio metal structures and therefore post perhaps the most challenging task to the nanofabrication. We present a nanofabrication strategy to fabricate such devices for x-ray applications which takes advantage of the state-of-the-art x-ray lithography and electroplating processes. The substrate used to fabricate the x-ray mask is first prepared by depositing Si3N4 film on a Si wafer. Electron beam lithography capable of writing small lines (<10nm on photoresist) is then used to create desired zone plate pattern. An Au layer is electrodeposited into nano-paterned photoresist structure of sufficient thickness and the resist is then removed to expose the Au zone plate structure. Finally, the KOH is used to etch the Si wafer down to the Si3N4 film and to produce the desired x-ray hard mask. This hard mask defines the zone plate pattern with the x-ray lithography method. We demonstrate that the mask prepared by this method is of very high precision-30nm outermost zone-can be obtained. X-ray lithography process is attempted with convincing results.

Lo, T. N.; Chen, Y. T.; Liu, C. J.; Chang, W. D.; Lai, T. Y.; Wu, H. J.; Lin, I. K.; Su, C. I.; Shew, B. Y.; Je, J. H.; Margaritondo, G.; Hwu, Y.

2007-01-01

111

Countermeasures for X-ray Intensity Fluctuation on BL11XU at SPring-8  

SciTech Connect

This paper reports that the countermeasures against X-ray intensity fluctuation have been developed on BL11XU at SPring-8. Observed X-ray intensity fluctuation might be caused from mechanical vibrations of monochromator crystals. So, we measured the vibrations under various conditions to identify vibration sources and took countermeasures against the mechanical vibrations. As a result, the methods successfully removed the mechanical vibrations and the X-ray intensity fluctuation was reduced to about half.

Kiriyama, K.; Shobu, T. [Japan Atomic Energy Agency, Koto 1-1-1, Sayo-cho, Sayo-gun 679-5148 (Japan); SPring-8 service Co., Ltd., Koto 2-23-1, Kamigori-cho, Ako-gun 678-1205 (Japan); Shiwaku, H. [Japan Atomic Energy Agency, Koto 1-1-1, Sayo-cho, Sayo-gun 679-5148 (Japan); Mochizuki, T. [Japan Synchrotron Radiation Research Institute, Koto 1-1-1, Sayo-cho, Sayo-gun 679-5148 (Japan); Tozawa, K. [Ishikawajima-Harima Heavy Industries Co., Ltd., Shin-Nakahara-cho 1, Isogo-ku, Yokohama 235-8501 (Japan)

2007-01-19

112

Water equivalence of micelle gels for x-ray beams  

NASA Astrophysics Data System (ADS)

Micelle gel is a radiochromic hydrogel with the potential to be used as a three dimensional (3D) radiation dosimeter. Since an ideal dosimeter should present water equivalent properties, in this study the water equivalence of two formulations of micelle gel has been investigated by calculating electron density, effective atomic number, fractional interaction probabilities, mass attenuation coefficient. The depth doses for kilovoltage and megavoltage x-ray beams have also modelled using Monte Carlo code. Based on the results of this work, micelle gels can be considered as water equivalent dosimeters.

Gorjiara, T.; Hill, R.; Kuncic, Z.; Bosi, S.; Baldock, C.

2013-06-01

113

Study of dosimetry consistency for kilovoltage x-ray beams.  

PubMed

In this paper, the consistency of kilovoltage (tube potentials between 40 and 300 kV) x-ray beam dosimetry using the "in-air" method and the in-phantom measurement has been studied. The procedures for the measurement of the central-axis depth-dose curve, which serve as a link between the dose at the reference depth to the dose elsewhere in a phantom, were examined. The uncertainties on the measured dose distributions were analyzed with the emphasis on the surface dose measurement. The Monte Carlo method was used to calculate the perturbation correction factors for a photon diode and a NACP plane-parallel ionization chamber at different depths in a water phantom irradiated by 100-300 kV (2.43 mm Al-3.67 mm Cu half-value layer) x-ray beams. The depth-dose curves measured with these two detectors, after correcting for the perturbation effect (up to 15% corrections), agreed with each other to within 1.5%. Comparisons of the doses at the phantom surface and at 2 cm depth in water for photon beams of 100-300 kV tube potential obtained using the "backscatter" method and those using the "in-phantom" measurement have shown that the "in-air" method can be equally applied to this energy range if the depth-dose curve can be measured accurately. To this end, measured depth ionization curves require depth-dependent correction factors. PMID:9874830

Ma, C M; Li, X A; Seuntjens, J P

1998-12-01

114

Hard X-ray Imaging Microscopy using X-ray Guide Tube as Beam Condenser for Field Illumination  

NASA Astrophysics Data System (ADS)

An optical system for illumination of object in x-ray imaging microscopy is developed. The optical system is a beam condenser consisting of a single-bounce conical-shape mono-capillary (x-ray guide tube: XGT) made of Pyrex glass. The XGT condenser was tested at the beam line 47XU of SPring-8 using a Fresnel zone plate as an objective lens. Comparing with the microscope without beam condenser, the flux density is improved by a factor of 12-20 in the x-ray energy range of 6-8 keV. Test patterns with a 50 nm-structure are clearly resolved at 8 keV with an exposure time less than 1 s.

Suzuki, Yoshio; Takeuchi, Akihisa; Uesugi, Kentaro; Terada, Yasuko; Nakazawa, Hiromoto; Ohzawa, Sumito; Aoyama, Tomoki; Nii, Hajime; Handa, Katsumi

2013-10-01

115

An experimental measurement of metal multilayer x-ray reflectivity degradation due to intense x-ray flux  

SciTech Connect

The degradation of the x-ray reflection characteristics of metal multilayer Bragg diffractors due to intense x-ray flux was investigated. The Z-pinch plasma produced by PROTO II of Sandia National Laboratories, Albuquerque, New Mexico, was used as the source. The plasma generated total x-ray yields of as much as 40 kJ with up to 15 kJ in the neon hydrogen- and helium-like resonance lines in nominal 20-ns pulses. Molybdenum-carbon, palladium-carbon, and tungsten-carbon metal multilayers were placed at 15 and 150 cm from the plasma center. The multilayers were at nominal angles of 5/sup 0/ and 10/sup 0/ to diffract the neon resonance lines. The time-integrated x-ray reflection of the metal multilayers was monitored by x-ray film. A fluorescer-fiber optic-visible streak camera detector system was then used to monitor the time-resolved x-ray reflection characteristics of 135 A- 2d tungsten-carbon multilayers. A large specular component in the reflectivity prevented determination of the rocking curve of the multilayer. For a neon implosion onto a vanadium-doped polyacrylic acid foam target shot, detailed modeling was attempted. The spectral flux was determined with data from 5 XRD channels and deconvolved using the code SHAZAM. The observed decay in reflectivity was assumed to correspond to the melting of the first tungsten layer. A ''conduction factor'' of 82 was required to manipulate the heat loading of the first tungsten layer such that the time of melting corresponded to the observed decay. The power at destruction was 141 MW/cm/sup 2/ and the integrated energy at destruction was 2.0 J/cm/sup 2/. 82 refs., 66 figs., 10 tabs.

Hockaday, M.Y.P.

1987-06-01

116

Intensity-Modulated Advanced X-ray Source (IMAXS) for Homeland Security Applications  

Microsoft Academic Search

X-ray cargo inspection systems for the detection and verification of threats and contraband require high x-ray energy and high x-ray intensity to penetrate dense cargo. On the other hand, low intensity is desirable to minimize the radiation footprint. A collaboration between HESCO?PTSE Inc., Schonberg Research Corporation and Rapiscan Laboratories, Inc. has been formed in order to design and build an

Willem G. J. Langeveld; William A. Johnson; Roger D. Owen; Russell G. Schonberg

2009-01-01

117

Intensity-Modulated Advanced X-ray Source (IMAXS) for Homeland Security Applications  

Microsoft Academic Search

X-ray cargo inspection systems for the detection and verification of threats and contraband require high x-ray energy and high x-ray intensity to penetrate dense cargo. On the other hand, low intensity is desirable to minimize the radiation footprint. A collaboration between HESCO\\/PTSE Inc., Schonberg Research Corporation and Rapiscan Laboratories, Inc. has been formed in order to design and build an

Willem G. J. Langeveld; William A. Johnson; Roger D. Owen; Russell G. Schonberg

2009-01-01

118

Intense ultrashort-pulse laser-solid interactions for soft x-ray generation  

Microsoft Academic Search

Short-pulse high-intensity laser-plasma interactions are investigated numerically with a fluid code and experimentally with optical and x-ray diagnostics. The emitted x-ray spectrum is characterized in the vicinity of the water window for laser intensities of 4 X 1017 W\\/cm2 and pulsewidths of 400 fs. Optimization of the x-ray pulsewidth using these results is also discussed.

Donald P. Umstadter; X. Liu; Jonathan Workman

1993-01-01

119

Food Irradiation Using Electron Beams and X-Rays  

NASA Astrophysics Data System (ADS)

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include insect disinfestation, sprouting inhibition, delayed ripening, and the enhanced safety and sterilization of fresh and frozen meat products, seafood, and eggs. With special regard to food safety, bacteria such as Salmonella enteridis, Listeria monocytogenes, Campylobacter jejuni and Escherichia coli serotype O157:H7 are the primary causes of food poisoning in industrialized countries. Ionizing doses in the range of only 1-5 kilogray (kGy) can virtually eliminate these organisms from food, without affecting the food's sensory and nutritional qualities, and without inducing radioactivity. The key elements of an accelerator-based irradiation facility include the accelerator system, a scanning system, and a material handling system that moves the product through the beam in a precisely controlled manner. Extensive radiation shielding is necessary to reduce the external dose to acceptable levels, and a safety system is necessary to prevent accidental exposure of personnel during accelerator operation. Parameters that affect the dose distribution must be continuously monitored and controlled with process control software. The choice of electron beam vs x-ray depends on the areal density (density times thickness) of the product and the anticipated mass throughput. To eliminate nuclear activation concerns, the maximum kinetic energy of the accelerator is limited by regulation to 10 MeV for electron beams, and 5 MeV for x-rays. From penetration considerations, the largest areal density that can be treated by double-sided electron irradiation at 10 MeV is about 8.8 g/cm2. Products having greater areal densities must be processed using more penetrating x-rays. The mass throughput (dM/dt in kg/s) of an accelerator-based system is proportional to the average beam power (P in kW), and inversely proportional to the minimum required dose (Dm in kGy, with 1 kGy = 1 kJ/kg). The constant of proportionality is the mass throughput efficiency. Throughput efficiencies of 0.4 or better are typical of electron beam installations, but are only 0.025-0.035 for x-ray installations, primarily because of the inefficiency of bremsstrahlung generation at 5 MeV (about 8an axially-coupled, standing-wave, L-band linac with an average power in excess of 100 kW to achieve reasonable throughput rates with x-ray processing. Various design aspects of this new machine will be presented.

Miller, Bruce

2003-04-01

120

High intensity compact Compton X-ray sources: Challenges and potential of applications  

NASA Astrophysics Data System (ADS)

Thanks to the exceptional development of high power femtosecond lasers in the last 15 years, Compton based X-ray sources are in full development over the world in the recent years. Compact Compton sources are able to combine the compactness of the instrument with a beam of high intensity, high quality, tunable in energy. In various fields of applications such as biomedical science, cultural heritage preservation and material science researches, these sources should provide an easy working environment and the methods currently used at synchrotrons could be largely developed in a lab-size environment as hospitals, labs, or museums.

Jacquet, M.

2014-07-01

121

Phase Retrieval from X-Ray Intensity Measurements  

NASA Astrophysics Data System (ADS)

This thesis consists of a series of theoretical contributions to algorithmic methods for phase retrieval from diffraction intensity measurements. Our work is presented in three related, but somewhat independent parts. The first part consists of a refinement to the phase propagation methods developed by Bates et al. in 1982 [1--3]. We introduce a correction term for the calculation of the phase difference between actual samples in reciprocal space. We show, numerically, how our method leads to improved image reconstructions in 1D. In the second part we develop an algorithm for phase retrieval based on the Fourier series expansion of a sharp, square object support. We obtain a series of equations that describe the dependence between different points in reciprocal space, and show that this dependence becomes simpler when only a few terms of the expansion are taken into account. Our algorithm consists of two stages: In the first one, a few of the coupled equations are solved in order to obtain the phase within a localized region. This is followed by a propagation stage in which the rest of the unknown phase values are obtained by means of simple propagation method. We present a numerical example in which we use a downhill minimization method to solve the equations that arise on the first stage. Finally, we propose a strategy for phase retrieval from x-ray diffraction measurements of a system undergoing the kinetics of a first-order transition following a temperature quench. We use both, a simple theoretical model and numerical simulations to obtain an expression for the average phase-decorrelation time in ordering dynamics. We present an example to show how this result can be used to solve the phase problem faster and with higher convergence rates.

Montiel, David

122

Monte Carlo simulator of realistic x-ray beam for diagnostic applications  

SciTech Connect

Purpose: Monte Carlo simulation is a very useful tool for radiotherapy and diagnostic radiology. Yet even with the latest PCs, simulation of photon spectra emitted by an x-ray tube is a time-consuming task, potentially reducing the possibility to obtain relevant data such as dose evaluations, simulation of geometric settings, or monitor detector efficiency. This study developed and validated a method to generate random numbers for realistic beams in terms of photon spectrum and intensity to simulate x-ray tubes via Monte Carlo algorithms. Methods: Starting from literature data, the most common semiempirical models of bremsstrahlung are analyzed and implemented, adjusting their formulation to describe a large irradiation area (i.e., large field of view) and to take account of the heel effect as in common practice during patient examinations. Results: Simulation results show that Birch and Marshall's model is the fastest and most accurate for the aims of this work. Correction of the geometric size of the beam and validation of the intensity variation (heel effect) yielded excellent results with differences between experimental and simulated data of less than 6%. Conclusions: The results of validation and execution time showed that the tube simulator calculates the x-ray photons quickly and efficiently and is perfectly capable of considering all the phenomena occurring in a real beam (total filtration, focal spot size, and heel effect), so it can be used in a wide range of applications such as industry, medical physics, or quality assurance.

Bontempi, Marco; Andreani, Lucia; Rossi, Pier Luca; Visani, Andrea [Biomechanics Laboratory, Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna (Italy); Department of Physics, University of Bologna, viale Berti Pichat 6/2, 40137 Bologna (Italy); Biomechanics Laboratory, Istituto Ortopedico Rizzoli, via di Barbiano 1/10, 40136 Bologna (Italy)

2010-08-15

123

A Bragg beam splitter for hard x-ray free-electron lasers.  

PubMed

We report a Bragg beam splitter developed for utilization of hard x-ray free-electron lasers. The splitter is based on an ultrathin silicon crystal operating in the symmetric Bragg geometry to provide high reflectivity and transmissivity simultaneously. We fabricated frame-shaped Si(511) and (110) crystals with thicknesses below 10 ?m by a reactive dry etching method using atmospheric-pressure plasma. The thickness variation over an illuminated area is less than 300 nm peak-to-valley. High crystalline perfection was verified by topographic and diffractometric measurements. The crystal thickness was evaluated from the period of the Pendellösung beats measured with a highly monochromatic and collimated x-ray probe. The crystals provide two replica pulses with uniform wavefront [(<1/50)?] and low spatial intensity variation (<5%). These Bragg beam splitters will play an important role in innovating XFEL applications. PMID:23481739

Osaka, Taito; Yabashi, Makina; Sano, Yasuhisa; Tono, Kensuke; Inubushi, Yuichi; Sato, Takahiro; Matsuyama, Satoshi; Ishikawa, Tetsuya; Yamauchi, Kazuto

2013-02-11

124

Unveiling and Driving Hidden Resonances with High-Fluence, High-Intensity X-Ray Pulses  

SciTech Connect

We show that high fluence, high-intensity x-ray pulses from the world's first hard x-ray free-electron laser produce nonlinear phenomena that differ dramatically from the linear x-ray-matter interaction processes that are encountered at synchrotron x-ray sources. We use intense x-ray pulses of sub-10-fs duration to first reveal and subsequently drive the 1s{r_reversible}2p resonance in singly ionized neon. This photon-driven cycling of an inner-shell electron modifies the Auger decay process, as evidenced by line shape modification. Our work demonstrates the propensity of high-fluence, femtosecond x-ray pulses to alter the target within a single pulse, i.e., to unveil hidden resonances, by cracking open inner shells energetically inaccessible via single-photon absorption, and to consequently trigger damaging electron cascades at unexpectedly low photon energies.

Kanter, E. P.; Kraessig, B.; Li, Y.; March, A. M.; Ho, P.; Southworth, S. H.; Young, L. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Rohringer, N. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Max Planck Institute for the Physics of Complex Systems, 01187 Dresden (Germany); Max Planck Advanced Study Group, Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); Santra, R. [Argonne National Laboratory, Argonne, Illinois 60439 (United States); Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg (Germany); Department of Physics, University of Hamburg, Jungiusstrasse 9, 20355 Hamburg (Germany); Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106 (United States); DiMauro, L. F.; Doumy, G.; Roedig, C. A. [Ohio State University, Columbus, Ohio 43210 (United States); Berrah, N.; Fang, L.; Hoener, M. [Western Michigan University, Kalamazoo, Michigan 49008 (United States); Bucksbaum, P. H.; Ghimire, S.; Reis, D. A. [PULSE Center, SLAC, Menlo Park, California 94025 (United States); Bozek, J. D.; Bostedt, C. [Linac Coherent Light Source, SLAC, Menlo Park, California 94025 (United States)

2011-12-02

125

Intensity oscillations and heating of the coronal X-ray bright points from Hinode\\/XRT  

Microsoft Academic Search

Aims: Our aim is to investigate the intensity oscillations in coronal X-ray Bright Points (XBPs). Methods: We analysed a 7 h long time sequence of the soft X-ray images obtained on April 14, 2007 with a 2 min cadence using the X-Ray Telescope (XRT) on-board the Hinode mission. We use SSW in IDL to derive the time series of 14

R. Kariyappa; B. A. Varghese

2008-01-01

126

Inductive energy technology for pulsed intense X-ray sources  

Microsoft Academic Search

Defense Special Weapons Agency (DSWA) has been developing inductive energy storage technology (IES) for applications requiring short pulses of X-rays with peak radiation power in the terawatt range. The purpose of this program is to develop more compact and affordable pulsed power sources and power flow technology needed for efficient conversion of the electromagnetic energy into radiation. Performance characteristics of

Kenneth D. Ware; Paul G. Filios; Richard L. Gullickson; James E. Rowley; Ralph F. Schneider; William J. Summa; Ihor M. Vitkovitsky

1997-01-01

127

Divergence measurements of soft x-ray laser beam  

SciTech Connect

The divergence of the CVI 182 A lasing line generated in a rapidly recombining, magnetically confined plasma column was measured using soft x-ray spectrometers equipped with multichannel detectors. In addition to measurements of the relative divergence, an absolute divergence of approx.9 mrad at a magnetic field of 20 kG and approx.5 mrad at a magnetic field of 35 or 50 kG was obtained by a direct scan of the 182 A axial radiation. Based on this data a peak 182 A intensity of approx.100 kW is obtained. Calculations of the spatial distribution of gain in the plasma were in very good agreement with the experimental data.

Suckewer, S.; Skinner, C.H.; Kim, D.; Valeo, E.; Voorhees, D.; Wouters, A.

1986-07-01

128

Z pinches as intense x-ray sources for inertial confinement fusion applications  

SciTech Connect

Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x-rays. On the Saturn pulsed-power accelerator at Sandia National Laboratories, currents of 6 to 8 MA with a risetime of less than 50 ns have been used to drive cylindrically-symmetric arrays of wires, producing x-ray energies greater than 400 kJ with x-ray pulsewidths less than 5 ns and peak x-ray powers of 75 {+-} 10 TW. Using similar loads, PBFA Z has produced > 1.5 MJ and > 150 TW of x-rays in the first four months of operation in the z-pinch mode. These x-ray energies and powers are records for laboratory x-ray production. The x-ray output can be thermalized into a near-Planckian x-ray source by containing it within a cylindrical radiation case (a hohlraum). These energetic, intense, large volume, long-lived hohlraum x-ray sources have recently been used for ICF-relevant ablator physics experiments and offer the potential for performing many new basic physics and fusion-relevant experiments.

Matzen, M.K.

1997-05-01

129

Propagation of an X-ray beam modified by a photonic crystal.  

PubMed

A method of calculating the transmission of hard X-ray radiation through a perfect and well oriented photonic crystal and the propagation of the X-ray beam modified by a photonic crystal in free space is developed. The method is based on the approximate solution of the paraxial equation at short distances, from which the recurrent formula for X-ray propagation at longer distances is derived. A computer program for numerical simulation of images of photonic crystals at distances just beyond the crystal up to several millimetres was created. Calculations were performed for Ni inverted photonic crystals with the [111] axis of the face-centred-cubic structure for distances up to 0.4?mm with a step size of 4?µm. Since the transverse periods of the X-ray wave modulation are of several hundred nanometres, the intensity distribution of such a wave is changed significantly over the distance of several micrometres. This effect is investigated for the first time. PMID:24971967

Kohn, V G; Snigireva, I; Snigirev, A

2014-07-01

130

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

NASA Technical Reports Server (NTRS)

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

Edwards, David L.

1999-01-01

131

Characterization of the 46.9-nm soft X-ray laser beam from a capillary discharge  

NASA Astrophysics Data System (ADS)

Intense lasing had been obtained from argon plasma in the soft X-ray region from a capillary discharge plasma system. Different diagnostics have been used to characterize the lasing properties by recording the temporal, spatial, and spectral profiles of the emission. The divergence measurement indicates that the soft X-ray laser beam has good directionality with a divergence of 3.5 mrad. The spectrum of the laser beam measured using a transmission grating showed intense lasing line at 46.9 nm. Diffraction orders as high as 10th orders were observed. The temporal profile recorded with a vacuum diode showed a distinct laser peak with a pulse width ~1.2 ns (FWHM). In addition, the coherence of the X-ray laser beam was also confirmed from the high-contrast interference fringes (visibility ~85 %) recorded using double slits.

Barnwal, S.; Prasad, Y. B. S. R.; Nigam, S.; Aneesh, K.; Sharma, M. L.; Kushwaha, R. P.; Tripathi, P. K.; Naik, P. A.; Chakera, J. A.; Navathe, C. P.; Gupta, P. D.

2014-04-01

132

Efficient Monte Carlo simulations in kilovoltage x-ray beams  

NASA Astrophysics Data System (ADS)

Kilovoltage x-ray systems are modeled with BEAMnrc using directional bremsstrahlung splitting, which is five to six orders of magnitude more efficient than a simulation without splitting and 60 times more efficient than uniform bremsstrahlung splitting. Optimum splitting numbers are between 2 and 3 orders of magnitude larger than for megavoltage beams A self-consistent approach for the calculation of free-air chamber correction factors with the EGSnrc Monte Carlo system is introduced. In addition to the traditional factors employed to correct for attenuation (A att), photon scatter (Ascat) and electron energy loss (Aeloss), correction factors for aperture leakage (Aap) and backscatter (A b) are defined. Excellent agreement is obtained between calculated and measured Ascat and Aeloss values. Computed Aatt values for medium-energy and mammography beams reproduce the measurements well. For low-energy lightly-filtered beams, Aatt values show significant differences with the experiment. Scaling the tungsten L-shell EII cross-sections by a factor of 2 eliminate these differences. The inconsistency of the evacuated-tube technique for measuring Aatt is negligible for medium-energy and mammography beams, and 0.2% for low-energy lightly-filtered beams The aperture correction Aap becomes significant in the medium-energy range with increasing energy. The newly introduced backscatter correction Ab becomes as high as 0.4% in the low-energy range. In the medium-energy range, calculations reproduce experimental half-value layer values to better than 2.3%. For mammography beams a difference of 0.5% and 2.5% with experiment is obtained with and without a scaling of the tungsten L-shell EII cross-sections respectively. For low-energy lightly-filtered beams a scaling factor of 2.1 gives the best agreement (˜ 3%) with the experiment, significantly worsening to 8% for a scaling factor of 1.8, which gives the best match for Aatt. The fast algorithm for calculating the scatter contribution to cone beam computed tomography scans increases the efficiency by more than 3 orders of magnitude. Smoothing the scatter distribution pushes the efficiency gain over four orders of magnitude. The iterative correction algorithm removes the scatter from the measured scans improving the accuracy of the reconstructed image. The dependence of image reconstruction accuracy on the sophistication of the photon interaction models is investigated. No significant difference is observed when using models including coherent and incoherent scattering. Considering only incoherent scattering for free electrons shows a significant bias.

Mainegra-Hing, Ernesto

133

Coherent x-ray transition and diffraction radiation of microbunched beams  

NASA Astrophysics Data System (ADS)

Theoretical and numerical results on angular and spectral distributions and total number of photons of several types of coherent radiation produced by microbunched beams passing through radiators are presented: coherent x-ray bremsstrahlung, x-ray transition, resonance transition, and diffraction radiations. The possibility of observation and application of these new types of radiation for the study of parameters of electron beam microbunching, which is important for the effectiveness of x-ray free electron lasers, is discussed.

Ispirian, K. A.; Ispiryan, M.

2013-02-01

134

Silicon Mirrors for High-Intensity X-Ray Pump and Probe Experiments  

NASA Astrophysics Data System (ADS)

An all-x-ray pump and probe capability is highly desired for the free-electron laser community. A possible implementation involves the use of an x-ray mirror downstream of the sample to backreflect the pump beam onto itself. We expose silicon single crystals, a candidate for this hard-x-ray mirror, to the hard-x-ray beam of the Linac Coherent Light Source (SLAC National Acceleration Laboratory) to assess its suitability. We find that silicon is an appropriate mirror material, but its reflectivity at high x-ray fluences is somewhat unpredictable. We attribute this behavior to x-ray-induced local damage in the mirror, which we have characterized post mortem via microdiffraction, scanning electron microscopy, and Raman spectroscopy. We demonstrate a strategy to reduce local damage by using a structured silicon-based mirror. Preliminary results suggest that the latter yields reproducible Bragg reflectivity at high x-ray fluences, promising a path forward for silicon single crystals as x-ray backreflectors.

Pardini, Tom; Boutet, Sébastien; Bradley, Joseph; Döppner, Tilo; Fletcher, Luke B.; Gardner, Dennis F.; Hill, Randy M.; Hunter, Mark S.; Krzywinski, Jacek; Messerschmidt, Marc; Pak, Arthur E.; Quirin, Florian; Sokolowski-Tinten, Klaus; Williams, Garth J.; Hau-Riege, Stefan P.

2014-05-01

135

X-ray generation via laser Compton scattering using quasi-monoenergetic electron beam driven by laser-plasma acceleration  

NASA Astrophysics Data System (ADS)

The first demonstration of X-rays generated via laser Compton scattering using a quasi-monoenergetic electron beam with a narrow energy spread driven by laser-plasma acceleration is reported. X-rays are produced by scattering a femtosecond laser pulse (800 nm, 140 mJ, 100 fs) off a quasi-monoenergetic electron beam containing 70 pC electrons in the monoenergetic peak with an energy of 60 MeV produced by focusing an intense laser pulse (800 nm, 700 mJ, 40 fs) on a helium gas jet. A well-collimated X-ray beam with a divergence angle of approximately 5 mrad is produced. The number of X-ray photons is estimated to be 2×107 per pulse. Numerical simulation results show that the spectrum of the X-rays within the scattered angle of 5 mrad is the quasi-monochromatic distribution with a peak at 60 keV, and the photon number is 1.8×107. The X-ray photon number is in a good agreement with the experimental result.

Miura, Eisuke; Ishii, Satoshi; Tanaka, Kenji; Kashiwaya, Shun; Kuroda, Ryunosuke; Toyokawa, Hiroyuki

2012-12-01

136

X-Ray Radiation Measurements With Photodiodes In Plasmas Generated By 1017 W/Cm2 Intensity Krf Excimer Laser Pulses  

NASA Astrophysics Data System (ADS)

Experiments were carried out using a prepulse-free hybrid KrF excimer-dye laser system (700fs pulse duration, 248nm wavelength, 15mJ pulse energy). The intensity of the p-polarized, focused laser beam was 1.5.1017 W/cm2. Vacuum ultraviolet (VUV) and x-rays from solid state laser plasmas were generated in the laser-plasma interaction of subpicosecond laser pulses of nonrelativistic laser intensities. An x-ray sensitive FLM photodiode (ITE, Warsaw) was used to detect x-rays between 1-19 keV in front of the targets. The diode was filtered by a 4?m Al foil. The dependence of the x-ray flux on laser intensity and the angular distribution of x-rays for aluminum and copper targets in the half space of the front side of the targets were investigated.

Rácz, E.; Földes, I. B.; Ry?, L.

2006-01-01

137

Thirty-Meter X-Ray Pencil Beam Line at the Institute of Space and Astronautical Science  

Microsoft Academic Search

A 30-m-long X-ray beam line has been built at the Institute of Space and Astronautical Science (ISAS) to evaluate the performance of X-ray optical instruments for space programs, in particular for the X-ray telescope onboard the Astro-D (Asca) satellite. This beam line consists of an X-ray generator, a 30-m-long vacuum duct, and measuring chambers. Strong and stable X-ray pencil beams

Hideyo Kunieda; Yoshiyuki Tsusaka; Hisanori Suzuki; Yasushi Ogasaka; Hisamitsu Awaki; Yuzuru Tawara; Koujun Yamashita; Takashi Yamazaki; Masayuki Itoh; Tsuneo Kii; Fumiyoshi Makino; Yoshiaki Ogawara; Hiroshi Tsunemi; Kiyoshi Hayashida; Susumu Nomoto; Mikio Wada; Emi Miyata; Isamu Hatsukade

1993-01-01

138

X-ray acoustic computed tomography with pulsed x-ray beam from a medical linear accelerator  

PubMed Central

Purpose: The feasibility of medical imaging using a medical linear accelerator to generate acoustic waves is investigated. This modality, x-ray acoustic computed tomography (XACT), has the potential to enable deeper tissue penetration in tissue than photoacoustic tomography via laser excitation. Methods: Short pulsed (?s-range) 10 MV x-ray beams with dose-rate of approximately 30 Gy/min were generated from a medical linear accelerator. The acoustic signals were collected with an ultrasound transducer (500 KHz central frequency) positioned around an object. The transducer, driven by a computer-controlled step motor to scan around the object, detected the resulting acoustic signals in the imaging plane at each scanning position. A pulse preamplifier, with a bandwidth of 20 KHz–2 MHz at ?3 dB, and switchable gains of 40 and 60 dB, received the signals from the transducer and delivered the amplified signals to a secondary amplifier. The secondary amplifier had bandwidth of 20 KHz–30 MHz at ?3 dB, and a gain range of 10–60 dB. Signals were recorded and averaged 128 times by an oscilloscope. A sampling rate of 100 MHz was used to record 2500 data points at each view angle. One set of data incorporated 200 positions as the receiver moved 360°. The x-ray generated acoustic image was then reconstructed with the filtered back projection algorithm. Results: The x-ray generated acoustic signals were detected from a lead rod embedded in a chicken breast tissue. The authors found that the acoustic signal was proportional to the x-ray dose deposition, with a correlation of 0.998. The two-dimensional XACT images of the lead rod embedded in chicken breast tissue were found to be in good agreement with the shape of the object. Conclusions: The first x-ray acoustic computed tomography image is presented. The new modality may be useful for a number of applications, such as providing the location of a fiducial, or monitoring x-ray dose distribution during radiation therapy. Although much work is needed to improve the image quality of XACT and to explore its performance in other irradiation energies, the benefits of this modality, as highlighted in this work, encourage further study.

Xiang, Liangzhong; Han, Bin; Carpenter, Colin; Pratx, Guillem; Kuang, Yu; Xing, Lei

2013-01-01

139

Improvement of Image Quality in Transmission Computed Tomography Using Synchrotron Monochromatic X-Ray Sheet Beam.  

National Technical Information Service (NTIS)

In the transmission CT imaging system with scintillator-CCD detector using synchrotron monochromatic x-ray as sheet beam, improvement of reconstructed image quality is investigated, The properties of experimental facilities cause the incident beam intensi...

T. Yuasa T. Takeda T. Zeniya Y. Hasegawa K. Hyodo

2001-01-01

140

Buildup of X-ray laser gain by fluctuations in channeled relativistic beam systems  

NASA Astrophysics Data System (ADS)

A theory for the buildup of stimulated X-ray radiation from spontaneous emission in relativistic channeling beam systems is presented. Explicit expressions for the startup operator for amplification is obtained from a first-principles quantum Hamiltonian including channel fluctuations (phonons or plasmons). Treating the radiation field as classical, an analytic solution for the evolution of the radiation intensity is derived and threshold conditions are obtained. The evolution toward stimulated emission shows a slow buildup followed by a rapid transition. Time scales of these two stages are analyzed.

Strauss, M.

1988-08-01

141

X-ray photoelectron spectroscopy analysis of organic materials irradiated with gas cluster ion beam  

SciTech Connect

Irradiation effect of gas cluster ion beams (GCIB) on organic materials were studied with X-ray photoelectron spectroscopy by comparison to that with Ar-monomer ions. In the case of polyimide, the intensity of both N-C = O and -C-O- bond decreased with 500 eV Ar monomer ion irradiation. On the other hand, there was no significant change in the XPS spectra after Ar-GCIB irradiation. From the size-selected GCIB irradiation study, the damages in polyimide decreased with increasing the cluster size owing to the reduction of energy per atoms.

Nakagiri, Motohiro; Toyoda, Noriaki; Yamada, Isao [Incubation center, Graduate school of engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2280 (Japan)

2011-01-07

142

Calibration of X-ray Imaging Devices for Accurate Intensity Measurement  

SciTech Connect

National Security Technologies (NSTec) has developed calibration procedures for X-ray imaging systems using NIST traceable sources. The X-ray sources that are used for calibration are both diode type and diode/fluorescer combinations. Calibrating the X-ray detectors is the key to accurate calibration of the X-ray sources. Both energy dispersive detectors and photodiodes measuring total flux were used. We have developed calibration techniques for the detectors using radioactive sources that are traceable to the National Institute of Standards and Technology (NIST). The German synchrotron at Physikalische Technische Bundestalt (PTB) is used to calibrate silicon photodiodes over the energy range from 50 eV to 60 keV. The measurements on X-ray cameras made using the NSTec X-ray sources have included the quantum efficiency averaged over all pixels, the camera counts per photon per pixel, and response variation across the sensor. The instrumentation required to accomplish the calibrations is described. X-ray energies ranged from 720 eV to 22.7 keV. The X-ray sources produce narrow energy bands, allowing us to determine the properties as a function of X-ray energy. The calibrations were done for several types of imaging devices. There were back illuminated and front illuminated CCD (charge coupled device) sensors, and a CID (charge injection device) type camera. The CCD and CID camera types differ significantly in some of their properties that affect the accuracy of X-ray intensity measurements. All cameras discussed here are silicon based. The measurements of quantum efficiency variation with X-ray energy are compared to models for the sensor structure. Cameras that are not back-thinned are compared to those that are.

Haugh, M. J., Charest, M., Ross, P., Lee, J. Schneider, M., Palmer, N., Teruya,

2012-06-01

143

CALIBRATION OF X-RAY IMAGING DEVICES FOR ACCURATE INTENSITY MEASUREMENT  

SciTech Connect

National Security Technologies (NSTec) has developed calibration procedures for X-ray imaging systems. The X-ray sources that are used for calibration are both diode type and diode/fluorescer combinations. Calibrating the X-ray detectors is key to accurate calibration of the X-ray sources. Both energy dispersive detectors and photodiodes measuring total flux were used. We have developed calibration techniques for the detectors using radioactive sources that are traceable to the National Institute of Standards and Technology (NIST). The German synchrotron at Physikalische Technische Bundestalt (PTB) is used to calibrate silicon photodiodes over the energy range from 50 eV to 60 keV. The measurements on X-ray cameras made using the NSTec X-ray sources have included quantum efficiency averaged over all pixels, camera counts per photon per pixel, and response variation across the sensor. The instrumentation required to accomplish the calibrations is described. X-ray energies ranged from 720 eV to 22.7 keV. The X-ray sources produce narrow energy bands, allowing us to determine the properties as a function of X-ray energy. The calibrations were done for several types of imaging devices. There were back illuminated and front illuminated CCD (charge coupled device) sensors, and a CID (charge injection device) type camera. The CCD and CID camera types differ significantly in some of their properties that affect the accuracy of X-ray intensity measurements. All cameras discussed here are silicon based. The measurements of quantum efficiency variation with X-ray energy are compared to models for the sensor structure. Cameras that are not back-thinned are compared to those that are.

Haugh, M J; Charest, M R; Ross, P W; Lee, J J; Schneider, M B; Palmer, N E; Teruya, A T

2012-02-16

144

An optimal target-filter system for electron beam generated x-ray spectra  

SciTech Connect

An electron beam generated x-ray spectrum consists of characteristic x rays of the target and continuous bremsstrahlung. The percentage of characteristic x rays over the entire energy spectrum depends on the beam energy and the filter thickness. To determine the optimal electron beam energy and filter thickness, one can either conduct many experimental measurements, or perform a series of Monte Carlo simulations. Monte Carlo simulations are shown to be an efficient tool for determining the optimal target-filter system for electron beam generated x-ray spectra. Three of the most commonly used low-energy x-ray metal targets (Cu, Zn and Mo) are chosen for this study to illustrate the power of Monte Carlo simulations.

Hsu, Hsiao-Hua; Vasilik, D.G. [Los Alamos National Lab., NM (United States); Chen, J. [GSF, Institut fur Strahlenbiologie, Neuherberg (Germany)

1994-04-01

145

The Effect of Tomosynthesis X-Ray Pulse Width on Measured Beam Quality  

Microsoft Academic Search

Tomosynthesis acquisition typically consists of a set of short x-ray pulses from an x-ray tube moved to different locations\\u000a relative to the object being imaged. The pulsed x-rays used in the acquisition exhibit a “pulsing effect” on the beam quality\\u000a results that is different from conventional mammography. We found that the measured exposure rates in term of mR per mAs

Baorui Ren; Andrew Smith; David Aizer; Don Kennedy; Jeffrey Yorker; Zhenxue Jing

2008-01-01

146

Beam Dynamics in a Linear Accelerator for Generations of Short Electron Beams and Femtosecond Hard X-ray Pulses  

NASA Astrophysics Data System (ADS)

We investigate a linear accelerator system capable of generating short electron beams and femtosecond hard X-ray pulses. We show a detailed design for a two-stage bunch compressor to generate the short electron beams in the linear accelerator. The bunch compressor system consists of two chicanes with a short system length that can compress an electron bunch of 0.6 nC and beam energy of 162 MeV, from 3 to 0.5 ps rms. One important design issue in the bunch compressor is to make as small growths of the emittance and energy spread as possible. The normalized horizontal emittance of 3 mm mrad is increased by approximately 10% due to coherent synchrotron radiation in the designed bunch compressor. Lattice distortions due to machine errors associate with quadrupole magnets, bending magnets and beam position monitors in the linear accelerator were investigated. It is shown that the lattice distortions due to the machine errors can be easily compensated by performing both orbit correction and dispersion correction in the linear accelerator. We have performed tolerance studies due to the various jitter sources in the linear accelerator to examine their sensitivities on the beam quality. From these results, it is shown that the linear accelerator system provides sufficient tolerances to maintain stable electron beams. We also investigated the generation of femtosecond hard X-ray pulses that may be provided by the interactions at 90\\circ of the short electron beams in the linear accelerator with a laser system. It is shown that 3.4× 106 photons within 10% bandwidth at 0.04 Å wavelength in about 350 fs rms pulse may be provided using the linear accelerator system. We presented studies on beam dynamics in the linear accelerator system that may provide the short beams and intense X-ray pulses.

Kim, Eun-San

2007-12-01

147

Synchrotron x-ray radiation from laser wakefield accelerated electron beams in a plasma channel  

NASA Astrophysics Data System (ADS)

Synchrotron x-ray radiation from laser wakefield accelerated electron beams was characterized at the HERCULES facility of the University of Michigan. A mono-energetic electron beam with energy up to 400 MeV was observed in the interaction of an ultra-short laser pulse with a super-sonic gas jet target. The experiments were performed at a peak intensity of 5×1019 W/cm2 by using an adaptive optic. The accelerated electron beam undergoes a so called "betatron" oscillation in an ion channel, where plasma electrons have been expelled by the laser ponderomotive force, and, therefore, emits synchrotron radiation. We observe broad synchrotron x-ray radiation extending up to 30 keV. We find that this radiation is emitted in a beam with a divergence angle as small as 12×4 mrad2 and can have a source size smaller than 3 microns and a peak brightness of 1022 photons/mm2/mrad2/second/0.1% bandwidth, which is comparable to currently existing 3rd generation conventional light sources. This opens up the possibility of using laser-produced "betatron" sources for many applications that currently require conventional synchrotron sources.

Matsuoka, T.; Kneip, S.; McGuffey, C.; Palmer, C.; Schreiber, J.; Huntington, C.; Horovitz, Y.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Thomas, A. G. R.; Yanovsky, V.; Phuoc, K. Ta; Mangles, S. P. D.; Najmudin, Z.; Maksimchuk, A.; Krushelnick, K.

2010-08-01

148

X-ray QPOs from the Ultra-luminous X-ray Source in M82: Evidence Against Beaming  

NASA Technical Reports Server (NTRS)

We report the discovery with the European Photon Imaging Camera (EPIC) CCD cameras onboard XMM-Newton of a 54 mHz quasiperiodic oscillation (QPO) in the greater than 2 keV X-ray flux from the ultra-luminous X-ray source (ULX) X41.4+60 in the starburst galaxy M82. This is the first detection of a QPO in the X-ray flux from an extra-Galactic ULX, and confirms that the source is a compact object. The QPO is detected in the combined PN and MOS data at the approx. 6sigma level, and separately at lower significances in both the PN and MOS instruments. It had a centroid frequency of 54.3 +/- 0.9 mHz, a coherence Q is identical with nu(sub 0)/Delta nu(sub fwhm) is approx. 5, and an amplitude (rms) in the 2 - 10 keV band of 8.5%. Below about 0.2 Hz the power spectrum can be described by a power-law with index approx. 1, and integrated amplitude (rms) of 13.5%. The X-ray spectrum requires a curving continuum, with a disk-blackbody (diskbb) at T = 3.1 keV providing an acceptable, but not unique, fit. A broad Fe line centered at 6.55 keV is required in all fits, but the equivalent width (EW) of the line is sensitive to the choice of continuum model. There is no evidence of a reflection component. The implied bolometric luminosity is approx. 4 - 5 x 10(exp 40) ergs/s. Data from several archival Rossi X-ray Timing Explorer (RXTE) pointings at M82 also show evidence for QPOs in the 50 - 100 mHz frequency range. Several Galactic black hole candidates (BHCs), including GRS 1915+105, GRO J1655-40, and XTE 1550-564, show QPOs in the same frequency range as the 50 - 100 mHz QPOs in X41.4+60, which at first glance suggests a possible connection with such objects. However, strong, narrow QPOs provide solid evidence for disk emission, and thus present enormous theoretical difficulties for models which rely on either geometrically or relativistically beamed emission to account for the high X-ray luminosities. We discuss the implications of our findings for models of the ULX sources.

Strohmayer, Tod E.; Mushotzky, Richard F.

2003-01-01

149

ANALYSIS AND MITIGATION OF X-RAY HAZARD GENERATED FROM HIGH INTENSITY LASER-TARGET INTERACTIONS  

SciTech Connect

Interaction of a high intensity laser with matter may generate an ionizing radiation hazard. Very limited studies have been made, however, on the laser-induced radiation protection issue. This work reviews available literature on the physics and characteristics of laser-induced X-ray hazards. Important aspects include the laser-to-electron energy conversion efficiency, electron angular distribution, electron energy spectrum and effective temperature, and bremsstrahlung production of X-rays in the target. The possible X-ray dose rates for several femtosecond Ti:sapphire laser systems used at SLAC, including the short pulse laser system for the Matter in Extreme Conditions Instrument (peak power 4 TW and peak intensity 2.4 x 10{sup 18} W/cm{sup 2}) were analysed. A graded approach to mitigate the laser-induced X-ray hazard with a combination of engineered and administrative controls is also proposed.

Qiu, R.; Liu, J.C.; Prinz, A.A.; Rokni, S.H.; Woods, M.; Xia, Z.; /SLAC; ,

2011-03-21

150

In situ micro-focused X-ray beam characterization with a lensless camera using a hybrid pixel detector.  

PubMed

Results of studies on micro-focused X-ray beam diagnostics using an X-ray beam imaging (XBI) instrument based on the idea of recording radiation scattered from a thin foil of a low-Z material with a lensless camera are reported. The XBI instrument captures magnified images of the scattering region within the foil as illuminated by the incident beam. These images contain information about beam size, beam position and beam intensity that is extracted during dedicated signal processing steps. In this work the use of the device with beams for which the beam size is significantly smaller than that of a single detector pixel is explored. The performance of the XBI device equipped with a state-of-the-art hybrid pixel X-ray imaging sensor is analysed. Compared with traditional methods such as slit edge or wire scanners, the XBI micro-focused beam characterization is significantly faster and does not interfere with on-going experiments. The challenges associated with measuring micrometre-sized beams are described and ways of optimizing the resolution of beam position and size measurements of the XBI instrument are discussed. PMID:24562554

Kachatkou, Anton; Marchal, Julien; van Silfhout, Roelof

2014-03-01

151

TECHNICAL NOTE: Neutron contamination of X-ray beams produced by the Varian Clinac 1800  

Microsoft Academic Search

High energy X-ray beams produced by medical accelerators are contaminated with neutrons as a result of photon interactions with the target, flattering filter and collimator. It is important to evaluate the neutron dose to patients undergoing X-ray therapy and a number of studies have been conducted to determine dose levels in the patient plane produced by neutrons transmitted through the

P. H. McGinley; J. C. Landry

1989-01-01

152

Choice of material for HVL measurements in megavoltage x-ray beams  

Microsoft Academic Search

The relative sensitivity of the half-value layer (HVL) method as a quality index for megavoltage x-ray beams is examined by theoretical calculation and experimental measurements for 4-, 6-, 10-, and 25-MV x-ray beams. It is shown that lower atomic number materials are more sensitive to beam quality changes than higher atomic number materials, and that aluminum is a reasonable choice

Jerome A. Meli; R. Nath

1985-01-01

153

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

SciTech Connect

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.

Hruszkewycz, S. O.; Harder, R.; Xiao, X.; Fuoss, P. H. (Materials Science Division); ( XSD)

2010-12-01

154

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

SciTech Connect

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.

Hruszkewycz, S. O.; Fuoss, P. H. [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Harder, R.; Xiao, X. [X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2010-12-15

155

Intensity-Modulated Advanced X-ray Source (IMAXS) for Homeland Security Applications  

NASA Astrophysics Data System (ADS)

X-ray cargo inspection systems for the detection and verification of threats and contraband require high x-ray energy and high x-ray intensity to penetrate dense cargo. On the other hand, low intensity is desirable to minimize the radiation footprint. A collaboration between HESCO/PTSE Inc., Schonberg Research Corporation and Rapiscan Laboratories, Inc. has been formed in order to design and build an Intensity-Modulated Advanced X-ray Source (IMAXS). Such a source would allow cargo inspection systems to achieve up to two inches greater imaging penetration capability, while retaining the same average radiation footprint as present fixed-intensity sources. Alternatively, the same penetration capability can be obtained as with conventional sources with a reduction of the average radiation footprint by about a factor of three. The key idea is to change the intensity of the source for each x-ray pulse based on the signal strengths in the inspection system detector array during the previous pulse. In this paper we describe methods to accomplish pulse-to-pulse intensity modulation in both S-band (2998 MHz) and X-band (9303 MHz) linac sources, with diode or triode (gridded) electron guns. The feasibility of these methods has been demonstrated. Additionally, we describe a study of a shielding design that would allow a 6 MV X-band source to be used in mobile applications.

Langeveld, Willem G. J.; Johnson, William A.; Owen, Roger D.; Schonberg, Russell G.

2009-03-01

156

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

NASA Technical Reports Server (NTRS)

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.

Carpenter, P. K.

2005-01-01

157

Modulation of hard x-ray beam profiles by Borrmann pyramid  

SciTech Connect

Spatial modulation of hard x-ray beam profiles is reported, using the 'Borrmann pyramid' formed in dual Bragg diffraction of a single crystal, where a small angular change of the incident beam is magnified to span the entire pyramid base. As an attempt, it is demonstrated using hard x rays by (1) the linear shift of a micrometer sized mask; (2) the partial blockade of a two micron beam; and (3) the millimeter shadow of a nanoscale gold strip, which shows the potential application of Borrmann pyramids in the form of an enlarged x-ray image.

Xu, G. [Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Britten, J. [Chemistry Department, McMaster University, Hamilton, Ontario L8S 4L8 (Canada)

2008-01-15

158

Beam-induced damage on diffractive hard X-ray optics  

PubMed Central

The issue of beam-induced damage on diffractive hard X-ray optics is addressed. For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both ambient and inert atmospheres. Diffraction gratings fabricated by three different techniques are considered: electroplated Au gratings both with and without the polymer mold, and Ir-coated Si gratings. The beam-induced damage is monitored by X-ray diffraction and evaluated using scanning electron microscopy.

Nygard, K.; Gorelick, S.; Vila-Comamala, J.; Farm, E.; Bergamaschi, A.; Cervellino, A.; Gozzo, F.; Patterson, B. D.; Ritala, M.; David, C.

2010-01-01

159

Effect of area x-ray beam equalization on image quality and dose in digital mammography  

NASA Astrophysics Data System (ADS)

In mammography, thick or dense breast regions persistently suffer from reduced contrast-to-noise ratio (CNR) because of degraded contrast from large scatter intensities and relatively high noise. Area x-ray beam equalization can improve image quality by increasing the x-ray exposure to under-penetrated regions without increasing the exposure to other breast regions. Optimal equalization parameters with respect to image quality and patient dose were determined through computer simulations and validated with experimental observations on a step phantom and an anthropomorphic breast phantom. Three parameters important in equalization digital mammography were considered: attenuator material (Z = 13-92), beam energy (22-34 kVp) and equalization level. A Mo/Mo digital mammography system was used for image acquisition. A prototype 16 × 16 piston driven equalization system was used for preparing patient-specific equalization masks. Simulation studies showed that a molybdenum attenuator and an equalization level of 20 were optimal for improving contrast, CNR and figure of merit (FOM = CNR2/dose). Experimental measurements using these parameters showed significant improvements in contrast, CNR and FOM. Moreover, equalized images of a breast phantom showed improved image quality. These results indicate that area beam equalization can improve image quality in digital mammography.

Wong, Jerry; Xu, Tong; Husain, Adeel; Le, Huy; Molloi, Sabee

2004-08-01

160

77 FR 12226 - Sadex Corp.; Filing of Food Additive Petition (Animal Use); Electron Beam and X-Ray Sources for...  

Federal Register 2010, 2011, 2012, 2013

...Animal Use); Electron Beam and X-Ray Sources for Irradiation of Poultry...for the safe use of electron beam and x-ray sources for irradiation of poultry...for the safe use of electron beam and x- ray sources for irradiation of...

2012-02-29

161

Micro-beam X-ray fluorescence and absorption imaging techniques at the IAEA Laboratories  

NASA Astrophysics Data System (ADS)

X-ray tube based, micro-beam X-ray fluorescence scanning spectrometer has been equipped with two energy dispersive X-ray detectors. The two-detector configuration allows for simultaneous collection of X-ray fluorescence (XRF) and transmitted X-ray beam signals with a spatial resolution in the range of 10-50 ?m, depending on the X-ray focussing element in use. The XRF signal is collected with a standard, liquid nitrogen cooled Si(Li) detector. The X-ray beam transmitted through the sample is acquired with a thermoelectrically cooled, silicon drift (SD) detector. The data acquisition is carried out in a fully automatic way under control of the SPECTOR-LOCATOR software. The software controls the scanning procedure and X-ray spectra acquisition during the scan. The energy dispersive X-ray spectra collected at every "pixel" are stored for off-line processing. For selected regions of interest (ROI's), the element maps are constructed and displayed on-line. The spectrometer has been used for mapping elemental distributions and for performing 2D- and 3D-tomograpic imaging of minute objects in X-ray absorption and in X-ray fluorescence mode. A unique feature of the described system is simultaneous utilization of the two detectors, Si(Li) and SD, which adds new options for quantitative analysis and data interpretation. Examples of elemental mapping and 3D tomographic imaging as well as the advanced features of the SPECTOR-LOCATOR measurement control and data acquisition software are presented in this work.

Wegrzynek, Dariusz; Markowicz, A.; Bamford, S.; Chinea-Cano, E.; Bogovac, M.

2005-04-01

162

The soft X-ray spectrum of Capella - Discovery of intense line emission  

NASA Technical Reports Server (NTRS)

A soft X-ray spectrum of Capella has been obtained with the HEAO 1 satellite. Only models which include intense line emission at 0.85 keV can adequately explain the data. The spectrum is consistent with emission from an isothermal solar-abundance plasma with a temperature of 10.5 million (+ or - 2.8 million) K. It is also consistent with a blend of temperatures between 4 and 20 million K. The intensity of the X-ray emission is constant over 2 days and similar to the intensity observed by ANS.

Cash, W.; Bowyer, S.; Charles, P. A.; Lampton, M.; Garmire, G.; Riegler, G.

1978-01-01

163

Food irradiation technology using electron beams and x-rays  

Microsoft Academic Search

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation (e.g., energetic electrons and x-rays) to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include for example, the disinfestation of insects in fruits and

R. B. Miller

2002-01-01

164

X-ray Absorption Imaging of High-Intensity Discharge Lamps Using Monochromatic Synchrotron Radiation  

NASA Astrophysics Data System (ADS)

We will report results from the imaging of Hg vapor in high-intensity discharge lamps using synchrotron radiation and digital detectors. These measurements extend previous work on x-ray absorption imaging in arc lamps using an x-ray tube and a passive phosphor image plate detector^i. The large x-ray flux obtained from the Advanced Photon Source (Argonne National Laboratory) combined with the electronic gating capabilities of an intensified charge-coupled device detector have allowed us to obtain time-resolved Hg distributions with high spatial resolution. Monochromatic synchrotron radiation improves the accuracy over what can be obtained with quasi-continuum radiation from an x-ray tube source. ^iJ. J. Curry, M. Sakai, and J. E. Lawler, Journal of Applied Physics 84, 3066 (1998).

Curry, John J.; Sansonetti, Craig J.; Hechtfischer, Ulrich; Adler, Helmar G.

2002-10-01

165

SLAC\\/DESY International Workshop on Interactions of Intense SubPicosecond X-Rays with Matter, Stanford, CA, January 23-24, 1997  

Microsoft Academic Search

This is the proceedings volume of the 1997 SLAC\\/DESY International Workshop on Interactions of Intense Sub-picosecond X-Ray Pulses with Matter. The workshop theme evolved out of design and R&D studies, undertaken at SLAC, DESY, and elsewhere [1,2], of the new class of linac-driven X-Ray Free Electron Lasers (XRFELs) operating with photocathode-based, low-emittance electron beams in the Self-Amplified Spontaneous Emission (SASE)

Tatchyn

1998-01-01

166

Quantitative Analysis of Asbestos Minerals by the Reference Intensity X-Ray Diffraction Procedure  

Microsoft Academic Search

X-ray diffraction analysis of asbestos-bearing materials has been completed using reference intensity ratios. The procedure includes a sample preparation method for suspension of a finely pulverized material and for deorienting the particles on a glass fiber filter. Diffraction intensifies are corrected for matrix and transparency. Reference intensity ratios have been determined in this study for chrysotile, amosite, anthophyllite, crocidolite, and

BRIANT L. DAVIS

1990-01-01

167

21 CFR 892.1610 - Diagnostic x-ray beam-limiting device.  

Code of Federal Regulations, 2011 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1610 Diagnostic x-ray beam-limiting device. (a) Identification....

2011-04-01

168

21 CFR 892.1610 - Diagnostic x-ray beam-limiting device.  

Code of Federal Regulations, 2010 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1610 Diagnostic x-ray beam-limiting device. (a) Identification....

2010-04-01

169

21 CFR 892.1610 - Diagnostic x-ray beam-limiting device.  

Code of Federal Regulations, 2012 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1610 Diagnostic x-ray beam-limiting device. (a) Identification....

2012-04-01

170

21 CFR 892.1610 - Diagnostic x-ray beam-limiting device.  

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1610 Diagnostic x-ray beam-limiting device. (a) Identification....

2014-04-01

171

21 CFR 892.1610 - Diagnostic x-ray beam-limiting device.  

Code of Federal Regulations, 2013 CFR

... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1610 Diagnostic x-ray beam-limiting device. (a) Identification....

2013-04-01

172

Electron-beam-based sources of ultrashort x-ray pulses  

SciTech Connect

A review of various methods for generation of ultrashort X-ray pulses using relativistic electron beam from conventional accelerators is presented. Both spontaneous and coherent emission of electrons are considered.

Zholents, A. (Accelerator Systems Division (APS))

2010-01-01

173

Diamond X-ray beam-position monitoring using signal readout at the synchrotron radiofrequency.  

PubMed

Single-crystal diamond is a material with great potential for the fabrication of X-ray photon beam-position monitors with submicrometre spatial resolution. Low X-ray absorption combined with radiation hardness and excellent thermal-mechanical properties make possible beam-transmissive diamond devices for monitoring synchrotron and free-electron laser X-ray beams. Tests were made using a white bending-magnet synchrotron X-ray beam at DESY to investigate the performance of a position-sensitive diamond device using radiofrequency readout electronics. The device uniformity and position response were measured in a 25 microm collimated X-ray beam with an I-Tech Libera ;Brilliance' system. This readout system was designed for position measurement and feedback control of the electron beam in the synchrotron storage ring, but, as shown here, it can also be used for accurate position readout of a quadrant-electrode single-crystal diamond sensor. The centre-of-gravity position of the F4 X-ray beam at the DORIS III synchrotron was measured with the diamond signal output digitally sampled at a rate of 130 Msample s(-1) by the Brilliance system. Narrow-band filtering and digital averaging of the position signals resulted in a measured position noise below 50 nm (r.m.s.) for a 10 Hz bandwidth. PMID:20567077

Morse, J; Solar, B; Graafsma, H

2010-07-01

174

The correction of reflection intensities for incomplete absorption of high-energy X-rays in the CCD phosphor  

SciTech Connect

It is shown that incomplete absorption of the X-ray beam in the phosphor of an area detector causes an incident-angle dependence of the recorded X-ray intensities. An energy scan of a SMART-6000 CCD (charge-coupled device) phosphor using synchrotron radiation shows the correction to be of importance above about 17 keV. Intensities of single reflections, each collected several times at different angles of incidence on the phosphor surface, show a pronounced angle-dependence at shorter wavelengths. Both conventional structural refinement and multipole charge density studies confirm that an oblique-incidence correction leads to improved quality of the results. Atomic displacement parameters will be systematically biased when the correction is not applied. For a {lambda} = 0.394 {angstrom} data set, neglecting the correction gives rise to artifacts in the deformation density maps that are likely to lead to misinterpretation of the experimental results.

Wu, G.; Rodrigues, B.L.; Coppens, P. (SUNYB)

2009-03-24

175

Spectrum bandwidth narrowing of Thomson scattering X-rays with energy chirped electron beams from laser wakefield acceleration  

NASA Astrophysics Data System (ADS)

We study incoherent Thomson scattering between an ultrashort laser pulse and an electron beam accelerated from a laser wakefield. The energy chirp effects of the accelerated electron beam on the final radiation spectrum bandwidth are investigated. It is found that the scattered X-ray radiation has the minimum spectrum width and highest intensity as electrons are accelerated up to around the dephasing point. Furthermore, it is proposed that the electron acceleration process inside the wakefield can be studied by use of 90° Thomson scattering. The dephasing position and beam energy chirp can be deduced from the intensity and bandwidth of the scattered radiation.

Xu, Tong; Chen, Min; Li, Fei-Yu; Yu, Lu-Le; Sheng, Zheng-Ming; Zhang, Jie

2014-01-01

176

Beam Collimation using Polycapillary X-ray optics for Large Area Diffraction Applications  

Microsoft Academic Search

Polycapillary optics, arrays of thin-walled, hollow borosilicate glass channels, can be employed to redirect, collimate and focus x-ray photons. Polycapillary collimating optics collect x-rays over a wide solid angle (as large as lo-15 degrees cone angle) and a large energy bandwidth and provide a quasi-parallel beam with a small divergence (a few milliradians). Parallel beam geometry and uniform local divergence

S. D. Padiyar; Hui Wang; M. V. Gubarev; W. M. Gibson; C. A. MacDonald

177

Performance Characteristics Of An Intensity Modulated Advanced X-Ray Source (IMAXS) For Homeland Security Applications  

SciTech Connect

X-ray cargo inspection systems for the detection and verification of threats and contraband must address stringent, competitive performance requirements. High x-ray intensity is needed to penetrate dense cargo, while low intensity is desirable to minimize the radiation footprint, i.e. the size of the controlled area, required shielding and the dose to personnel. In a collaborative effort between HESCO/PTSE Inc., XScell Corp., Stangenes Industries, Inc. and Rapiscan Laboratories, Inc., an Intensity Modulated Advanced X-ray Source (IMAXS) was designed and produced. Cargo inspection systems utilizing such a source have been projected to achieve up to 2 inches steel-equivalent greater penetration capability, while on average producing the same or smaller radiation footprint as present fixed-intensity sources. Alternatively, the design can be used to obtain the same penetration capability as with conventional sources, but reducing the radiation footprint by about a factor of three. The key idea is to anticipate the needed intensity for each x-ray pulse by evaluating signal strength in the cargo inspection system detector array for the previous pulse. The IMAXS is therefore capable of changing intensity from one pulse to the next by an electronic signal provided by electronics inside the cargo inspection system detector array, which determine the required source intensity for the next pulse. We report on the completion of a 9 MV S-band (2998 MHz) IMAXS source and comment on its performance.

Langeveld, Willem G. J.; Brown, Craig; Condron, Cathie; Ingle, Mike [Rapiscan Laboratories, Inc., 520 Almanor Ave., Sunnyvale, CA 94085 (United States); Christensen, Phil A.; Johnson, William A.; Owen, Roger D. [HESCO/PTSE Inc., 2501 Monarch St., Alameda, CA 94501 (United States); Hernandez, Michael; Schonberg, Russell G. [XScell Corp., 2134 Old Middlefield Way, Mountain View, CA 94043 (United States); Ross, Randy [Stangenes Industries, Inc., 1052 East Meadow Circle, Palo Alto, CA 94303 (United States)

2011-06-01

178

Beam collimation with polycapillary x-ray optics for high contrast high resolution monochromatic imaging  

SciTech Connect

Monochromatic imaging can provide better contrast and resolution than conventional broadband radiography. In broadband systems, low energy photons do not contribute to the image, but are merely absorbed, while high energy photons produce scattering that degrades the image. By tuning to the optimal energy, one can eliminate undesirable lower and higher energies. Monochromatization is achieved by diffraction from a single crystal. A crystal oriented to diffract at a particular energy, in this case the characteristic line energy, diffracts only those photons within a narrow range of angles. The resultant beam from a divergent source is nearly parallel, but not very intense. To increase the intensity, collimation was performed with polycapillary x-ray optics, which can collect radiation from a divergent source and redirect it into a quasi parallel beam. Contrast and resolution measurements were performed with diffracting crystals with both high and low angular acceptance. Testing was first done at 8 keV with an intense copper rotating anode x-ray source, then 17.5 keV measurements were made with a low power molybdenum source. At 8 keV, subject contrast was a factor of five higher than for the polychromatic case. At 17.5 keV, monochromatic contrast was two times greater than the conventional polychromatic contrast. The subject contrasts measured at both energies were in good agreement with theory. An additional factor of two increase in contrast, for a total gain of four, is expected at 17.5 keV from the removal of scatter. Scatter might be simply removed using an air gap, which does not degrade resolution with a parallel beam.

Sugiro, Francisca R.; Li Danhong; MacDonald, C.A. [Health Imaging Division, Eastman Kodak Company, Rochester, New York 14650 (United States); Center for X-ray Optics, University at Albany, Albany, New York 12222 (United States)

2004-12-01

179

Beam collimation with polycapillary x-ray optics for high contrast high resolution monochromatic imaging.  

PubMed

Monochromatic imaging can provide better contrast and resolution than conventional broadband radiography. In broadband systems, low energy photons do not contribute to the image, but are merely absorbed, while high energy photons produce scattering that degrades the image. By tuning to the optimal energy, one can eliminate undesirable lower and higher energies. Monochromatization is achieved by diffraction from a single crystal. A crystal oriented to diffract at a particular energy, in this case the characteristic line energy, diffracts only those photons within a narrow range of angles. The resultant beam from a divergent source is nearly parallel, but not very intense. To increase the intensity, collimation was performed with polycapillary x-ray optics, which can collect radiation from a divergent source and redirect it into a quasi parallel beam. Contrast and resolution measurements were performed with diffracting crystals with both high and low angular acceptance. Testing was first done at 8 keV with an intense copper rotating anode x-ray source, then 17.5 keV measurements were made with a low power molybdenum source. At 8 keV, subject contrast was a factor of five higher than for the polychromatic case. At 17.5 keV, monochromatic contrast was two times greater than the conventional polychromatic contrast. The subject contrasts measured at both energies were in good agreement with theory. An additional factor of two increase in contrast, for a total gain of four, is expected at 17.5 keV from the removal of scatter. Scatter might be simply removed using an air gap, which does not degrade resolution with a parallel beam. PMID:15651611

Sugiro, Francisca R; Li, Danhong; MacDonald, C A

2004-12-01

180

Using DCM pitch modulation and feedback to improve long term X-ray beam stability  

NASA Astrophysics Data System (ADS)

In this paper we demonstrate significant improvements to the stability of the monochromatic X-ray beam intensity on several beamlines at Diamond, using a modulation of the pitch axis of the DCM with a piezoelectric actuator. The modulation is detected on an intensity diagnostic (e.g. an ion chamber) using a software lock-in technique. The detected amplitude and phase are used in a feedback to keep the DCM at the peak of the rocking curve, or any arbitrary position 'off-peak' which might be desired to detune the DCM and reject unwanted harmonics. A major advantage of this software based system is the great flexibility offered, using standard, readily available instrumentation. Measurements of the short and long-term performance of the feedback on several beamlines are presented, and the limitations of such a feedback are discussed.

Bloomer, C.; Dent, A.; Diaz-Moreno, S.; Dolbnya, I.; Pedersen, U.; Rehm, G.; Tang, C.; Thomas, C.

2013-03-01

181

X-ray projection microscopy and cone-beam microtomography  

NASA Astrophysics Data System (ADS)

A laboratory sized X-ray projection microscope and microtomographic imaging system is being developed. High resolution two-dimensional images can be recorded rapidly using a high resolution phosphor and a cooled slow scan CCD camera. Three-dimensional information can be derived from the high resolution two-dimensional images by generating stereo pairs or by reconstructing the complete tomographic image. Real time stereo pairs can be produced by rapidly moving the position of the electron spot between two locations on the thin film target, thus irradiating the specimen with X-rays from two spatially distinct directions. For high resolution tomography, or microtomography, the two-dimensional images are recorded for a large number of different orientations of the specimen. The experimental results reveal the quantitative relationship between the accuracy of the reconstructed image and the experimental parameters such as object shape, orientation, and position.

Wang, G.; Lin, T. H.; Cheng, P. C.; Shinozaki, D. M.; Newberry, S. P.

182

Femtosecond X-ray-induced explosion of C60 at extreme intensity.  

PubMed

Understanding molecular femtosecond dynamics under intense X-ray exposure is critical to progress in biomolecular imaging and matter under extreme conditions. Imaging viruses and proteins at an atomic spatial scale and on the time scale of atomic motion requires rigorous, quantitative understanding of dynamical effects of intense X-ray exposure. Here we present an experimental and theoretical study of C60 molecules interacting with intense X-ray pulses from a free-electron laser, revealing the influence of processes not previously reported. Our work illustrates the successful use of classical mechanics to describe all moving particles in C60, an approach that scales well to larger systems, for example, biomolecules. Comparisons of the model with experimental data on C60 ion fragmentation show excellent agreement under a variety of laser conditions. The results indicate that this modelling is applicable for X-ray interactions with any extended system, even at higher X-ray dose rates expected with future light sources. PMID:24969734

Murphy, B F; Osipov, T; Jurek, Z; Fang, L; Son, S-K; Mucke, M; Eland, J H D; Zhaunerchyk, V; Feifel, R; Avaldi, L; Bolognesi, P; Bostedt, C; Bozek, J D; Grilj, J; Guehr, M; Frasinski, L J; Glownia, J; Ha, D T; Hoffmann, K; Kukk, E; McFarland, B K; Miron, C; Sistrunk, E; Squibb, R J; Ueda, K; Santra, R; Berrah, N

2014-01-01

183

Asymmetrically cut crystal pair as x-ray magnifier for imaging at high intensity laser facilities  

SciTech Connect

The potential of an x-ray magnifier prepared from a pair of asymmetrically cut crystals is studied to explore high energy x-ray imaging capabilities at high intensity laser facilities. OMEGA-EP and NIF when irradiating mid and high Z targets can be a source of high-energy x-rays whose production mechanisms and use as backlighters are a subject of active research. This paper studies the properties and potential of existing asymmetric cut crystal pairs from the National Institute of Standards and Technology (NIST) built in a new enclosure for imaging x-ray sources. The technique of the x-ray magnifier has been described previously. This new approach is aimed to find a design that could be used at laser facilities by magnifying the x-ray source into a screen far away from the target chamber center, with fixed magnification defined by the crystals' lattice spacing and the asymmetry angles. The magnified image is monochromatic and the imaging wavelength is set by crystal asymmetry and incidence angles. First laboratory results are presented and discussed.

Szabo, C. I.; Feldman, U. [Artep Inc., 2922 Excelsior Spring Circle, Ellicott City, Maryland 21042 (United States); Seely, J. F. [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States); Curry, J. J.; Hudson, L. T.; Henins, A. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)

2010-10-15

184

Palm-top size X-ray microanalyzer using a pyroelectric focused electron beam with 100-micro-meter diameter  

NASA Astrophysics Data System (ADS)

We have developed a palm-top size EPMA (electron probe X-ray microanalyzer), operated by 3 V electric battery except for a rotary vacuum pump. The electron beam was generated by a pyroelectric single crystal, LiTaO3. A needle was used to make a focused electron beam. The smallest beam size was 100 ?m on the sample surface. The X-ray spectra were measured through a Kapton window by a Si-PIN detector for a model specimen containing TiO2 and MnO2 particles, which was an aerosol model specimen, where TiO2 and MnO2 particles of size about 100-200 ?m were separated by a few hundreds micrometers. By moving the sample stage manually, the X-ray spectra were measured for 300 s each by 300 ?m e-beam, and the measured X-ray intensities were strong enough for identification of the major element in individual 100-200 ?m size aerosol particles.

Kawai, Jun; Ohtani, Issei; Imanishi, Akira; Imashuku, Susumu

2014-04-01

185

Structure and intensity of x-ray radiation in a laser plasma-wall interaction  

NASA Astrophysics Data System (ADS)

Intense soft x-ray radiation is observed when a high temperature laser produced plasma collides with a solid surface (wall). The laser plasma is produced by Nd:YAG laser radiation (0.53 micrometers ; 200 mJ; 3 ns; 5x1012 w/cm2 focused onto a Mg target. The wall is placed in the path of the plasma expansion. Two experimental techniques are used. 1) One-dimensional x-ray images of the plasma-wall gap formed by a slit are observed using an absolutely calibrated CCD linear array. 2) X-ray spectra of [H]- and [He]-like Mg ions are recorded using a crystal focusing x-ray von Hamos spectrometer. At a measured electron temperature of Te equals 195 eV, emission of [He]-like ions Mg XI gives the main contribution to the observed x-ray intensity. The spatial structure and the intensity of the radiation are studied at various laser plasma-wall distances (r0 equals 0.3 - 3.0 mm). Intense radiation near the wall is caused by an electron density jump in a shockwave formed in front of the wall. At small wall distances r0<intensity exceeds the emission from the laser plasma itself. At distances r0$GTR$GTRv(tau) the radiation causes recombination processes. These results are important for developing collision and recombination schemes for x-ray lasers in colliding plasmas.

Shevelko, Alexander P.; Knight, Larry V.; Peatross, Justin; Wang, Quan

2001-12-01

186

Soft X-Ray Emission and Charged Particles Beams from a Plasma Focus of Hundreds Joules  

SciTech Connect

In a new stage of characterization of our plasma focus devices of hundred and tens of joules (PF-400J and PF-50J), preliminary series of measurements on soft X-ray and ion beams have been performed in the device PF-400J (176-539 J, 880 nF, T/4 {approx}300 ns). The device was operated in hydrogen to 7 mbar of pressure . The temporal and spatial X-ray characteristics are investigated by means filtered PIN diodes and a multipinhole camera. Graphite collectors, operating in the bias ion collector mode, are used to estimate the characteristic ion energy using the time flight across the probe array. The time of the ion beam emission to be correlated with plasma emission events associated with the soft X-ray pulses detected by the probes. Temporal correlations between soft X-ray signals and ion beams are performed.

Silva, Patricio; Moreno, Jose; Soto, Leopoldo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Pavez, Cristian [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Universidad de Concepcion, Facultad de Ciencias, Departamento de Fisica, Concepcion (Chile); Arancibia, Jaime [Universidad de Chile, Facultad de Ciencias, Departamento de Fisica, Santiago (Chile)

2006-12-04

187

Coherent x-ray scatter projection imaging using an array of monoenergetic pencil beams  

NASA Astrophysics Data System (ADS)

Traditional projection x-ray imaging utilizes only the information from the primary photons. Low-angle coherent scatter images can be made simultaneous to the primary images and provide additional information. To speed up acquisition time for coherent scatter projection imaging, we developed disentangling algorithms for the overlapping scatter patterns generated by multi pencil-beam geometries. A system at the Canadian Light Source synchrotron was configured which utilizes a custom collimator designed to convert a 33.17 keV monoenergetic fan beam from a Laue monochromator into multiple pencil beams by using 3 mm thick tungsten alloy stoppers. The pencil beams then travel through the sample and are absorbed by a tungsten bar. A digital flat panel detector records the superimposed scatter patterns from the beams. The sample is scanned through the beams using an automated step-and-shoot setup. The pixel value of the coherent scatter image is generated by integrating the radial profile (scatter intensity versus scattering angle) over an angular range. An MLEM-based iterative method and a least-squares method were developed to disentangle the scatter patterns. Although past work has primarily been applied to medicine, other applications include non-destructive testing and security.

Landheer, Karl; Johns, Paul C.

2012-05-01

188

Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes  

NASA Technical Reports Server (NTRS)

Relativisitic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and space reuseable launch vehicles (sRLVs). The monoenergetic beam is modeled in cylindrical symetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremsstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

Krause, L. Habsh; Gilchrist, B. E.; Nishikawa, Ken-Ichi

2013-01-01

189

Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes  

NASA Astrophysics Data System (ADS)

Relativistic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and suborbital Reusable Launch Vehicle (sRLV) altitudes. The monoenergetic beam is modeled in cylindrical symmetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremmstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry that relies on sRLVs with a nominal apogee of 100 km. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

Habash Krause, L.; Gilchrist, B. E.; Nishikawa, K.; Williams, A.

2013-12-01

190

PBFA II lithium beam characterization from inner-shell x-ray images  

SciTech Connect

The Particle Beam Fusion Accelerator (PBFA II) is now driving targets with ICF-relevant lithium ion beams. During the most recent lithium beam target series, time-integrated x-ray pinhole cameras viewed the ion-induced inner-shell x-ray fluorescence from the central gold cone target and a titanium-coated strip. Ion-beam profiles at a nominal 10-mm radius and fixed azimuthal direction were obtained from images of the Ti [ital K][sub [alpha

Moats, A.R.; Derzon, M.S.; Chandler, G.A.; Dukart, R.J.; Haill, T.A. (Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185 (United States))

1995-01-01

191

X-ray energy dependence of the properties of the focused beams produced by polycapillary X-ray lens.  

PubMed

We investigated X-ray energy distribution in an X-ray microbeam produced by a polycapillary X-ray lens in combination with a sealed-type X-ray tube. This polycapillary X-ray lens has an output focal distance (OFD) of approximately 15 mm. The size of the X-ray microbeam and its OFD were estimated by using a wire scanning method. In our case, the sizes of the X-ray microbeams at the output focal distance were 49 microm for Mo L(alpha), 36 microm for W L(alpha), and 28 microm for Mo K(alpha). The spot sizes depend on the energy of the X-ray fluorescence. The reason for the energy dependence is that X-ray capillary optics is based on the principle of propagation through glass capillaries by means of X-ray total external reflection. The evaluated OFD values of Mo L(alpha) and Mo K(alpha) were slightly changed in 17 microm. However, a deviation of 100 microm from the OFD caused only a 3% increase of the focal spot size. Therefore, we concluded that the OFD showed no significant dependence on X-ray energy. PMID:18614823

Matsuda, Akinori; Nodera, Yuta; Nakano, Kazuhiko; Tsuji, Kouichi

2008-07-01

192

Quantifying amorphous content of lactose using parallel beam X-ray powder diffraction and whole pattern fitting.  

PubMed

The objective of this study was to demonstrate the applicability of parallel beam X-ray powder diffraction (XRPD) and a new method for whole pattern fitting to the quantification of the residual amount of amorphous content in a pharmaceutical solid using lactose as a model system. Lactose monohydrate, prepared by slurry conversion of anhydrous lactose, was mixed with different amounts of amorphous lactose produced by lyophilization. X-ray powder diffractograms of each mixture were recorded and analyzed by whole pattern fitting using Percentage Crystallinity Determination Software from Kratos Analytical Inc. The polycapillary X-ray optic, which provides a parallel beam of X-radiation, has advantages over Bragg-Brentano Optics with respect to sample height artifacts. Significant shifts in peak position with changes in sample height of lactose monohydrate were observed using Bragg-Brentano Optics while no change was detected for the polycapillary X-ray optic. A technique to normalize all diffractograms to have the same total integrated intensity was necessary to eliminate tube fluctuation effects. After normalization, the amorphous content of lactose in the range of 1-10% was reproducibly predicted (small standard deviation between samplings) using whole pattern fitting. The limit of detection was calculated to be 0.37% amorphous content. The results indicated that parallel beam XRPD and whole pattern fitting can provide accurate analysis of relatively small amounts of amorphous content in pharmaceuticals compared to typical XRPD analysis. PMID:11451643

Chen, X; Bates, S; Morris, K R

2001-08-01

193

X-ray laser  

DOEpatents

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

Nilsen, Joseph (Livermore, CA)

1991-01-01

194

A method for implementing the diffraction of a widely divergent X-ray beam  

SciTech Connect

A method for implementing the diffraction of a widely divergent characteristic X-ray beam from a standard X-ray tube with a linear focal spot was improved. X rays, passing through a diaphragm 30 {mu}m in diameter, diffract from a crystal adjacent to the diaphragm. The crystal, together with a photographic plate, rotates around the axis perpendicular to the plate. It is shown that the diffraction image is a set of hyperbolas in this case. The equations of the hyperbolas are obtained and investigated. A method for interpreting the diffraction images in the case of small crystal asymmetry is proposed.

Avetyan, K. T.; Arakelyan, M. M., E-mail: marakelyan@ysu.am [Yerevan State University (Armenia)

2008-11-15

195

Proposal for an x-ray free electron laser oscillator with intermediate energy electron beam.  

PubMed

Harmonic lasing of low-gain free electron laser oscillators has been experimentally demonstrated in the terahertz and infrared regions. Recently, the low-gain oscillator has been reconsidered as a promising candidate for hard x-ray free electron lasers, through the use of high reflectivity, high-resolution x-ray crystals. In this Letter, it is proposed to utilize a crystal-based cavity resonant at a higher harmonic of the undulator radiation, together with phase shifting, to enable harmonic lasing of the x-ray free electron laser oscillator, and hence allow the generation of hard x-ray radiation at a reduced electron beam energy. Results show that fully coherent free electron laser radiation with megawatt peak power, in the spectral region of 10-25 keV, can be generated with a 3.5 GeV electron beam. PMID:22400748

Dai, Jinhua; Deng, Haixiao; Dai, Zhimin

2012-01-20

196

A water-cooled x-ray monochromator for using off-axis undulator beam.  

SciTech Connect

Undulator beamlines at third-generation synchrotrons x-ray sources are designed to use the high-brilliance radiation that is contained in the central cone of the generated x-ray beams. The rest of the x-ray beam is often unused. Moreover, in some cases, such as in the zone-plate-based microfocusing beamlines, only a small part of the central radiation cone around the optical axis is used. In this paper, a side-station branch line at the Advanced Photon Source that takes advantage of some of the unused off-axis photons in a microfocusing x-ray beamline is described. Detailed information on the design and analysis of a high-heat-load water-cooled monochromator developed for this beamline is provided.

Khounsary, A.; Maser, J.

2000-12-11

197

Comparison of Laser and X-Ray Focal Images for a Single OMEGA Laser Beam  

NASA Astrophysics Data System (ADS)

A single OMEGA laser beam is simultaneously focused on a flat gold target and in an equivalent-target-plane (ETP) setup. The x-ray emission is imaged with a Kirkpatrick-Baez microscope. The x-ray and ETP images are compared, and the measured x-ray conversion is compared with simulations. The x-ray and ETP images are used to estimate the single-beam uniformity under a variety of conditions including with a distributed phase plate and two-dimensional smoothing by spectral dispersion. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

Smalyuk, V. A.; Boehly, T. R.; Delettrez, J. A.; Iwan, L. S.; Kessler, T. J.; Knauer, J. P.; Marshall, F. J.; Meyerhofer, D. D.

1996-11-01

198

Nonequilibrium electron dynamics in materials driven by high-intensity x-ray pulses  

NASA Astrophysics Data System (ADS)

We calculated the evolution of the electron system in solid-density matter irradiated by high-intensity x-ray pulses between 2 and 8 keV using molecular dynamics. For pulses shorter than 40 fs, the kinetic energy distribution of the electrons is highly nonthermal during and right after the pulse, and a large fraction of the absorbed x-ray energy resides with the fast photoelectrons which equilibrate on the timescale of the pulse length. The average ionization and electron temperature of the bulk of the electrons are significantly lower than their equilibrium values.

Hau-Riege, Stefan P.

2013-05-01

199

Method for beam hardening correction in quantitative computed X-ray tomography  

NASA Technical Reports Server (NTRS)

Each voxel is assumed to contain exactly two distinct materials, with the volume fraction of each material being iteratively calculated. According to the method, the spectrum of the X-ray beam must be known, and the attenuation spectra of the materials in the object must be known, and be monotonically decreasing with increasing X-ray photon energy. Then, a volume fraction is estimated for the voxel, and the spectrum is iteratively calculated.

Yan, Chye Hwang (Inventor); Whalen, Robert T. (Inventor); Napel, Sandy (Inventor)

2001-01-01

200

Comparison of the Effect of X-ray and Electron Beam Irradiation on Some Selected Spices  

Microsoft Academic Search

The effect of irradiation with X-rays and electron beams on the microbiological quality of white pepper, sweet red paprika and nutmeg was examined. Statistical analyses were performed on the data to interpret the results on coliforms, total mesophilic counts and thermophilic spores after irradiation with doses ranging from 0 to 10 kGy at different dose rates, 50 Gy\\/min for X-rays

Sabine Van Calenberg; Gauthier Vanhaelewyn; Oswald Van Cleemput; Freddy Callens; Wim Mondelaers; André Huyghebaert

1998-01-01

201

High Gain, Fast Scan, Broad Spectrum, Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM  

SciTech Connect

Parallax Research, Inc. proposes to produce a new type of x-ray spectrometer for use with Scanning Electron Microscopy (SEM) that would have the energy resolution of WDS and the ease of use of EDS with sufficient gain for lower energies that it can be used at low beam currents as is EDS. Parallax proposes to do this by development of new multiple reflection x-ray collimation optics, new diffractor technology, new detector technology and new scan algorithms.

David OHara; Dr. Eric Lochmer

2003-09-12

202

Statistical Beam-Hardening Correction for Industrial X-ray Computed Tomography  

Microsoft Academic Search

We present an industrial X-ray computed tomograph (CT) system used as an integrated dimensional inspection and non-destructive evaluation tool. The Beam-Hardening (BH) effect inherent to the use of polyenergetic X-ray source is one of major source of artefacts for materials of high atomic number. We present a statistical correction method relying on the histogram analysis of a first uncorrected image.

Raphaël THIERRY; Alexander FLISCH; Alice MICELI

2006-01-01

203

Deep inner-shell multiphoton ionization by intense x-ray free-electron laser pulses.  

PubMed

We have investigated multiphoton multiple ionization dynamics of xenon atoms using a new x-ray free-electron laser facility, SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan, and identified that Xe(n+) with n up to 26 is produced at a photon energy of 5.5 keV. The observed high charge states (n?24) are produced via five-photon absorption, evidencing the occurrence of multiphoton absorption involving deep inner shells. A newly developed theoretical model, which shows good agreement with the experiment, elucidates the complex pathways of sequential electronic decay cascades accessible in heavy atoms. The present study of heavy-atom ionization dynamics in high-intensity hard-x-ray pulses makes a step forward towards molecular structure determination with x-ray free-electron lasers. PMID:23679721

Fukuzawa, H; Son, S-K; Motomura, K; Mondal, S; Nagaya, K; Wada, S; Liu, X-J; Feifel, R; Tachibana, T; Ito, Y; Kimura, M; Sakai, T; Matsunami, K; Hayashita, H; Kajikawa, J; Johnsson, P; Siano, M; Kukk, E; Rudek, B; Erk, B; Foucar, L; Robert, E; Miron, C; Tono, K; Inubushi, Y; Hatsui, T; Yabashi, M; Yao, M; Santra, R; Ueda, K

2013-04-26

204

Application of a transmission crystal x-ray spectrometer to moderate-intensity laser driven sources  

SciTech Connect

In the pursuit of novel, laser-produced x-ray sources for medical imaging applications, appropriate instrumental diagnostics need to be developed concurrently. A type of transmission crystal spectroscopy has previously been demonstrated as a survey tool for sources produced by high-power and high-energy lasers. The present work demonstrates the extension of this method into the study of medium-intensity laser driven hard x-ray sources with a design that preserves resolving power while maintaining high sensitivity. Specifically, spectroscopic measurements of characteristic K{alpha} and K{beta} emissions were studied from Mo targets irradiated by a 100 fs, 200 mJ, Ti: sapphire laser with intensity of 10{sup 17} W/cm{sup 2} to 10{sup 18} W/cm{sup 2} per shot. Using a transmission curved crystal spectrometer and off-Rowland circle imaging, resolving powers (E/{Delta}E) of around 300 for Mo K{alpha}{sub 2} at 17.37 keV were obtained with an end-to-end spectrometer efficiency of (1.13 {+-} 0.10) x 10{sup -5}. This sensitivity is sufficient for registering x-ray lines with high signal to background from targets following irradiation by a single laser pulse, demonstrating the utility of this method in the study of the development of medium-intensity laser driven x-ray sources.

Mao, J. Y.; Chen, L. M.; Zhang, L.; Sun, Y. Q.; Lin, X. X. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China); Hudson, L. T. [National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, Maryland 20899 (United States); Seely, J. F. [Space Science Division, Naval Research Laboratory, Washington, District of Columbia 20375 (United States); Zhang, J. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100190 (China); Department of Physics, Shanghai Jiao tong University, Shanghai 200240 (China)

2012-04-15

205

Application of a transmission crystal x-ray spectrometer to moderate-intensity laser driven sources.  

PubMed

In the pursuit of novel, laser-produced x-ray sources for medical imaging applications, appropriate instrumental diagnostics need to be developed concurrently. A type of transmission crystal spectroscopy has previously been demonstrated as a survey tool for sources produced by high-power and high-energy lasers. The present work demonstrates the extension of this method into the study of medium-intensity laser driven hard x-ray sources with a design that preserves resolving power while maintaining high sensitivity. Specifically, spectroscopic measurements of characteristic K? and K? emissions were studied from Mo targets irradiated by a 100 fs, 200 mJ, Ti: sapphire laser with intensity of 10(17) W/cm(2) to 10(18) W?cm(2) per shot. Using a transmission curved crystal spectrometer and off-Rowland circle imaging, resolving powers (E/?E) of around 300 for Mo K?(2) at 17.37 keV were obtained with an end-to-end spectrometer efficiency of (1.13 ± 0.10) × 10(-5). This sensitivity is sufficient for registering x-ray lines with high signal to background from targets following irradiation by a single laser pulse, demonstrating the utility of this method in the study of the development of medium-intensity laser driven x-ray sources. PMID:22559512

Mao, J Y; Chen, L M; Hudson, L T; Seely, J F; Zhang, L; Sun, Y Q; Lin, X X; Zhang, J

2012-04-01

206

Transverse Coherence of the LCLS X-Ray Beam  

SciTech Connect

Self-amplifying spontaneous radiation free-electron lasers, such as the LCLS or the European X-FEL, rely on the incoherent, spontaneous radiation as the seed for the amplifying process. Though this method overcomes the need for an external seed source one drawback is the incoherence of the effective seed signal. The FEL process allows for a natural growth of the coherence because the radiation phase information is spread out within the bunch due to slippage and diffraction of the radiation field. However, at short wavelengths this spreading is not sufficient to achieve complete coherence. In this presentation we report on the results of numerical simulations of the LCLS X-ray FEL. From the obtained radiation field distribution the coherence properties are extracted to help to characterize the FEL as a light source.

Not Available

2010-12-01

207

Transverse Coherence Properties of the LCLS X-Ray Beam  

SciTech Connect

Self-amplifying spontaneous radiation free-electron lasers, such as the LCLS or the European X-FEL, rely on the incoherent, spontaneous radiation as the seed for the amplifying process. Though this method overcomes the need for an external seed source one drawback is the incoherence of the effective seed signal. The FEL process allows for a natural growth of the coherence because the radiation phase information is spread out within the bunch due to slippage and diffraction of the radiation field. However, at short wavelengths this spreading is not sufficient to achieve complete coherence. In this presentation we report on the results of numerical simulations of the LCLS X-ray FEL. From the obtained radiation field distribution the coherence properties are extracted to help to characterize the FEL as a light source.

Reiche, S.; /UCLA

2007-04-16

208

Intensities of X-Rays and gamma Rays in Am241 Alpha Decay  

Microsoft Academic Search

Electromagnetic radiation intensities from levels of Np237 were remeasured with NaI scintillation detectors and an argon proportional chamber. By absolute and coincidence counting the photon intensities per alpha particle are 0.376, 0.025, 0.00073, and 0.359 for the L x-rays and the 26.4-, 43.4-, and 59.6-kev gamma rays, respectively. Gamma rays with 99- and 103-kev energy were found by alpha-gamma coincidence.

L. B. Magnusson

1957-01-01

209

Quasi-monoenergetic proton beams by laser-plasma X-rays  

NASA Astrophysics Data System (ADS)

We report the details of a technique for the production of proton beams with very low energy spread exploiting the short soft X-rays obtained by laser ablation. These beams have been generated by the dissociation and ionization of an hydrogen buffer gas induced by the laser-plasma X-rays and then accelerated by means of an electrostatic accelerator. Their properties have been analyzed through the time-of-flight method applying different accelerating voltages. The resulting energetic spread ranges between 6 and 11%, as a function of the applied voltage. Such a system could be extremely useful for producing quasi-monoenergetic proton beams.

Delle Side, D.; Krása, J.; Nassisi, V.; Velardi, L.

2014-04-01

210

Radiation damage in protein crystals is reduced with a micron-sized X-ray beam  

PubMed Central

Radiation damage is a major limitation in crystallography of biological macromolecules, even for cryocooled samples, and is particularly acute in microdiffraction. For the X-ray energies most commonly used for protein crystallography at synchrotron sources, photoelectrons are the predominant source of radiation damage. If the beam size is small relative to the photoelectron path length, then the photoelectron may escape the beam footprint, resulting in less damage in the illuminated volume. Thus, it may be possible to exploit this phenomenon to reduce radiation-induced damage during data measurement for techniques such as diffraction, spectroscopy, and imaging that use X-rays to probe both crystalline and noncrystalline biological samples. In a systematic and direct experimental demonstration of reduced radiation damage in protein crystals with small beams, damage was measured as a function of micron-sized X-ray beams of decreasing dimensions. The damage rate normalized for dose was reduced by a factor of three from the largest (15.6 ?m) to the smallest (0.84 ?m) X-ray beam used. Radiation-induced damage to protein crystals was also mapped parallel and perpendicular to the polarization direction of an incident 1-?m X-ray beam. Damage was greatest at the beam center and decreased monotonically to zero at a distance of about 4 ?m, establishing the range of photoelectrons. The observed damage is less anisotropic than photoelectron emission probability, consistent with photoelectron trajectory simulations. These experimental results provide the basis for data collection protocols to mitigate with micron-sized X-ray beams the effects of radiation damage.

Sanishvili, Ruslan; Yoder, Derek W.; Pothineni, Sudhir Babu; Rosenbaum, Gerd; Xu, Shenglan; Vogt, Stefan; Stepanov, Sergey; Makarov, Oleg A.; Corcoran, Stephen; Benn, Richard; Nagarajan, Venugopalan; Smith, Janet L.; Fischetti, Robert F.

2011-01-01

211

Wide-angle monochromatic x-ray beam shutter : a design study..  

National Technical Information Service (NTIS)

A novel design of a wide-angle monochromatic x-ray beam shutter is discussed. The shutter is designed as a compact unit capable of providing users with the means of shutting off the beam in secondary beamlines that are at an angle to the primary beamline ...

B. Brajuskovic J. Chang F. Carrera L. Lourio J. F. Pelletier D. Shu

2002-01-01

212

Intense X-ray FEL-molecule physics: Highly charged ions  

SciTech Connect

We report on sequential multiphoton ionization of N{sub 2}, H{sub 2}S and SF{sub 6} by intense, femtosecond duration pulses of x-rays from the LCLS free electron laser. Following either K- or L-shell excitation, we observe ionization and fragmentation of the molecule by Auger electron, photoelectron, and ion time-of-flight spectroscopy. Intense excitation of the K-shell leads to depletion and double core hole effects, observed in N{sub 2}. For L-shell excitation, additional relaxation channels suppress depletion, allowing ionization to continue until energetically forbidden. The investigation of multiphoton ionization has produced a better understanding of molecular plasmas created by intense ultrafast x-ray exposure.

Murphy, B. F.; Fang, L.; Osipov, T. Y.; Hoener, M.; Berrah, N. [Western Michigan University, Physics Department, 1903 W. Michigan Avenue, Kalamazoo, MI, 49008 (United States)

2012-05-25

213

Intense X-ray FEL-molecule physics: Highly charged ions  

NASA Astrophysics Data System (ADS)

We report on sequential multiphoton ionization of N2, H2S and SF6 by intense, femtosecond duration pulses of x-rays from the LCLS free electron laser. Following either K- or L-shell excitation, we observe ionization and fragmentation of the molecule by Auger electron, photoelectron, and ion time-of-flight spectroscopy. Intense excitation of the K-shell leads to depletion and double core hole effects, observed in N2 [1, 2]. For L-shell excitation, additional relaxation channels suppress depletion, allowing ionization to continue until energetically forbidden. The investigation of multiphoton ionization has produced a better understanding of molecular plasmas created by intense ultrafast x-ray exposure.

Murphy, B. F.; Fang, L.; Osipov, T. Y.; Hoener, M.; Berrah, N.

2012-05-01

214

Computational simulations of high-intensity x-ray matter interaction  

NASA Astrophysics Data System (ADS)

Free electron lasers have the promise of producing extremely high-intensity short pulses of coherent, monochromatic radiation in the 1-10 keV energy range. For example, the Linac Coherent Light Source at Stanford is being designed to produce an output intensity of 2x1014 W/cm2 in a 230 fs pulse. These sources will open the door to many novel research studies. However, the intense x-ray pulses may damage the optical components necessary for studying and controlling the output. At the full output intensity, the dose to optical components at normal incidence ranges from 1-10 eV/atom for low-Z materials (Z<14) at photon energies of 1 keV. It is important to have an understanding of the effects of such high doses in order to specify the composition, placement, and orientation of optical components, such as mirrors and monochromators. Doses of 10 eV/atom are certainly unacceptable since they will lead to ablation of the surface of the optical components. However, it is not precisely known what the damage thresholds are for the materials being considered for optical components for x-ray free electron lasers. In this paper, we present analytic estimates and computational simulations of the effects of high-intensity x-ray pulses on materials. We outline guidelines for the maximum dose to various materials and discuss implications for the design of optical components.

London, Richard A.; Bionta, Richard M.; Tatchyn, Roman O.; Roesler, S.

2001-12-01

215

Cone-beam differential phase-contrast laminography with x-ray tube source  

NASA Astrophysics Data System (ADS)

We report on an x-ray cone-beam differential phase-contrast computed laminography (DPC-CL) method for tomographic reconstruction of thin and lamellar objects. We describe the specific scan geometry of DPC-CL, which consists of a Talbot-Lau grating interferometer and a lab-based x-ray tube source, and derive a filtered back-projection (FBP) reconstruction algorithm. The experimental results of a flat sphere phantom and a piece of ham demonstrate the validity of the proposed technique. The existing DPC-CL methods are based on synchrotron sources and the parallel-beam geometry. In contrast, our approach adopts a more accessible x-ray tube source and a cone-beam geometry. Therefore it significantly widens the application range of phase-contrast laminography, particularly in practical laboratory settings, beyond applications at large-scale synchrotron facilities.

Fu, J.; Biernath, T.; Willner, M.; Amberger, M.; Meiser, J.; Kunka, D.; Mohr, J.; Herzen, J.; Bech, M.; Pfeiffer, F.

2014-06-01

216

Time-delayed beam splitting with energy separation of x-ray channels  

SciTech Connect

We introduce a time-delayed beam splitting method based on the energy separation of x-ray photon beams. It is implemented and theoretically substantiated on an example of an x-ray optical scheme similar to that of the classical Michelson interferometer. The splitter/mixer uses Bragg-case diffraction from a thin diamond crystal. Another two diamond crystals are used as back-reflectors. Because of energy separation and a minimal number (three) of optical elements, the split-delay line has high efficiency and is simple to operate. Due to the high transparency of diamond crystal, the split-delay line can be used in a beam sharing mode at x-ray free-electron laser facilities.

Stetsko, Yuri P.; Shvyd'ko, Yuri V.; Brian Stephenson, G. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2013-10-21

217

A simple analytical expression to calculate the backscatter factor for low energy X-ray beams.  

PubMed

A simple analytical expression aiming to calculate the backscatter factor used in dosimetry protocols to determine the absorbed dose in water for low energy X-rays beams is presented. This expression is based on the linear dependence of the backscatter factor with the generating potential, for fixed values of the half-value layer. The results of a recent work in which 74 X-ray beams with different spectroscopic characteristics, generated with the code (xcomp5r) and transported with the Monte Carlo code (penelope) have been used. The expression derived permits to calculate the backscatter factor within 5% accuracy. The predictive power of this expression has been tested for 20 X-ray beams generated with potentials from 50 to 250 kV, for which half-value layers and backscatter factors have been experimentally determined. PMID:20434382

Chica, U; Flórez, G; Anguiano, M; Lallena, A M

2011-04-01

218

A wide-beam X-ray source suitable for diffraction enhanced imaging applications  

NASA Astrophysics Data System (ADS)

Research in diffraction-enhanced imaging (DEI), using a synchrotron source with an X-ray flux of 1.4×10 12 ph/mm 2/s, has shown strong potential in obtaining high-resolution images as compared to conventional radiographs. This research investigates the feasibility of developing a large area circular X-ray source with fluxes comparable to a synchrotron source. The source should be capable of integration into a compact system with peak powers not to exceed 200 kW to be feasible for use in a major medical facility, industrial complex or screening facility (such as cargo or airport). A computational study of a circular concentric filament wide-beam area X-ray source has been investigated in this research. The design features are based on generating electrons from three concentric circular filaments to provide an area electron flux, with a 60 kV accelerating potential and a beam current of up to 3 A. The X-ray target is a grounded stationary oxygen-free copper target with a layer of molybdenum. This target feature differs from standard rotating X-ray targets in conventional X-ray systems. Studies of electron trajectories and their distribution on the target were conducted using the SIMION 3D code. Heat loading and thermal management were studied using heat transfer modules from the coupled FEMLAB multi-physics and MATLAB codes. The Monte Carlo code MCNP 5 was used to obtain the X-ray flux and energy distribution for aluminum and beryllium windows. This computational study shows that this target configuration generates X-rays with photon flux comparable to synchrotron source and sufficient for DEI applications. The maximum target temperature rise is 1357 K after 70 s when cooling the back of the target to liquid nitrogen temperature using cold finger contact, and 325 K for an invaded target, in which liquid nitrogen circulates inside the target.

Kim, Chang H.; Bourham, Mohamed A.; Michael Doster, J.

2006-10-01

219

Prospects for compact high-intensity laser synchrotron x-ray and gamma sources  

SciTech Connect

A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high-brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power CO{sub 2} laser may be used as prototype LSS brick stones. In a feasible demonstration experiment, 10-GW, 100-ps CO{sub 2} laser beam will be brought to a head-on collision with a 10-ps, 0.5-nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 {angstrom}) x-rays of 10-ps pulse duration, with a flux of {approximately} 10{sup 19} photons/sec, will be produced via linear Compton backscattering. The x-ray spectrum is tunable proportionally to the e-beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 10{sup 22} photons/sec level, after the ongoing ATF CO{sub 2} laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact ``table-top`` LSS of monochromatic gamma radiation may become feasible.

Pogorelsky, I.V. [Brookhaven National Lab., Upton, NY (United States). Accelerator Test Facility

1996-11-01

220

Prospects for compact high-intensity laser synchrotron x-ray and gamma sources  

SciTech Connect

A laser interacting with a relativistic electron beam behaves like a virtual wiggler of an extremely short period equal to half of the laser wavelength. This approach opens a route to relatively compact, high- brightness x-ray sources alternative or complementary to conventional synchrotron light sources. Although not new, the laser synchrotron source (LSS) concept is still waiting for a convincing demonstration. Available at the BNL Accelerator Test Facility (ATF), a high- brightness electron beam and the high-power C0{sub 2} laser may be used as prototype LSS brick stones. In a feasible demonstration experiment, 10 GW, 100 ps C0{sub 2} laser beam will be brought to a head-on collision with a 10 ps, 0.5 nC, 50 MeV electron bunch. Flashes of collimated 4.7 keV (2.6 A) x-rays of 10-ps pulse duration, with a flux of {approximately}10{sup 19} photons/sec, will be produced via linear Compton backscattering. The x-ray spectra is tunable proportionally to the e- beam energy. A rational short-term extension of the proposed experiment would be further enhancement of the x-ray flux to the 10{sup 22} photon/sec level, after the ongoing ATF C0{sub 2} laser upgrade to 5 TW peak power and electron bunch shortening to 3 ps is realized. In the future, exploiting the promising approach of a high-gradient laser wake field accelerator, a compact ``table- top`` LSS of monochromatic gamma radiation may become feasible.

Pogorelsky, I.V.

1997-01-01

221

X-ray reemission from CH foils heated by laser-generated intense thermal radiation  

SciTech Connect

X-ray emission and burn through of radiatively heated plastic foils have been investigated in a gold cavity heated by eight beams of the Gekko XII laser up to a radiation temperature of 140 eV. We measured the temporally resolved reemission spectra of carbon. The time and frequency integrated reemission was 23% of the gold reemission. The measurements are in good agreement with numerical simulations.

Foeldes, I.B.; Eidmann, K.; Loewer, T.; Massen, J.; Sigel, R.; Tsakiris, G.D.; Witkowski, S.; Nishimura, H.; Endo, T.; Shiraga, H.; Takagi, M.; Kato, Y.; Nakai, S. (Max-Planck-Institut fuer Quantenoptik, D-85740 Garching (Germany) Institute of Laser Engineering, Osaka University, Suita, Osaka, 565 (Japan) Institute for Laser Technology, 2-6 Yamada-oka, Suita, Osaka, 565 (Japan))

1994-08-01

222

Precise delineation characteristics for 1×X-ray mask using advanced electron beam mask writer EB-X3  

Microsoft Academic Search

A variable-shaped electron beam (e-beam) mask writer, EB-X3 was developed for 100 nm node 1×X-ray mask fabrication. It features a stable electron column of 100 kV and the address unit of 1 nm. This paper describes delineation characteristics of the EB-X3 on X-ray membrane mask. We have evaluated image placement (IP) accuracy and e-beam proximity effects on the X-ray membrane

S. Tsuboi; H. Watanabe; M. Ezaki; H. Aoyama; Y. Kikuchi; Y. Nakayama; S. Ohki; T. Watanabe; T. Morosawa; K. Saito; M. Oda; T. Matsuda

2000-01-01

223

A preliminary investigation of cell growth after irradiation using a modulated x-ray intensity pattern  

NASA Astrophysics Data System (ADS)

In this study we have investigated a spatial distribution of cell growth after their irradiation using a modulated x-ray intensity pattern. An A549 human non-small cell lung cancer cell line was grown in a 6-well culture. Two of the wells were the unirradiated control wells, whilst another two wells were irradiated with a modulated x-ray intensity pattern and the third two wells were uniformly irradiated. A number of plates were incubated for various times after irradiation and stained with crystal violet. The spatial distribution of the stained cells within each well was determined by measurement of the crystal violet optical density at multiple positions in the plate using a microplate photospectrometer. The crystal violet optical density for a range of cell densities was measured for the unirradiated well and this correlated with cell viability as determined by the MTT cell viability assay. An exponential dose response curve was measured for A549 cells from the average crystal violet optical density in the uniformly irradiated well up to a dose of 30 Gy. By measuring the crystal violet optical density distribution within a well the spatial distribution of cell growth after irradiation with a modulated x-ray intensity pattern can be plotted. This method can be used for in vitro investigation into the changes in radiation response associated with treatment using intensity modulated radiation therapy (IMRT).

Bromley, Regina; Davey, Ross; Oliver, Lyn; Harvie, Rozelle; Baldock, Clive

2006-08-01

224

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy  

SciTech Connect

For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these so-called quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an origin-independent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole and electric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within time-dependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes.

Bernadotte, Stephan; Atkins, Andrew J.; Jacob, Christoph R. [Karlsruhe Institute of Technology (KIT), Center for Functional Nanostructures and Institute of Physical Chemistry, Wolfgang-Gaede-Str. 1a, 76131 Karlsruhe (Germany)

2012-11-28

225

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these so-called quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an origin-independent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole and electric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within time-dependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes.

Bernadotte, Stephan; Atkins, Andrew J.; Jacob, Christoph R.

2012-11-01

226

Observation of the Talbot effect using broadband hard x-ray beam  

SciTech Connect

We demonstrated the Talbot effect using a broadband hard x-ray beam ({Delta}{lambda}/{lambda} {approx}1). The exit wave-field of the x-ray beam passing through a grating with a sub micro-meter scale period was successfully replicated and recorded at effective Talbot distance, Z{sub T}. The period was reduced to half at Z{sub T}/4 and 3/4Z{sub T}, and the phase reversal was observed at Z{sub T}/2. The propagating wave-field recorded on photoresists was consistent with a simulated result.

Kim, J.M.; Conley, R.; Cho, I. H.; Lee, S. Y.; Kang, H. C.; Liu, C.; Macrander, A. T.; Noh, D. Y.

2010-11-15

227

Simulations of High Intensity X-ray Free-Electron Laser Interactions with Matter by use of the SCFLY Code  

NASA Astrophysics Data System (ADS)

The last few years has seen a revolution in FEL technology such that multi-keV X-ray beams with focussed intensities in excess of 10^18 Wcm-2 can routinely be produced. An understanding of how such radiation interacts with matter requires atomic kinetics codes with the capabilities to model large numbers of configurations, the inclusion of exotic (e.g. double core-hole) states, as well as treating the X-ray heating consistently. We report here on the use of a modified version of the SCFLYootnotetextH.-K. Chung, M.H. Chen, W.L. Morgan, Y. Ralchenko, and R.W. Lee, High Energy Density Physics 1, 3, (2005). code to model experiments where the LCLS beam interacted with in a low density Neon gas,ootnotetextL. Young et al, Nature, 466, 56 (2010).^,ootnotetextO. Ciricosta, H.-K. Chung, R.W. Lee, and J.S. Wark, High Energy Density Physics, 7, 111, (2011). as well as more recent work where the LCLS beam was focused onto solid aluminum targets. We further demonstrate that at high photon energies the LCLS beam can be used as a non-perturbative probe of pre-exisiting charge states.

Wark, Justin; Ciricosta, Orlando; Vinko, Sam; Chung, Hyun-Kyung; Lee, Richard

2011-11-01

228

Accounting for low-frequency synchrotron X-ray beam position fluctuations for dynamic visualizations.  

PubMed

Synchrotron X-ray radiography on beamline 05B1-1 at the Canadian Light Source Inc. was employed to study dynamic liquid water transport in the porous electrode materials of polymer electrolyte membrane fuel cells. Dynamic liquid water distributions were quantified for each radiograph in a sequence, and non-physical liquid water measurements were obtained. It was determined that the position of the beam oscillated vertically with an amplitude of ~25 µm at the sample and a frequency of ~50 mHz. In addition, the mean beam position moved linearly in the vertical direction at a rate of 0.74 µm s(-1). No evidence of horizontal oscillations was detected. In this work a technique is presented to account for the temporal and spatial dependence of synchrotron beam intensity, which resulted in a significant reduction in false water thickness. This work provides valuable insight into the treatment of radiographic time-series for capturing dynamic processes from synchrotron radiation. PMID:23093760

Hinebaugh, J; Challa, P R; Bazylak, A

2012-11-01

229

Cone beam x-ray luminescence computed tomography: A feasibility study  

SciTech Connect

Purpose: The appearance of x-ray luminescence computed tomography (XLCT) opens new possibilities to perform molecular imaging by x ray. In the previous XLCT system, the sample was irradiated by a sequence of narrow x-ray beams and the x-ray luminescence was measured by a highly sensitive charge coupled device (CCD) camera. This resulted in a relatively long sampling time and relatively low utilization of the x-ray beam. In this paper, a novel cone beam x-ray luminescence computed tomography strategy is proposed, which can fully utilize the x-ray dose and shorten the scanning time. The imaging model and reconstruction method are described. The validity of the imaging strategy has been studied in this paper. Methods: In the cone beam XLCT system, the cone beam x ray was adopted to illuminate the sample and a highly sensitive CCD camera was utilized to acquire luminescent photons emitted from the sample. Photons scattering in biological tissues makes it an ill-posed problem to reconstruct the 3D distribution of the x-ray luminescent sample in the cone beam XLCT. In order to overcome this issue, the authors used the diffusion approximation model to describe the photon propagation in tissues, and employed the sparse regularization method for reconstruction. An incomplete variables truncated conjugate gradient method and permissible region strategy were used for reconstruction. Meanwhile, traditional x-ray CT imaging could also be performed in this system. The x-ray attenuation effect has been considered in their imaging model, which is helpful in improving the reconstruction accuracy. Results: First, simulation experiments with cylinder phantoms were carried out to illustrate the validity of the proposed compensated method. The experimental results showed that the location error of the compensated algorithm was smaller than that of the uncompensated method. The permissible region strategy was applied and reduced the reconstruction error to less than 2 mm. The robustness and stability were then evaluated from different view numbers, different regularization parameters, different measurement noise levels, and optical parameters mismatch. The reconstruction results showed that the settings had a small effect on the reconstruction. The nonhomogeneous phantom simulation was also carried out to simulate a more complex experimental situation and evaluated their proposed method. Second, the physical cylinder phantom experiments further showed similar results in their prototype XLCT system. With the discussion of the above experiments, it was shown that the proposed method is feasible to the general case and actual experiments. Conclusions: Utilizing numerical simulation and physical experiments, the authors demonstrated the validity of the new cone beam XLCT method. Furthermore, compared with the previous narrow beam XLCT, the cone beam XLCT could more fully utilize the x-ray dose and the scanning time would be shortened greatly. The study of both simulation experiments and physical phantom experiments indicated that the proposed method was feasible to the general case and actual experiments.

Chen Dongmei; Zhu Shouping; Yi Huangjian; Zhang Xianghan; Chen Duofang; Liang Jimin [School of Life Sciences and Technology, Xidian University, Xi'an 710071 (China); Tian Jie [School of Life Sciences and Technology, Xidian University, Xi'an 710071 (China); Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, Beijing 100190 (China)

2013-03-15

230

Neutron dosimetry in high energy X-ray beams of medical accelerators  

Microsoft Academic Search

High energy X-ray beams from medical accelerators are used in cancer therapy. In such beams, neutrons are also produced due to photon-neutron interactions in the target materials, collimator and beam flattening filter. The feasibility of employing fast-neutron-induced recoil particle tracks in polycarbonate foils developed by the electrochemical etching (ECE) method for the dosimetry of such neutrons was investigated. The experiments

M. Sohrabi; K. Z. Morgan

1979-01-01

231

Flash X-Ray (FXR) Accelerator Optimization Beam-Induced Voltage Simulation and TDR Measurements  

Microsoft Academic Search

Lawrence Livermore National Laboratory (LLNL) is evaluating design alternatives to improve the voltage regulation in our Flash X-Ray (FXR) accelerator cell and pulse-power system. The goal is to create a more mono-energetic electron beam. When an electron beam crosses the energized gap of an accelerator cell, the electron energy is increased. However, the beam with the associated electromagnetic wave also

M. M. Ong; G. E. Vogtlin

2005-01-01

232

Description of the dependence of intensity of x-ray fluorescence on the particle size of powder samples and pulp during x-ray fluorescent analysis  

Microsoft Academic Search

The dependence of intensity of x-ray fluorescence on particle size for powdered and pulplike media is described using a general\\u000a analytical expression. The expression is obtained for a model of a powder medium consisting of particles of various sizes\\u000a distributed randomly in the sample bulk. This expression involves expressions for the fluorescence intensity for homogeneous\\u000a and pulplike media as limiting

A. L. Finkel’shtein; T. N. Gunicheva

2008-01-01

233

Characteristics of a contract electron beam and bremsstrahlung (X-ray) irradiation facility of Radia industry  

NASA Astrophysics Data System (ADS)

A contract electron beam(EB) and bremsstrahlung(X-ray) facility with use of NHV 5 MeV, 30 mA Cock-Croft Walton machine is operational for EB since April 1991, and X-ray commercial irradiation was started in 1992 summer. The facility is consisted of the EB machine, bremsstrahlung target, chain and roller conveyor, and automatic turnover machine for dual sided irradiation. The operation of the system is fully controlled by LAN of personal computers for client's order, EB characteristics, beam current control proportional to the conveyor speed, turnover of product in processing mid point, and output of processing record to clients. The control and recording systems avoid human errors. This paper mainly discusses X-ray processing.

Takehisa, Masaaki; Saito, Toshio; Takahashi, Thoru; Sato, Yoshishige; Sato, Toshio

1993-07-01

234

Inclined-incidence quasi-Fresnel lens for prefocusing of synchrotron radiation x-ray beams  

NASA Astrophysics Data System (ADS)

An inclined-incidence quasi-Fresnel lens made of acrylic resin has been developed for prefocusing in synchrotron radiation x-ray beamlines. By inclining the lens, the grating aspect ratio is large enough for x-ray use. As it operates in transmission mode with negligible beam deflection and offset, little additional equipment is needed to introduce it into existing beamlines. It is fabricated by sheet-press forming, enabling inexpensive mass production. The prototype was able to focus a 730-?m-wide beam to a width of 80 ?m with a photon flux density gain of 5.6 at an x-ray energy of 10 keV.

Kagoshima, Yasushi; Takano, Hidekazu; Takeda, Shingo

2012-10-01

235

Generation of Attosecond X-ray Pulses Beyond the Atomic Unit of Time Using Laser Induced Microbunching in Electron Beams  

SciTech Connect

Ever since the discovery of mode-locking, efforts have been devoted to reducing the duration of laser pulses since the ultrashort pulses are critical to explore the dynamics occurred on a ever-shorter timescale. In this paper we describe a scheme that's capable of generating intense attosecond x-ray pulses with duration beyond the atomic unit of time ({approx}24 attoseconds). The scheme combines the echo-enabled harmonic generation technique with the bunch compression which allows one to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of a UV seed laser. A few-cycle intense IR laser is used to generate the required energy chirp in the beam for bunch compression and for selection of an attosecond x-ray pulse. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power of a few hundred MW and duration as short as 20 attoseconds (FWHM) can be generated from a 200 nm UV seed laser. The proposed scheme may enable the study of electronic dynamics with a resolution beyond the atomic unit of time and may open a new regime of ultrafast sciences.

Xiang, D.; Huang, Z.; Stupakov, G.; /SLAC

2009-12-11

236

Electron Beam Production, Transport, and Final Focus for the PLEIADES Thomson X-ray Source  

NASA Astrophysics Data System (ADS)

The small interaction area required for Thomson x-ray sources necessitates the production of high brightness electron beams and the use of very strong final focus optics. We report on the details of the electron beam production, transport and final focus for the PLEIADES Thomson X-ray Source at Lawrence Livermore National Laboratory, including the S-band RF photocathode electron gun and 100 MeV S-Band accelerator, as well as the beam diagnostics and final focus optics. According to simulations, a beam emittance ranging from 2 to 5 mm-mrad is obtainable for bunch charges ranging from 0.5 to 1.0 nC, with an obtainable final focus spot size as low as 15 micro-meters rms for these beam parameters. The x-ray source is expected to produced pico-second xray pulses of brightness 1020 photons/0.1% bandwidth/mm^2/mrad^2 by colliding a 20 micro-meter, 0.5-1.0 nC, 0.5-5 ps electron bunch with a 100 fs, 300 mJ, 800 nm laser pulse. Measurements of the electron beam parameters and x-ray production will also be reported and compared to the theoretical expectations. In addition, the possibility of improving the electron beam focus and ultimate x-ray source brightness by implementing the use of stronger final focus optics will be discussed. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Brown, Winthrop J.; Anderson, Scott G.; Barty, Chris P.; Crane, John K.; Cross, Rick R.; Fittinghoff, Dave N.; Hartemann, Fred V.; Kuba, Jaroslav; Lesage, Greg P.; Slaughter, Dennis R.; Springer, Paul T.; Tremaine, Aaron M.; Gibson, David J.; Rosenzweig, James B.

2003-10-01

237

Femtosecond time-resolved X-ray absorption spectroscopy of liquid using a hard X-ray free electron laser in a dual-beam dispersive detection method.  

PubMed

We present femtosecond time-resolved X-ray absorption spectroscopy of aqueous solution using a hard x-ray free electron laser (SACLA) and a synchronized Ti:sapphire laser. The instrumental response time is 200 fs, and the repetition rate of measurement is 10 Hz. A cylindrical liquid beam 100 ?m in diameter of aqueous ammonium iron(III) oxalate solution is photoexcited at 400 nm, and the transient X-ray absorption spectra are measured in the K-edge region of iron, 7.10 - 7.26 keV, using a dual X-ray beam dispersive detection method. Each of the dual beams has the pulse energy of 1.4 ?J, and pump-induced absorbance change on the order of 10(-3) is successfully detected. The photoexcited iron complex exhibits a red shifted iron K-edge with the appearance time constant of 260 fs. The X-ray absorption difference spectra, with and without the pump pulses, are independent of time delay after 1.5 ps up to 100 ps, indicating that the photoexcited species is long-lived. PMID:24515070

Obara, Yuki; Katayama, Tetsuo; Ogi, Yoshihiro; Suzuki, Takayuki; Kurahashi, Naoya; Karashima, Shutaro; Chiba, Yuhei; Isokawa, Yusuke; Togashi, Tadashi; Inubushi, Yuichi; Yabashi, Makina; Suzuki, Toshinori; Misawa, Kazuhiko

2014-01-13

238

Ion beam profiling of aspherical X-ray mirrors  

NASA Astrophysics Data System (ADS)

We present a fast and robust ion beam etching technique to profile initially flat surfaces into aspherical ones. The surfacing method is based on the displacement at variable speed of a double-blade system placed between a broad ion beam source and a mirror, thus allowing a spatial modulation of the ion dose along the mirror surface. The fabrication process was validated using various metrology techniques to assess both mirror figure and finish. The method was successfully applied to produce two strongly elliptically shaped mirror prototypes (source-mirror distance 150 m and demagnification 3000). The residual slope errors were found to be 18 ?rad over a mirror length of 40 mm while the root mean squared roughness remains below 0.2 nm for spatial periods less than 130 ?m.

Peverini, L.; Kozhevnikov, I. V.; Rommeveaux, A.; Vaerenbergh, P. V.; Claustre, L.; Guillet, S.; Massonnat, J.-Y.; Ziegler, E.; Susini, J.

2010-05-01

239

Radiation beam therapy evolution: From X-rays to hadrons  

SciTech Connect

The history of external radiation beam therapy (radiotherapy)-in particular, proton therapy (PT)-is brietly outlined. Two possible strategies in increasing the efficacy of radiotherapy are considered. The radiotherapy methods and techniques are brietly described. The possibilities of PT in providing effective treatment and the main achievements are demonstrated. The state of the art in the PT development involving the active creation of large clinical PT centers since 1990 is analyzed.

Khoroshkov, V. S. [Institute of Theoretical and Experimental Physics (Russian Federation)], E-mail: khoroshkov@itep.ru

2006-10-15

240

Characterization of Laser-Driven Electron Beams for Thomson X-Ray Sources  

NASA Astrophysics Data System (ADS)

The relativistic nonlinear motions of a free electron resulting from extreme intensity light fields results in harmonic generation, referred to as nonlinear Thomson scattering. Up to the 30th harmonic has been observed experimentally, and the role of energetic electrons has been inferred from the narrow angular spread of the scattered light[1]. Both experiment and theory lead us to the conclusion that the electron beam emittance, flux, and energy are critical factors. Here we report on recent studies to accurately characterize and improve the laser produced electron beam. The relationship of the gas delivery conditions is first investigated by interferometric characterization of gas output from both optimized supersonic nozzles[2] and typical nozzles utilized in past experiments at Michigan. These nozzles are then compared with respect to quality of electron beam generation. Electron beam emittance is measured using the pepperpot technique, and the charge is quantified non-perturbatively by utilizing an integrating current transformer. Aluminum and mylar filters allow us to examine emittance and flux for various components of the electron spectrum. These details of the scattering electron beam are critical considerations for the creation of an all-optical, short pulse, and high-spatial-coherence source of x-rays for time resolved diffraction and absorption studies. Work supported by the Chemical Sciences, Geosciences and Biosciences Division of the Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy and NSF Grants 0078581 and 0114336. [1] S. Banerjee, A. Valenzuela, R. Shah, A Maksimchuk, and D. Umstadter, Phys. Plasmas 9, 2392 (2002). [2] S. Semushin and V. Malka, Rev. of Sci. Inst. 72, 2961 (2001).

Shah, Rahul; Korbiak, Katherine; Valenzuela, Anthony; Banerjee, Sudeep; Umstadter, Donald

2002-11-01

241

X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)  

SciTech Connect

An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab.

Marrs, R.E.; Bennett, C.; Chen, M.H.; Cowan, T.; Dietrich, D.; Henderson, J.R.; Knapp, D.A.; Levine, M.A.; Schneider, M.B.; Scofield, J.H.

1988-01-01

242

X-ray spectra from the Cornell Electron-Beam Ion Source (CEBIS I)  

SciTech Connect

Radiation emitted from the Cornell electron beam ion source (CEBIS I) has been surveyed with a Si(Li) x-ray detector. These spectra can be used to estimate backgrounds from electron bremsstrahlung and to evaluate the feasibility of atomic physics experiments using the CEBIS I source in this configuration. 1 ref., 2 figs.

Johnson, B.M.; Jones, K.W.; Kostroun, V.O.; Ghanbari, E.; Janson, S.W.

1985-01-01

243

Narrow-beam x-ray tests of CCD edge response.  

SciTech Connect

The physical boundaries of a fully-depleted charged-coupled device (CCD) can lead to distorted field lines and non-uniform response. We study this response with a beam of X-rays constrained to a width of less than one pixel, and a system to map the CCD response as a function of transverse position.

Kuhlmann, S.; Spinka, H.; Bernstein, J. P.; Beyer, K. A.; Gades, L.; Kasprzyk, T. E.; Miceli, A.; Spence, R. A.; Talaga, R. (High Energy Physics); ( XSD)

2011-04-01

244

Solar Electron Beams Detected in Hard X-Rays and Radio Waves  

Microsoft Academic Search

We present a statistical survey of electron beam signatures that are detected simultaneously at hard X-ray (HXR) and radio wavelengths during solar flares. For the identification of a simultaneous event we require a type III (normal-drifting or reverse-slope-drifting) radio burst that coincides (within ± 1 s) with a significant (>= 3 sigma HXR pulse of similar duration (>= 1 s).

Markus J. Aschwanden; Arnold O. Benz; Brian R. Dennis; Richard A. Schwartz

1995-01-01

245

High Gain, Fast Scan, Broad Spectrum, Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM  

Microsoft Academic Search

Parallax Research, Inc. proposes to produce a new type of x-ray spectrometer for use with Scanning Electron Microscopy (SEM) that would have the energy resolution of WDS and the ease of use of EDS with sufficient gain for lower energies that it can be used at low beam currents as is EDS. Parallax proposes to do this by development of

David OHara; Eric Lochmer

2003-01-01

246

Correction for beam attenuation and indirect excitation in x-ray fluorescence holography  

NASA Astrophysics Data System (ADS)

The influence of beam attenuation (BA) and indirect excitation (IE) processes on atomic resolved imaging with x-ray fluorescence holography (XFH) is considered. It is shown that these processes can influence element sensitivity, the key feature of XFH. A model which allows one to correct for BA and IE is proposed and verified experimentally.

Dul, D. T.; Dabrowski, K. M.; Korecki, P.

2013-12-01

247

Beam Dynamics Study of X-and Linac Driven X-Ray FELS.  

National Technical Information Service (NTIS)

Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band...

C. Adolphsen C. Limborg-Deprey J. Wu T. Raubenheimer Y. P. Sun

2012-01-01

248

Chemically assisted focused-ion-beam etching for tungsten x-ray mask repair  

Microsoft Academic Search

Finely focused ion beams have been used for repair of defects in photomasks and X-ray masks either by sputter removal of excess absorber material or by deposition of new absorber material. These mask structures employ polycrystalline metal absorbers with grain sizes in the 0.1 micrometers range. As feature dimensions are pushed downward, the effects of these grains become more important.

Lloyd R. Harriott; R. R. Kola; George K. Celler

1993-01-01

249

A simple analytical expression to calculate the backscatter factor for low energy X-ray beams  

Microsoft Academic Search

A simple analytical expression aiming to calculate the backscatter factor used in dosimetry protocols to determine the absorbed dose in water for low energy X-rays beams is presented. This expression is based on the linear dependence of the backscatter factor with the generating potential, for fixed values of the half-value layer. The results of a recent work in which 74

U. Chica; G. Flórez; M. Anguiano; A. M. Lallena

2011-01-01

250

THE X-RAY DETECTABILITY OF ELECTRON BEAMS ESCAPING FROM THE SUN  

SciTech Connect

We study the detectability and characterization of electron beams as they leave their acceleration site in the low corona toward interplanetary space through their nonthermal X-ray bremsstrahlung emission. We demonstrate that the largest interplanetary electron beams ({approx}>10{sup 35} electrons above 10 keV) can be detected in X-rays with current and future instrumentation, such as RHESSI or the X-Ray Telescope (XRT) onboard Hinode. We make a list of optimal observing conditions and beam characteristics. Amongst others, good imaging (as opposed to mere localization or detection in spatially integrated data) is required for proper characterization, putting the requirement on the number of escaping electrons (above 10 keV) to {approx}>3 x 10{sup 36} for RHESSI, {approx}>3 x 10{sup 35} for Hinode/XRT, and {approx}>10{sup 33} electrons for the FOXSI sounding rocket scheduled to fly in 2011. Moreover, we have found that simple modeling hints at the possibility that coronal soft X-ray jets could be the result of local heating by propagating electron beams.

Saint-Hilaire, Pascal; Krucker, Saem; Christe, Steven; Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)], E-mail: shilaire@ssl.berkeley.edu

2009-05-01

251

X-ray diffraction imaging of metal-oxide epitaxial tunnel junctions made by optical lithography: use of focused and unfocused X-ray beams.  

PubMed

X-ray diffraction techniques are used in imaging mode in order to characterize micrometre-sized objects. The samples used as models are metal-oxide tunnel junctions made by optical lithography, with lateral sizes ranging from 150 µm down to 10 µm and various shapes: discs, squares and rectangles. Two approaches are described and compared, both using diffraction contrast: full-field imaging (topography) and raster imaging (scanning probe) using a micrometre-sized focused X-ray beam. It is shown that the full-field image gives access to macroscopic distortions (e.g. sample bending), while the local distortions, at the micrometre scale (e.g. tilts of the crystalline planes in the vicinity of the junction edges), can be accurately characterized only using focused X-ray beams. These local defects are dependent on the junction shape and larger by one order of magnitude than the macroscopic curvature of the sample. PMID:23412494

Mocuta, Cristian; Barbier, Antoine; Stanescu, Stefan; Matzen, Sylvia; Moussy, Jean Baptiste; Ziegler, Eric

2013-03-01

252

X-ray diffraction imaging of metal-oxide epitaxial tunnel junctions made by optical lithography: use of focused and unfocused X-ray beams  

PubMed Central

X-ray diffraction techniques are used in imaging mode in order to characterize micrometre-sized objects. The samples used as models are metal–oxide tunnel junctions made by optical lithography, with lateral sizes ranging from 150?µm down to 10?µm and various shapes: discs, squares and rectangles. Two approaches are described and compared, both using diffraction contrast: full-field imaging (topography) and raster imaging (scanning probe) using a micrometre-sized focused X-ray beam. It is shown that the full-field image gives access to macroscopic distortions (e.g. sample bending), while the local distortions, at the micrometre scale (e.g. tilts of the crystalline planes in the vicinity of the junction edges), can be accurately characterized only using focused X-ray beams. These local defects are dependent on the junction shape and larger by one order of magnitude than the macroscopic curvature of the sample.

Mocuta, Cristian; Barbier, Antoine; Stanescu, Stefan; Matzen, Sylvia; Moussy, Jean-Baptiste; Ziegler, Eric

2013-01-01

253

Measurement of relative K X-ray intensity ratio following radioactive decay and photoionization  

NASA Astrophysics Data System (ADS)

The measurements of the K X-ray intensity ratio I(K ?2/K ?1), I(K ?1/K ?1) and I(K ?/K ?) for elements V, Mn, Zn, Tc, Ru, Cd, Xe, Ba, Cs, Hg and Rn were experimentally determined both by photon excitation, in which 59.5 keV ?-rays from a 241Am and 123.6 keV ?-rays from a 60Co were used, and following the radioactive decay of 51Cr, 55Fe, 67Ga, 99Tc, 111In, 131I, 133Ba, 133Xe, 137Cs, 201Tl and 226Ra. K X-rays emitted by samples were counted by a Si(Li) detector with resolution 160 eV at 5.9 keV. Obtained values were compared with the theoretical values. It was observed that present values agree with the previous theoretical and other experimental results.

Yalç?n, P.

2007-01-01

254

Analysis of a high intensity x-ray source using a specialized Doppler interferometer system  

NASA Astrophysics Data System (ADS)

The Saturn accelerator at Sandia National Laboratories is a high power, variable-spectrum, x-ray source capable of simulating radiation effects of nuclear countermeasures on electronic and material components of space systems. It can also function as a pulsed-power and radiation source, and as a diagnostic test bed for a variety of applications. Obtaining highly accurate measurements of the emission spectra is difficult because the high intensity x-rays and MegaAmpere levels of current inside the experiment chamber can damage or destroy electronic measurement devices. For these reasons, an optical based measurement system has been designed, developed and successfully tested in the Saturn accelerator. The system uses fiber optic coupled sensor(s) connected to a specialized Doppler interferometer system which analyzes the shock wave imparted into a target material. This paper describes the optical system, its related components, and material response data of polymethyl methacrylate.

Fleming, K. J.

255

Analysis of a high intensity x-ray source using a specialized doppler interferometer system  

NASA Astrophysics Data System (ADS)

The Saturn accelerator at Sandia National Laboratories is a high power, variable-spectrum, x-ray source capable of simulating radiation effects of nuclear countermeasures on electronic and material components of space systems. It can also function as a pulsed-power and radiation source, and as a diagnostic test bed for a variety of applications. Obtaining highly accurate measurements of the emission spectra is difficult because the high intensity x-rays and MegaAmpere levels of current inside the experiment chamber can damage or destroy electronic measurement devices. For these reasons, an optical based measurement system has been designed, developed and successfully tested in the Saturn accelerator. The system uses fiber optic coupled sensor(s) connected to a specialized Doppler interferometer system which analyzes the shock wave imparted into a target material. This paper describes the optical system, its related components, and material response data of polymethyl methacrylate.

Fleming, K. J.

1996-05-01

256

Synchrotron-based coherent scatter x-ray projection imaging using an array of monoenergetic pencil beams.  

PubMed

Traditional projection x-ray imaging utilizes only the information from the primary photons. Low-angle coherent scatter images can be acquired simultaneous to the primary images and provide additional information. In medical applications scatter imaging can improve x-ray contrast or reduce dose using information that is currently discarded in radiological images to augment the transmitted radiation information. Other applications include non-destructive testing and security. A system at the Canadian Light Source synchrotron was configured which utilizes multiple pencil beams (up to five) to create both primary and coherent scatter projection images, simultaneously. The sample was scanned through the beams using an automated step-and-shoot setup. Pixels were acquired in a hexagonal lattice to maximize packing efficiency. The typical pitch was between 1.0 and 1.6 mm. A Maximum Likelihood-Expectation Maximization-based iterative method was used to disentangle the overlapping information from the flat panel digital x-ray detector. The pixel value of the coherent scatter image was generated by integrating the radial profile (scatter intensity versus scattering angle) over an angular range. Different angular ranges maximize the contrast between different materials of interest. A five-beam primary and scatter image set (which had a pixel beam time of 990 ms and total scan time of 56 min) of a porcine phantom is included. For comparison a single-beam coherent scatter image of the same phantom is included. The muscle-fat contrast was 0.10 ± 0.01 and 1.16 ± 0.03 for the five-beam primary and scatter images, respectively. The air kerma was measured free in air using aluminum oxide optically stimulated luminescent dosimeters. The total area-averaged air kerma for the scan was measured to be 7.2 ± 0.4 cGy although due to difficulties in small-beam dosimetry this number could be inaccurate. PMID:23020426

Landheer, Karl; Johns, Paul C

2012-09-01

257

Ground-based x-ray calibration of the Astro-E2 x-ray telescope: II. With diverging beam at PANTER  

NASA Astrophysics Data System (ADS)

We report a ground-based X-ray calibration of the Astro-E2 X-ray telescope at the PANTER test facility. Astro-E2, to be launched in February 2005, has five X-Ray Telescopes (XRTs). Four of them focus on the X-Ray Imaging Spectrometers (XIS) while the other on the X-Ray Spectrometer (XRS). They are designed with a conical approximation of Wolter-I type optics, nested with thin foil mirrors to enhance their throughput. A calibration test of the first Astro-E2 flight XRT for XIS was carried out at the PANTER facility in August 2003. This facility has an 130 meter long diverging beam from X-ray generator to XRT. Owing to the small X-ray spot size of about 2 mm dia., we verified that the focal position of each quadrant unit converged within 10 arcsec. The energy band around Au-M edge structures was scanned with a graphite crystal. The edge energy (Au M5) is consistent with that listed in Henke et al. 1997. Owing to the large area coverage of the PSPC detector which is a spare of the ROSAT satellite, off-axis images including stray lights at large off-axis angle (up to 6 degree) were obtained with a large field of view. We also compared the results with those measured with the parallel pencil beam at ISAS which is in detail reported in our companion paper by Itoh A. et al..

Itoh, Kei; Kunieda, Hideyo; Maeda, Yoshitomo; Misaki, Kazutami; Serlemitsos, Peter J.; Shibata, Ryo; Budau, Bernd; Burkert, Wolfgang; Freyberg, Michael J.; Hartner, Gisela; Chan, Kai-Wing; Haba, Yoshito; Hayakawa, Akira; Iizuka, Ryo; Inoue, Chiaki; Inoue, Hirohiko; Ishida, Manabu; Itoh, Akiharu; Lehan, John P.; Mori, Hideyuki; Naitou, Masataka; Okada, Shunsaku; Okajima, Takashi; Shimizu, Tomoo; Soong, Yang; Yokoyama, Yushi

2004-10-01

258

Vagus nerve stimulator stability and interference on radiation oncology x-ray beams  

NASA Astrophysics Data System (ADS)

Five different models of Cyberonics, Inc. vagus nerve stimulation (VNS) therapy pulse generators were investigated for their stability under radiation and their ability to change the absorbed dose from incident radiation. X-ray beams of 6 MV and 18 MV were used to quantify these results up to clinical doses of 68-78 Gy delivered in a single fraction. In the first part, the effect on electronic stimulation signaling of each pulse generator was monitored during and immediately afterwards with computer interrogation. In the second part, the effects of having the pulse generators scatter or attenuate the x-ray beam was also characterized from dose calculations on a treatment planning system as well as from actual radiation measurements. Some device models were found to be susceptible to radiation interference when placed directly in the beam of high energy therapeutic x-ray radiation. While some models exhibited no effect at all, others showed an apparent loss of stimulation output immediately after radiation was experienced. Still, other models were observed to have a cumulative dose effect with a reduced output signal, followed by battery depletion above 49 Gy. Absorbed dose changes on computer underestimated attenuation by nearly half for both energies amongst all pulse generators, although the computer did depict the proper shape of the changed distribution of dose around the device. Measured attenuation ranged from 7.0% to 11.0% at 6 MV and 4.2% to 5.2% at 18 MV for x-rays. Processes of back-scatter and side-scatter were deemed negligible although recorded. Identical results from 6 MV and 18 MV x-ray beams conclude no neutron effect was induced for the 18 MV beam. As there were documented effects identified in this research regarding pulse generation, it emphasizes the importance of caution when considering radiation therapy on patients with implanted VNS devices with observed malfunctions consequential.

Gossman, Michael S.; Ketkar, Amruta; Liu, Arthur K.; Olin, Bryan

2012-10-01

259

Vagus nerve stimulator stability and interference on radiation oncology x-ray beams.  

PubMed

Five different models of Cyberonics, Inc. vagus nerve stimulation (VNS) therapy pulse generators were investigated for their stability under radiation and their ability to change the absorbed dose from incident radiation. X-ray beams of 6 MV and 18 MV were used to quantify these results up to clinical doses of 68-78 Gy delivered in a single fraction. In the first part, the effect on electronic stimulation signaling of each pulse generator was monitored during and immediately afterwards with computer interrogation. In the second part, the effects of having the pulse generators scatter or attenuate the x-ray beam was also characterized from dose calculations on a treatment planning system as well as from actual radiation measurements. Some device models were found to be susceptible to radiation interference when placed directly in the beam of high energy therapeutic x-ray radiation. While some models exhibited no effect at all, others showed an apparent loss of stimulation output immediately after radiation was experienced. Still, other models were observed to have a cumulative dose effect with a reduced output signal, followed by battery depletion above 49 Gy. Absorbed dose changes on computer underestimated attenuation by nearly half for both energies amongst all pulse generators, although the computer did depict the proper shape of the changed distribution of dose around the device. Measured attenuation ranged from 7.0% to 11.0% at 6 MV and 4.2% to 5.2% at 18 MV for x-rays. Processes of back-scatter and side-scatter were deemed negligible although recorded. Identical results from 6 MV and 18 MV x-ray beams conclude no neutron effect was induced for the 18 MV beam. As there were documented effects identified in this research regarding pulse generation, it emphasizes the importance of caution when considering radiation therapy on patients with implanted VNS devices with observed malfunctions consequential. PMID:23032351

Gossman, Michael S; Ketkar, Amruta; Liu, Arthur K; Olin, Bryan

2012-10-21

260

The effect of beam-driven return current instability on solar hard X-ray bursts  

NASA Astrophysics Data System (ADS)

The problem of electrostatic wave generation by a return current driven by a small area electron beam during solar hard X-ray bursts is discussed. The marginal stability method is used to solve numerically the electron and ion heating equations for a prescribed beam current evolution. When ion-acoustic waves are considered, the method appears satisfactory and, following an initial phase of Coulomb resistivity in which Te/T sub i rise, predicts a rapid heating of substantial plasma volumes by anomalous ohmic dissipation. This hot plasma emits so much thermal bremsstrahlung that, contrary to previous expectations, the unstable beam-plasma system actually emits more hard X-rays than does the beam in the purely collisional thick target regime relevant to larger injection areas. Inclusion of ion-cyclotron waves results in ion-acoustic wave onset at lower Te/T sub i and a marginal stability treatment yields unphysical results.

Cromwell, D.; McQuillan, P.; Brown, J. C.

261

The effect of beam-driven return current instability on solar hard X-ray bursts  

NASA Technical Reports Server (NTRS)

The problem of electrostatic wave generation by a return current driven by a small area electron beam during solar hard X-ray bursts is discussed. The marginal stability method is used to solve numerically the electron and ion heating equations for a prescribed beam current evolution. When ion-acoustic waves are considered, the method appears satisfactory and, following an initial phase of Coulomb resistivity in which T sub e/T sub i rise, predicts a rapid heating of substantial plasma volumes by anomalous ohmic dissipation. This hot plasma emits so much thermal bremsstrahlung that, contrary to previous expectations, the unstable beam-plasma system actually emits more hard X-rays than does the beam in the purely collisional thick target regime relevant to larger injection areas. Inclusion of ion-cyclotron waves results in ion-acoustic wave onset at lower T sub e/T sub i and a marginal stability treatment yields unphysical results.

Cromwell, D.; Mcquillan, P.; Brown, J. C.

1986-01-01

262

Inclination Effects and Beaming in Black Hole X-Ray Binaries  

NASA Astrophysics Data System (ADS)

We investigate the dependence of observational properties of black hole X-ray binaries on the inclination angle i of their orbits. We find the following: (1) Transient black hole binaries show no trend in their quiescent X-ray luminosities as a function of i, suggesting that the radiation is not significantly beamed. This is consistent with emission from an accretion disk. If the X-rays are from a jet, then the Lorentz factor ? of the jet is <1.24 at the 90% confidence level. (2) The X-ray binary 4U 1543-47 with i~21deg has a surprisingly strong fluorescent iron line in the high soft state. Quantifying an earlier argument by Park et al., we conclude that if the continuum X-ray emission in this source is from a jet, then ?<1.04. (3) None of the known binaries has cosi<0.25 or i>75deg. This fact, plus the lack of eclipses among the 20 black hole binaries in our sample, strongly suggests at the 99.5% confidence level that systems with large inclination angles are hidden from view. The obscuration could be the result of disk flaring, as suggested by Milgrom for neutron star X-ray binaries. (4) Transient black hole binaries with i~70deg-75deg have significantly more complex X-ray light curves than systems with i<~65deg. This may be the result of variable obscuration and/or variable height above the disk of the radiating gas.

Narayan, Ramesh; McClintock, Jeffrey E.

2005-04-01

263

Mapping the continuous reciprocal space intensity distribution of X-ray serial crystallography.  

PubMed

Serial crystallography using X-ray free-electron lasers enables the collection of tens of thousands of measurements from an equal number of individual crystals, each of which can be smaller than 1 µm in size. This manuscript describes an alternative way of handling diffraction data recorded by serial femtosecond crystallography, by mapping the diffracted intensities into three-dimensional reciprocal space rather than integrating each image in two dimensions as in the classical approach. We call this procedure 'three-dimensional merging'. This procedure retains information about asymmetry in Bragg peaks and diffracted intensities between Bragg spots. This intensity distribution can be used to extract reflection intensities for structure determination and opens up novel avenues for post-refinement, while observed intensity between Bragg peaks and peak asymmetry are of potential use in novel direct phasing strategies. PMID:24914160

Yefanov, Oleksandr; Gati, Cornelius; Bourenkov, Gleb; Kirian, Richard A; White, Thomas A; Spence, John C H; Chapman, Henry N; Barty, Anton

2014-07-17

264

Mapping the continuous reciprocal space intensity distribution of X-ray serial crystallography  

PubMed Central

Serial crystallography using X-ray free-electron lasers enables the collection of tens of thousands of measurements from an equal number of individual crystals, each of which can be smaller than 1 µm in size. This manuscript describes an alternative way of handling diffraction data recorded by serial femtosecond crystallography, by mapping the diffracted intensities into three-dimensional reciprocal space rather than integrating each image in two dimensions as in the classical approach. We call this procedure ‘three-dimensional merging’. This procedure retains information about asymmetry in Bragg peaks and diffracted intensities between Bragg spots. This intensity distribution can be used to extract reflection intensities for structure determination and opens up novel avenues for post-refinement, while observed intensity between Bragg peaks and peak asymmetry are of potential use in novel direct phasing strategies.

Yefanov, Oleksandr; Gati, Cornelius; Bourenkov, Gleb; Kirian, Richard A.; White, Thomas A.; Spence, John C. H.; Chapman, Henry N.; Barty, Anton

2014-01-01

265

Iterative X-ray Cone-Beam Tomography for Metal Artifact Reduction and Local Region Reconstruction  

Microsoft Academic Search

X-ray cone-beam reconstruction from incomplete projection data has important practical applica- tions, especially in microtomography. We developed expectation maximization (EM)-type and algebraic re- construction technique (ART)-type iterative cone-beam reconstruction algorithms for metal artifact reduction and local reconstruction from truncated data. These iterative algorithms are adapted from the emission computerized tomography (CT) EM formula and the ART. A key step in

Ge Wang; Michael W. Vannier; Ping-Chin Cheng

1999-01-01

266

X-ray spectra of Hercules X-1. 2: Intrinsic beam  

NASA Technical Reports Server (NTRS)

The X-ray spectrum of Hercules X-1 was observed in the energy range 2-24 keV with sufficient temporal resolution to allow detailed study of spectral correlations with the 1.24 sec pulse phase. A region of spectral hardening which extends over approximately the 1/10 pulse phase may be associated with the underlying beam. The pulse shape stability and its asymmetry relative to this intrinsic beam are discussed.

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

1977-01-01

267

Wide-angle monochromatic x-ray beam shutter: a design study  

Microsoft Academic Search

A novel design of a wide-angle monochromatic x-ray beam shutter is discussed. The shutter is designed as a compact unit capable of providing users with the means of shutting off the beam in secondary beamlines that are at an angle to the primary beamline and to each other. The single-unit design used the fact that all the secondary beamlines will

Bran Brajuskovic; Joseph Chang; Frank Carrera; Laurence Lourio; Jean-Francois Pelletier; Deming Shu

2002-01-01

268

Wide-angle monochromatic x-ray beam shutter: a design study  

Microsoft Academic Search

A novel design of a wide-angle monochromatic x-ray beam shutter is discussed. The shutter is designed as a compact unit capable of providing users with the means of shutting off the beam in secondary beamlines that are at an angle to the primary beamline and to each other. The single-unit design used the fact that all the secondary beamlines will

Bran Brajuskovic; Joseph Chang; Frank Carrera; Laurence Lurio; Jean-Francois Pelletier; Deming Shu

2003-01-01

269

Directionality effects in the transfer of X-rays from a magnetized atmosphere: Beam pulse shape  

NASA Technical Reports Server (NTRS)

A formalism is presented for radiation transfer in two normal polarization modes in finite and semiinfinite plane parallel uniform atmospheres with a magnetic field perpendicular to the surface and arbitrary propagation angles. This method is based on the coupled integral equations of transfer, including emission, absorption, and scattering. Calculations are performed for atmosphere parameters typical of X-ray pulsars. The directionality of the escaping radiation is investigated for several cases, varying the input distributions. Theoretical pencil beam profiles and X-ray pulse shapes are obtained assuming the radiation is emitted from the polar caps of spinning neutron stars. Implications for realistic models of accreting magnetized X-ray sources are briefly discussed.

Meszaros, P.; Bonazzola, S.

1981-01-01

270

Trident pair production in colliding bright x-ray laser beams  

NASA Astrophysics Data System (ADS)

The development of strong x-ray lasers motivates the advancement of pair production studies into regions of higher laser frequency. In this paper, a resonant electron-positron pair production process with the absorption of two x-ray photons is considered in the impact of an energetic electron at the overlap region of two colliding x-ray laser beams. The laser-dressed QED method is justified to tackle the complexity of the corresponding multiple Feynman diagrams calculation. The dependence of the production rate as well as the positron energy distribution on the relative angles among the directions of the two laser wave vectors and the incoming electron momentum is revealed. It is shown that the non-plane-wave laser field configuration arouses additional features in the pair production process compared to the plane-wave case.

Hu, Huayu; Huang, Jie

2014-03-01

271

Measurement of fast neutrons produced by high-energy X-ray beams of medical electron accelerators  

Microsoft Academic Search

The fast neutron contamination associated with the 25 MV X-ray beam of a clinical linear accelerator and with the 19 MV X-ray beam of a betatron has been measured at the patient treatment location, using both fission fragment track detectors and silicon diode dosemeters. Measurements are made of the neutron fluence and dose, both in and out of the primary

R. M. Wilenzick; P. R. Almond; G. D. Oliver; C. E. De Almeida

1973-01-01

272

Infrared/X-ray intensity variations and the color of Sgr A*  

NASA Astrophysics Data System (ADS)

We report the frst time-series measurements of Sgr A*-IR's broadband infrared color. Using the newly commissioned laser guide star adaptive optics (LGS AO) system on the Keck II telescope, we imaged Sgr A*-IR, in the broadband liters H (1.6 ?m), K' (2.1 ?m), and L' (3.8 ?m) every 3 minutes over the course of 120 minutes, during which time the Chandra X-ray Observatory was also monitoring the Galactic center. Complementary measurements of Sgr A*'s L'- and Ms (4.7 ?m)-band flux densities were obtained on a separate night with the natural guide star AO system. During our observations, Sgr A*-IR,'s flux density showed a wide range of values (2 to 12 mjy at 2.1 ?m), which are associated with at least 4 peaks in the infrared emission and are among its highest infrared flux density measurements. However, all our near-infrared color measurements are consistent with a constant spectral slope of ? = -0.9 ± 0.2 (F? propto ??), independent of intensity, wavelength, time, or outburst. Assuming that the infrared wavelengths probe synchrotron emission, we interpret the lack of variation in the infrared spectral index as an indication that the acceleration mechanism leaves the distribution of the bulk of the electrons responsible for the infrared emission unchanged. During our coordinated infrared observations, no elevated X-ray emission was detected. While the less frequent X-ray outbursts have shown correlated emission in previous studies, the lack of X-ray variation during the signifbant infrared variations reported here indicates that one may not be able to connect the infrared and X-ray emission to the same electrons. We suggest that while the acceleration mechanism leaves the bulk of the electron energy distribution unchanged, it generates a variable high-energy tail. It is this high-energy tail that gives rise to the less frequent X-ray outbursts.

Hornstein, S. D.; Matthews, K.; Ghez, A. M.; Lu, J. R.; Morris, M.; Becklin, E. E.; Baganoff, F. K.; Rafelski, M.

2006-12-01

273

Intense High-Contrast Femtosecond K-Shell X-Ray Source from Laser-Driven Ar Clusters  

SciTech Connect

Bright Ar quasimonochromatic K-shell x ray with very little background has been generated using an Ar clustering gas jet target irradiated with a 30 fs ultrahigh-contrast laser, with a measured flux of 2.2x10{sup 11} photons/J into 4{pi}. This intense x-ray source critically depends on the laser contrast and intensity. The optimization of source output with interaction length is addressed. Simulations point to a nonlinear resonant mechanism of electron heating during the early stage of laser interaction, resulting in enhanced x-ray emission. The x-ray pulse duration is expected to be only 10 fs, opening the possibility for single-shot ultrafast keV x-ray imaging applications.

Chen, L. M.; Liu, F.; Wang, W. M.; Mao, J. Y.; Zhang, L.; Ma, J. L.; Li, Y. T.; Wei, Z. Y. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Kando, M.; Bulanov, S. V.; Tajima, T.; Kato, Y. [Advanced Photon Research Center, Japan Atomic Energy Agency, 8-1 Umemidai Kizugawa, Kyoto 619-0215 (Japan); Sheng, Z. M.; Zhang, J. [Beijing National Laboratory of Condensed Matter Physics, Institute of Physics, CAS, Beijing 100080 (China); Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

2010-05-28

274

X-Ray Spectrum Model  

NSDL National Science Digital Library

TheX-Ray Spectrum Model shows the effect of varying the high voltage (kVp), added filtration and ripple in the high voltage supply to the X-ray tube. The physical mechanisms by which X-rays are produced are Bremsstrahlung (in which collisions of the cathode electrons convert some of their energy into X-ray photons) and characteristic X-rays (in which the cathode electrons kick an inner shell electron out of an atom, and an X-ray photon is release when one of the atom's outer shell electron transitions to the inner shell). Changing the accelerating voltage of the cathode electrons (i.e. changing kVp) affects both mechanisms of X-ray production. Adding filtration to the X-ray beam reduces its intensity, but does not reduce all energy X-rays equally. The X-Ray Spectrum Model was created by Michael Gallis using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. You can examine and modify this compiled EJS model if you run the model (double click on the model's jar file), right-click within a plot, and select "Open Ejs Model" from the pop-up menu. You must, of course, have EJS installed on your computer. 

Gallis, Michael R.

2014-04-16

275

An evaluation of ionization chambers for the relative dosimetry of kilovoltage x-ray beams  

SciTech Connect

In this work, the authors have evaluated ten different ionization chambers for the relative dosimetry of kilovoltage x-ray beams in the energy range of 50-280 kVp. Percentage depth doses in water and relative detector response (in Solid Water and in air) were measured for each of the x-ray beams studied using a number of chambers. Measured depth dose data were compared with Monte Carlo calculated depth doses using the EGSnrc Monte Carlo package and the BEAMnrc user code. The accuracy of the phase space files generated by BEAMnrc was verified by calculating the half-value layer and comparing with the measured half-value layer of each x-ray beam. The results indicate that the Advanced Markus, Markus, NACP, and Roos parallel plate ionization chambers were suitable for the measurement of depth dose data in this beam quality range with an uncertainty of less than 3%, including in the regions close to the water surface. While the relative detector response of the Farmer and scanning thimble chambers exhibited a better energy response, they were not suitable for depth dose measurements in the first 5 mm below the water surface with differences of up to 12% in the surface dose measurement for the 50 kVp x-ray beam. These differences were due to dose artifacts generated by the chamber size and the dose gradient. However, at depths greater than 5 mm, the Farmer and thimble scanning chambers gave uncertainties of less than 3% for the depth dose measurements for all beam energies. The PTW PinPoint 31006 chamber was found to give varying dose differences of up to 8% depending on the x-ray beam energy; this was attributed to the steel central electrode. The authors recommend that one of the parallel plate ionization chambers investigated be used to determine depth dose data for kilovoltage x-ray beams in the energy range studied and give correct dose information close to the surface and at depth in the water phantom.

Hill, Robin; Mo Zhao; Haque, Mamoon; Baldock, Clive [Institute of Medical Physics, School of Physics, University of Sydney, Sydney, 2006 (Australia) and Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, 2050 (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney, 2006 (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney, 2006 (Australia) and Department of Radiation Oncology, Royal Prince Alfred Hospital, Camperdown, 2050 (Australia); Institute of Medical Physics, School of Physics, University of Sydney, Sydney, 2006 (Australia)

2009-09-15

276

Recent progress on x-ray and pulsed particle beam sources at the Advanced Laser Light Source (ALLS) facility  

NASA Astrophysics Data System (ADS)

The 200TW laser system, (Ti:Sapphire CPA system) delivering 5J in 25fs pulse with a 10Hz repetition rate and a contrast ratio of 1:10^-11 at the fundamental 800nm frequency, is used at the Advanced Laser Light Source (ALLS) facility to develop new generation of x-ray and pulsed particle beam sources (electrons, protons, neutrons). Experimental results on the betatron emission and electron emission from high intensity (<10^19 W/cm2) interactions with gas jet targets (1cm long supersonic nozzle) and on proton generation during high intensity (10^20 W/cm2) laser interaction with thin foil (10nm) and thick (several µm) targets will be presented and discussed. With gas jet targets, very high-resolution single shot phase contrast imaging with 10-20 keV X-rays has been demonstrated, and electrons are currently generated in the GeV range. X-ray source characterization will be presented. With foil targets, the target expansion has been measured on both sides of the target as well as proton generation (15 MeV range) at these relativistic intensities with various diagnostics (folding wave interferometer, time of flight, Thomson parabola...) We will describe the progresses we are doing to move from the laboratory experiments system to the application levels with integrated systems and compact light sources, with a special emphasis on medical applications. We are exploring the use of these high power lasers as a basic tool to image in real time with X-rays (betatron emission) tumors during their irradiation by protons (accelerated by the same laser). + funded by NSERC, CIPI, CFI, FQRNT, MDEIE, INRS, CRC program.

Gnedyuk, S.; Fourmaux, S.; Payeur, S.; Lassonde, P.; MacLean, J. P.; Tchervenkov, C.; Glesser, M.; Marceau, V.; Piché, M.; Fuchs, J.; Krol, A.; Kieffer, J. C.

2012-10-01

277

The dosimetry of eye shields for kilovoltage X-ray beams.  

PubMed

The objective of this work was to evaluate the dosimetry of tungsten eye shields for use with kilovoltage X-ray beam treatments. The eye shields, originally designed for megavoltage electron beams, were made of 2 mm tungsten thickness and inside diameters of 11.6 and 15.0 mm with optional aluminium caps of 0.5 and 1 mm thickness. The relative dosimetry of the eye shields were examined by measurement of transmission doses with full scatter conditions, central axis depth doses and beam profiles underneath the eye shield. The X-ray beams used in this study ranged in energy from 50 to 280 kVp. Transmission measurements were performed using an Advanced Markus ionisation chamber located at the surface of an RMI457 Solid Water phantom with a 3 cm diameter applicator flush against the phantom surface. Depth doses and profiles measurements were performed in a PTW MP3 scanning water tank with a PTW diamond detector. Results for transmission doses for the medium size eye shield increased from 1 to 22 % for 50-280 kVp while for the smaller eye shield the percentage dose increased from 3.5 to 30 % for the same energy range. There were minimal differences between using the 0.5 and 1 mm aluminium caps. Central axis depth doses measured with and without the eye shields demonstrated the 125 and 180 kVp beams had higher peak doses behind the eye shields. These results show that these tungsten eye shields are suitable for use with kilovoltage X-ray beams. However, the clinical impact needs to be considered for the higher X-ray beam energies. PMID:23192598

Wang, D; Sobolewski, M; Hill, R

2012-12-01

278

MPD Intense Beam Pulser.  

National Technical Information Service (NTIS)

An MPD intense beam pulser for generating high voltage, intense charged particle beams utilizing an electromechanical energy source and inductive energy storage in combination with a plasma opening switch including a source of directed plasma flow, a diod...

P. J. Turchi I. M. Virkovitsky

1981-01-01

279

Conceptual Design of Dielectric Accelerating Structures for Intense Neutron and Monochromatic X-ray Sources  

NASA Astrophysics Data System (ADS)

Bright compact photon sources, which utilize electron beam interaction with periodic structures, may benefit a broad range of medical, industrial and scientific applications. A class of dielectric-loaded periodic structures for hard and soft X-ray production has been proposed that would provide a high accelerating gradient when excited by an external RF and/or primary electron beam. Target-distributed accelerators (TDA), in which an additional electric field compensates for lost beam energy in internal targets, have been shown to provide the necessary means to drive a high flux subcritical reactor (HFSR) for nuclear waste transmutation. The TDA may also be suitable for positron and nuclear isomer production, X-ray lithography and monochromatic computer tomography. One of the early assumptions of the theory of dielectric wake-field acceleration was that, in electrodynamics, the vector potential was proportional to the scalar potential. The analysis takes into consideration a wide range of TDA design aspects including the wave model of observed phenomena, a layered compound separated by a Van der Waals gap and a compact energy source based on fission electric cells (FEC) with a multistage collector. The FEC is a high-voltage power source that directly converts the kinetic energy of the fission fragments into electrical potential of about 2MV.

Blanovsky, Anatoly

2004-12-01

280

Conceptual Design of Dielectric Accelerating Structures for Intense Neutron and Monochromatic X-ray Sources  

SciTech Connect

Bright compact photon sources, which utilize electron beam interaction with periodic structures, may benefit a broad range of medical, industrial and scientific applications. A class of dielectric-loaded periodic structures for hard and soft X-ray production has been proposed that would provide a high accelerating gradient when excited by an external RF and/or primary electron beam. Target-distributed accelerators (TDA), in which an additional electric field compensates for lost beam energy in internal targets, have been shown to provide the necessary means to drive a high flux subcritical reactor (HFSR) for nuclear waste transmutation. The TDA may also be suitable for positron and nuclear isomer production, X-ray lithography and monochromatic computer tomography. One of the early assumptions of the theory of dielectric wake-field acceleration was that, in electrodynamics, the vector potential was proportional to the scalar potential. The analysis takes into consideration a wide range of TDA design aspects including the wave model of observed phenomena, a layered compound separated by a Van der Waals gap and a compact energy source based on fission electric cells (FEC) with a multistage collector. The FEC is a high-voltage power source that directly converts the kinetic energy of the fission fragments into electrical potential of about 2MV.

Blanovsky, Anatoly [Teacher Technology Center, 7850 Melrose Ave., Los Angeles, CA 90046 (United States)

2004-12-07

281

Considerations on Beam Quality Control in MIT X-Ray FEL  

SciTech Connect

The x-ray FEL at MIT is one example of a design for a new generation linac-based light source. Such a new machine requires very high quality electron beams. Besides the usual requirements on beam parameters such as emittance, energy spread, peak current, there are new challenges emerging in the design studies, e.g., the arrival timing of electron beam must reach precision below tens of femtoseconds level to ensure the laser seed overlaps the desired sections of electron bunch in the multiple-stage HGHG process. In this paper we report the progress on design optimization towards high quality and low sensitivity beams.

Wang, D.; Graves, W.; Wang, D.; Zwart, T.; /MIT, Bates Linear Accelerator; Emma, P.; Wu, J.; /SLAC; Huang, G.; /LBL, Berkeley

2006-03-15

282

Electron contamination of a high-energy X-ray beam.  

PubMed

The Lorentz force on an electron is utilised to separate out the electron component from the open beam of a Clinac-18, operating in the X-ray mode. The experimental arrangement is such that the mixed beam (comprising the primary photons, the scattered photons and the contamination electrons) enters an external magnetic field, which is perpendicular to the central axis of the beam. The electron contribution is analysed as a function of collimator setting, depth and distance. Based on the data, one is led to believe that the shift in dmax with field size is due to a relative enhancement in the soft X-ray component as the collimator jaws are opened. PMID:733897

Padikal, T N; Deye, J A

1978-11-01

283

High-Intensity X-Ray Holography: An Approach to High-Resolution Snapshot Imaging of Biological Specimens.  

National Technical Information Service (NTIS)

The crucial physical and technological issues pertaining to the holographic imaging of biological structures with a short-pulse, high-intensity, high-quantum-energy laser were examined. The limitations of x-ray optics are discussed. Alternative holographi...

J. C. Solem

1982-01-01

284

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

NASA Astrophysics Data System (ADS)

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.

Hruszkewycz, Stephan; Harder, Ross; Fuoss, Paul

2010-03-01

285

PBFA II lithium beam characterization from inner-shell x-ray images  

SciTech Connect

The Particle Beam Fusion Accelerator (PBFA II) is not driving targets with ICF-relevant lithium ion beams. During the most recent lithium beam target series, time-integrated x-ray pinhole cameras viewed the ion-induced inner-shell x-ray fluorescence from the central gold cone target and a titanium-coated strip. Ion beam profiles at a nominal 10 mm radius and fixed azimuthal direction were obtained from images of the Ti K{sub {alpha}}, fluorescence of a Ti-coated Al diagnostic wire. The gold cone gave us beam profiles at a nominal 3 mm radius and at all azimuthal angles from the Au L{sub {alpha}} fluorescence. From these profiles, we obtained the ion beam vertical focus position, full-width-at-half-maximum, and the degree of azimuthal uniformity for the lithium target shots. For these initial results, beam steering problems were evident. Azimuthal uniformity was measured from the ion beam footprint on the outer Au case (predominantly Au L{sub {alpha}}) of the hohlraum target and were found to be in the same range (up to 30%) as for previous proton beam target series. We then present plans for Li beam diagnostics for an upcoming target experimental series.

Moats, A.R.; Derzon, M.S.; Chandler, G.A.; Dukart, R.J.; Haill, T.A.

1994-05-01

286

Monte Carlo model of the scanning beam digital x-ray (SBDX) source.  

PubMed

The scanning-beam digital x-ray (SBDX) system has been developed for fluoroscopic imaging using an inverse x-ray imaging geometry. The SBDX system consists of a large-area x-ray source with a multihole collimator and a small detector. The goal of this study was to build a Monte Carlo (MC) model of the SBDX source as a useful tool for optimization of the SBDX imaging system in terms of its hardware components and imaging parameters. The MC model of the source was built in the EGSnrc/BEAMnrc code and validated using the DOSXYZnrc code and Gafchromic film measurements for 80, 100, and 120 kV x-ray source voltages. The MC simulated depth dose curves agreed with measurements to within 5%, and beam profiles at three selected depths generally agreed within 5%. Exposure rates and half-value layers for three voltages were also calculated from the MC simulations. Patient skin-dose per unit detector-dose was quantified as a function of patient size for all three x-ray source voltages. The skin-dose to detector-dose ratio ranged from 5-10 for a 20 cm thick patient to 1 × 10(3)-1 × 10(5) for a 50 cm patient for the 120 and 80 kV beams, respectively. Simulations of imaging dose for a prostate patient using common imaging parameters revealed that skin-dose per frame was as low as 0.2 mGy. PMID:23093305

Bazalova, M; Weil, M D; Wilfley, B; Graves, E E

2012-11-21

287

Ground-based x-ray calibration of the Astro-E2 x-ray telescope: I. With pencil beam  

NASA Astrophysics Data System (ADS)

We present X-ray characteristics of X-ray telescopes (XRTs) onboard the Astro-E2 satellite. It is scheduled to be launched in February 2005. We have been performed X-ray characterization measurements of XRTs at Institute of Space and Astronautical Science (ISAS) since January 2003. We adopted a raster scan method with a narrow X-ray pencil beam. Angular resolution of the Quadrants composed of the Astro-E2 XRT was evaluated to be 1$^{¥prime}$.6 -- 2$^{¥prime}$.2 (HPD; Half Power Diameter), irrespective of the X-ray energy, while those of the Astro-E XRT was 2$^{¥prime}$.0 -- 2$^{¥prime}$.2. The effective area of a telescope is approximately 450, 330, 250, and 170 [cm$^{2}$] at energies of 1.49, 4.51, 8.04, and 9.44 keV, respectively. The field of view (FOV) of the XRTs which is defined as Full Width Half Maximum (FWHM) of the vignetting function is $¥sim 18$ $^{¥prime}$ at 4.51 keV. We summarize these characters of the XRTs.

Itoh, Akiharu; Haba, Yoshito; Hayakawa, Akira; Iizuka, Ryo; Inoue, Chiaki; Inoue, Hirohiko; Ishida, Manabu; Itoh, Kei; Kunieda, Hideyo; Maeda, Yoshitomo; Misaki, Kazutami; Mori, Hideyuki; Naitou, Masataka; Okada, Shunsaku; Shibata, Ryo; Shimizu, Tomoo; Yokoyama, Yushi

2004-10-01

288

Intense Picosecond X-Ray Pulses from Laser Plasmas by Use of Nanostructured ``Velvet'' Targets  

NASA Astrophysics Data System (ADS)

We describe the optical, radiative, and laser-plasma physics of a new type of nanostructured surface especially promising as a very high absorption target for high-peak-power subpicosecond laser-matter interaction. This oriented-nanowire material, irradiated by 1 ps pulses at intensities up to 1017 W cm-2, produces picosecond soft x-ray pulses 50× more efficiently than do solid targets. We compare this to ``smoke'' or metallic clusters, and solid nanogroove-grating surfaces; the ``metal-velvet'' targets combine the high yield of smoke targets with the brief emission of grating surfaces.

Kulcsár, G.; Almawlawi, D.; Budnik, F. W.; Herman, P. R.; Moskovits, M.; Zhao, L.; Marjoribanks, R. S.

2000-05-01

289

Development of time resolved x-ray spectroscopy in high intensity laser-plasma interactions  

NASA Astrophysics Data System (ADS)

This article discusses the design of a novel time resolved von Hamos Bragg spectrometer to provide spectra in the region around the titanium K-? and He-? lines. The instrument consists of a highly oriented pyrolitic graphite mosaic crystal coupled to a picosecond x-ray streak camera. Measurements of the time dependent behavior from Ti foils illuminated with intense laser pulses can be used to improve the understanding of recombination dynamics, electron transport, and phase transitions in strongly coupled dense plasma. This is important for the modeling of the compression phase in inertial confinement fusion research and the study of astrophysical environments.

Notley, M. M.; Weber, R. L.; Fell, B.; Jeffries, J.; Freeman, R. R.; MacKinnon, A. J.; Dickson, R.; Hey, D.; Khattak, F.; Saiz, E. Garcia; Gregori, G.

2006-10-01

290

Electron beam stability and beam peak to peak motion data for NSLS X-Ray storage ring  

SciTech Connect

In the past two years, a significant reduction in electron beam motion has been achieved at the NSLS X-Ray storage ring. The implementation of global analog orbit feedbacks, based on a harmonics correction scheme, has reduced the beam motion globally. Implementation of six local analog feedback systems has reduced the beam motion even further at the corresponding beam line straight sections. This paper presents beam motion measurements, showing the improvement due to the feedback systems. Beam motion is measured using a spectrum analyzer and data is presented at various frequencies, where peaks were observed. Finally, some of the beam motion sources are discussed.

Singh, O.

1993-07-01

291

Resonant photo-pumping x-ray-laser scheme using intense characteristic x rays for water-window radiation generation  

SciTech Connect

A line pair for a resonant photo-pumping x-ray-laser scheme is proposed in which the wavelength matching between the aluminum K{alpha}{sub 2} line ({lambda}= 0.833 95 nm) and the 2p{sup 6}-(2p{sub 1/2},4d{sub 3/2}){sub 1} transition of the neonlike zinc ions ({lambda}= 0.834 00 nm) is used. The population kinetics code of the neonlike zinc ions in plasma under irradiation of the aluminum K{alpha} line shows that substantial amplification gain can be generated in the transition of (2p{sub 1/2},3p{sub 1/2}){sub 0}-(2p{sub 1/2},4d{sub 3/2}){sub 1} at a wavelength of 3.5 nm. We also investigate the experimental arrangement of this scheme, which implies that this scheme is feasible with the present ultra-short-pulse-laser technology.

Kawachi, Tetsuya [Quantum Beam Science Directorate, Japan Atomic Energy Agency (JAEA) 8-1-7, Umemidai, Kizugawa, Kyoto 619-0215 (Japan); Kato, Yoshiaki [Graduate School for the Creation of New Photonics Industries 1955-1, Kurematsu, Hamamatsu, Shizuoka 431-1202 (Japan)

2011-12-15

292

Chemical effects on the K?/K? X-ray intensity ratios of Mn, Ni and Cu complexes  

NASA Astrophysics Data System (ADS)

Chemical effects on the K?/K? X-ray intensity ratios for some Mn, Ni, and Cu complexes of a new schiff-base with salen N2H2 type were investigated. The samples were excited by 59.543 keV ?-rays from a 241Am annular radioactive source. K X-rays emitted by samples were counted by a Si(Li) detector with resolution 157 eV at 5.9 keV. We observed the chemical effect on the K?/K? X-ray intensity ratios for Mn, Ni and Cu complexes. The experimental results showed that the K?/K? X-ray intensity ratios for compounds with complexes are generally larger than those with salt form. The experimental values have been compared with the other experimental and the theoretically calculated values of pure elements. The results are in very good agreement with the others.

Çevik, U.; De?irmencio?lu, I.; Ertu?ral, B.; Apayd?n, G.; Balta?, H.

2005-10-01

293

Synchrotron-based coherent scatter x-ray projection imaging using an array of monoenergetic pencil beams  

NASA Astrophysics Data System (ADS)

Traditional projection x-ray imaging utilizes only the information from the primary photons. Low-angle coherent scatter images can be acquired simultaneous to the primary images and provide additional information. A system at the Canadian Light Source synchrotron was configured which utilizes multiple 33.17 keV pencil beams (up to five) to create both primary and coherent scatter projection images, simultaneously. The sample was scanned through the beams using an automated step-and-shoot setup. Pixels were acquired in a hexagonal lattice to maximize packing efficiency. The typical pitch was between 1.0 and 1.6 mm. An MLEM-based iterative method was used to disentangle the overlapping information from the flat panel digital x-ray detector. The pixel value of the coherent scatter image was generated by integrating the radial profile (scatter intensity versus scattering angle) over an angular range. Different angular ranges maximize the contrast between different materials. For a five-beam porcine phantom image the muscle-fat contrast was 0.10 +/- 0.01 and 1.16 +/- 0.03 for the primary and scatter images, respectively. The air kerma was measured using Al2O3:C optically stimulated luminescent dosimeters. The total area-averaged air kerma for the scan was measured to be (7.2 +/- 0.4) cGy although, due to difficulties in small-beam dosimetry, this number could be inaccurate.

Landheer, Karl

294

Ion beam lithography for Fresnel zone plates in X-ray microscopy  

NASA Astrophysics Data System (ADS)

Fresnel Zone Plates (FZP) are to date very successful focusing optics for X-rays. Established methods of fabrication are rather complex and based on electron beam lithography (EBL). Here, we show that ion beam lithography (IBL) may advantageously simplify their preparation. A FZP operable from the extreme UV to the limit of the hard X-ray was prepared and tested from 450 eV to 1500 eV. The trapezoidal profile of the FZP favorably activates its 2nd order focus. The FZP with an outermost zone width of 100 nm allows the visualization of features down to 61, 31 and 21 nm in the 1st, 2nd and 3rd order focus respectively. Measured efficiencies in the 1st and 2nd order of diffraction reach the theoretical predictions.

Keskinbora, Kahraman; Grévent, Corinne; Bechtel, Michael; Weigand, Markus; Goering, Eberhard; Nadzeyka, Achim; Peto, Lloyd; Rehbein, Stefan; Schneider, Gerd; Follath, Rolf; Vila-Comamala, Joan; Yan, Hanfei; Schütz, Gisela

2013-05-01

295

Hard x-ray phase imaging using simple propagation of a coherent synchrotron radiation beam  

NASA Astrophysics Data System (ADS)

Particularly high coherence of the x-ray beam is associated, on the ID19 beamline at ESRF, with the small angular size of the source as seen from a point of the sample (0.1-1 µrad). This feature makes the imaging of phase objects extremely simple, by using a `propagation' technique. The physical principle involved is Fresnel diffraction. Phase imaging is being simultaneously developed as a technique and used as a tool to investigate light natural or artificial materials introducing phase variations across the transmitted x-ray beam. They include polymers, wood, crystals, alloys, composites or ceramics, exhibiting inclusions, holes, cracks, ... . `Tomographic' three-dimensional reconstruction can be performed with a filtered back-projection algorithm either on the images processed as in attenuation tomography, or on the phase maps retrieved from the images with a reconstruction procedure similar to that used for electron microscopy. The combination of diffraction (`topography') and Fresnel (`phase') imaging leads to new results.

Cloetens, Peter; Ludwig, Wolfgang; Baruchel, José; Guigay, Jean-Pierre; Pernot-Rejmánková, Petra; Salomé-Pateyron, Murielle; Schlenker, Michel; Buffière, Jean-Yves; Maire, Eric; Peix, Gilles

1999-05-01

296

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

SciTech Connect

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

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

1987-08-01

297

Wavefield characterization of nearly diffraction-limited focused hard x-ray beam with size less than 10 nm  

SciTech Connect

In situ wavefront compensation is a promising method to realize a focus size of only a few nanometers for x-ray beams. However, precise compensation requires evaluation of the wavefront with an accuracy much shorter than the wavelength. Here, we characterized a one-dimensionally focused beam with a width of 7 nm at 20 keV using a multilayer mirror. We demonstrate that the wavefront can be determined precisely from multiple intensity profiles measured around the beamwaist. We compare the phase profiles recovered from intensity profiles measured under the same mirror condition but with three different aperture sizes and find that the accuracy of phase retrieval is as small as {lambda}/12.

Kimura, Takashi; Mimura, Hidekazu; Handa, Soichiro; Yokoyama, Hikaru; Imai, Shota; Matsuyama, Satoshi; Sano, Yasuhisa [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Yumoto, Hirokatsu; Yabashi, Makina [SPring-8/Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Tamasaku, Kenji; Komura, Yoshiki [SPring-8/RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Nishino, Yoshinori [Research Institute for Electric Science, Hokkaido University, Kita 21 Nishi 10, Kita-ku, Sapporo 001-0021 (Japan); Ishikawa, Tetsuya [SPring-8/Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); SPring-8/RIKEN, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan); Yamauchi, Kazuto [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2010-12-15

298

Incident photon energy and Z dependence of L X-ray relative intensities  

SciTech Connect

The intensity ratios, I{sub Lk}/I{sub L{alpha}1} (k = l, {eta}, {alpha}{sub 2}, {beta}{sub 1}, {beta}{sub 2,15}, {beta}{sub 3}, {beta}{sub 4}, {beta}{sub 5,7}, {beta}{sub 6}, {beta}{sub 9,10}, {gamma}{sub 1,5}, {gamma}{sub 6,8}, {gamma}{sub 2,3}, {gamma}{sub 4}), have been evaluated for elements with atomic number 36 {<=} Z {<=} 92 at incident photon energies ranging E{sub L1} < E{sub inc} {<=} 200 keV using currently considered to be more reliable theoretical data sets of different physical parameters, namely, L{sub i} (i = 1-3) subshell photoionization cross sections based on the relativistic Hartree-Fock-Slater model, the X-ray emission rates based on the Dirac-Fock model, and the fluorescence and Coster-Kronig yields based on the Dirac-Hartree-Slater model. At incident photon energies above the K-shell ionization threshold, the contribution to the production of different L X-ray lines due to the additional L{sub i} (i = 1-3) subshell vacancies created following decay of the primary K-shell vacancies have also been included in the present calculations. The important features pertaining to dependence of the tabulated intensity ratios on the incident photon energy and atomic number have been discussed.

Kumar, Anil; Chauhan, Yogeshwar [University College of Engineering, Punjabi University, Patiala 147002 (India); Puri, Sanjiv, E-mail: sanjivpurichd@yahoo.co [University College of Engineering, Punjabi University, Patiala 147002 (India)

2010-11-15

299

Wide-band, high-resolution soft x-ray spectrometer for the Electron Beam Ion Trap  

SciTech Connect

We have constructed two wide-band, high-resolution vacuum flat crystal spectrometers and implemented them on the Electron Beam Ion Trap located at the Lawrence Livermore National Laboratory. Working in unison, these spectrometers can measure an x-ray bandwidth {le}9 {Angstrom} in the soft x-ray region below 21 {Angstrom}. In order to achieve this large bandwidth each spectrometer houses either two 125 mm {times} 13 mm {times} 2 mm RAP (rubidium acid phthalate, 2d=26.121 {Angstrom}), two 114 mm {times} 13 mm {times} 2 mm TlAP (thallium acid phthalate, 2d=25.75 {Angstrom}) crystals, or some combination thereof, for dispersion and two position sensitive proportional counters for detection of x rays. The spectrometers are used to measure wavelengths and relative intensities of the L-shell line emission from FethinspXVII{endash}XXIV for comparison with spectra obtained from astrophysical and laboratory plasmas. The wide wavelength coverage attainable by these spectrometers makes it possible to measure all the L-shell emission from a given iron ion species simultaneously. {copyright} {ital 1999 American Institute of Physics.}

Brown, G.V.; Beiersdorfer, P.; Widmann, K. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

1999-01-01

300

Flash X-Ray (FXR) Accelerator Optimization - Beam-induced Voltage Simulation and TDR Measurements  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) is evaluating design alternatives to improve the voltage regulation in our Flash X-Ray (FXR) accelerator cell and pulse-power system. The goal is to create a more mono-energetic electron beam that will create an x-ray source with a smaller spot-size. Studying the interaction of the beam and accelerator cell will generate improved designs for high-current accelerators at Livermore and elsewhere. When an electron beam crosses the energized gap of an accelerator cell, the electron energy is increased. However, the beam with the associated electromagnetic wave also looses a small amount of energy because of the increased impedance seen across the gap. The phenomenon is sometimes called beam loading. It can also be described as a beam-induced voltage at the gap which is time varying. This creates beam energy variations that we need to understand and control. A high-fidelity computer simulation of the beam and cell interaction has been completed to quantify the time varying induced voltage at the gap. The cell and pulse-power system was characterized using a Time-domain Reflectometry (TDR) measurement technique with a coaxial air-line to drive the cell gap. The beam-induced cell voltage is computed by convoluting the cell impedance with measured beam current. The voltage was checked against other measurements to validate the accuracy. The simulation results predicted that there are significant beam-induced gap voltage variations. Beam-induced voltages from different current profiles and cell impedances were simulated and compared. This allows us to predict the effect on voltage regulation for different design alternatives before making hardware changes and high-voltage testing. The beam-induced voltages are incorporated into a larger accelerator system-model to quantify their effect on total beam energy variations.

Ong, M M; Vogtlin, G E

2004-04-07

301

High gain, Fast Scan, Broad Spectrum Parallel Beam Wavelength Dispersive X-ray Spectrometer for SEM  

SciTech Connect

During contract # DE-FG02-ER83545, Parallax Research, Inc. developed a High gain, Fast Scan Broad Spectrum Parallel beam Wavelength Dispersive X-ray Spectrometer for use on Scanning Electron Microscopes (SEM). This new spectrometer allows very fast high resolution elemental analysis of samples in an electron microscope. By comparison to previous WDS spectrometers, it can change from one energy position to another very quickly and has an extended range compared to some similar products.

OHara, David

2009-05-08

302

Characterization of a new large area HPGe X-ray detector for low beam current application  

Microsoft Academic Search

In the new sub-micron beamline at the Lund Nuclear Microprobe facility a special large area HPGe X-ray detector has been installed. It consists of eight 100-mm2-size detector elements arranged in an annular formation around the beam entrance hole. Different parameters like FWHM, FWTM, peak-to-background ratio and peak-to-valley ratio for each individual detector element as well as their sum spectra have

Asad Shariff; Per Kristiansson; Vaida Auzelyte; Mikael Elfman; Klas G. Malmqvist; Christer Nilsson; Jan Pallon; Marie Wegdén

2004-01-01

303

Beam Dynamics Study of X-Band Linac Driven X-Ray FELS  

Microsoft Academic Search

Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the

Yipeng

2011-01-01

304

Hard x-ray or gamma ray laser by a dense electron beam  

SciTech Connect

A dense electron beam propagating through a laser undulator can radiate a coherent x-ray or gamma ray. This lasing scheme is studied with the Landau damping theory. The analysis suggests that, with currently available physical parameters, coherent gamma rays of up to 50 keV can be generated. The electron quantum diffraction suppresses the free electron laser action, which limits the maximum radiation.

Son, S. [18 Caleb Lane, Princeton, New Jersey 08540 (United States); Joon Moon, Sung [8 Benjamin Rush Ln., Princeton, New Jersey 08540 (United States)

2012-06-15

305

Monte Carlo Simulation of the Conversion X-Rays from the Electron Beam of PFMA-3  

SciTech Connect

PFMA-3, a dense Plasma Focus device, is being optimized as an X-ray generator. X-rays are obtained from the conversion of the electron beam emitted in the backward direction and driven to impinge on a 50 {mu}m brass foil. Monte Carlo simulations of the X-ray emission have been conducted with MCNPX. The electron spectrum had been determined experimentally and is used in the present work as input to the simulations. Dose to the brass foil has been determined both from simulations and from measurements with a thermographic camera, and the two results are found in excellent agreement, thus validating further the electron spectrum assumed as well as the simulation set-up. X-ray emission has been predicted both from bremsstrahlung and from characteristic lines. The spectrum has been found to be comprised of two components of which the one at higher energy, 30 divide 70 keV, is most useful for IORT applications. The results are necessary to estimate penetration in and dose to Standard Human Tissue.

Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

2011-12-13

306

A Positional X-ray Instrumentation Test Stand For Beam-Line Experiments  

NASA Astrophysics Data System (ADS)

A multi-axis, motion controlled test stand has been built in the PSU 47 m X-ray beam-line for the purpose of testing X-ray instrumentation and mirrors using parallel rays. The test stand is capable of translation along two axes and rotation about two axes with motorized fine position control. The translation stages have a range of motion of 200 mm with a movement accuracy of ± 2.5 microns. Rotation is accomplished with a two-axis gimbal which can rotate 360° about one axis and 240° about another; movement with ± 35 arcsecond accuracy are achieved in both axes. The position and status are monitored using a LabView program. An XCalibr source with multiple target materials is used as an X-ray source and can produce multiple lines between 0.8 and 8 keV. Some sample spectra are shown from a Si-PIN diode detector. This system is well suited for testing X-ray mirror segments which are currently being developed.

Nikoleyczik, Jonathan; Prieskorn, Z.; Burrows, D. N.; Falcone, A.

2014-01-01

307

Design and characterization of electron beam focusing for X-ray generation in novel medical imaging architecturea)  

NASA Astrophysics Data System (ADS)

A novel electron beam focusing scheme for medical X-ray sources is described in this paper. Most vacuum based medical X-ray sources today employ a tungsten filament operated in temperature limited regime, with electrostatic focusing tabs for limited range beam optics. This paper presents the electron beam optics designed for the first distributed X-ray source in the world for Computed Tomography (CT) applications. This distributed source includes 32 electron beamlets in a common vacuum chamber, with 32 circular dispenser cathodes operated in space charge limited regime, where the initial circular beam is transformed into an elliptical beam before being collected at the anode. The electron beam optics designed and validated here are at the heart of the first Inverse Geometry CT system, with potential benefits in terms of improved image quality and dramatic X-ray dose reduction for the patient.

Bogdan Neculaes, V.; Zou, Yun; Zavodszky, Peter; Inzinna, Louis; Zhang, Xi; Conway, Kenneth; Caiafa, Antonio; Frutschy, Kristopher; Waters, William; De Man, Bruno

2014-05-01

308

Beryllium window and acoustic delay line design for x-ray lithography beam lines at the University of Wisconsin Center for X-ray Lithography  

SciTech Connect

X-ray lithography systems require sample chambers that can perform exposures in helium gas at atmospheric pressure. The interface between the experimental chamber and the beamline is critical for x-ray lithography and the storage ring. It must allow a high x-ray flux throughput while providing a vacuum barrier so that helium gas does not leak into the beam line and the storage ring. The beam line must also be designed to have protection in the case that a window does fail in order to minimize adverse effects to the ring and other systems. The details of the design for the vacuum system used on beam lines for the Center for X-ray Lithography at the University of Wisconsin Synchrotron Radiation Center 1-GeV electron storage ring are reported. Curved beryllium windows with a 1{times}5-cm{sup 2} aperture and 13 {mu}m thick that have a leak rate less than 10{sup {minus}10} Torr l/s have been successfully used at the experimental chamber beam-line interface. This thin flat beryllium foil is mounted in a curved housing with a wire seal to minimize helium leakage. The window assembly is designed and has been tested to withstand substantial overpressure before failure. If the beryllium window does fail, the beamline has an acoustic delay line that is designed to delay the incoming shock wave of helium gas so that a fast valve at the end of the beam line will close and minimize leakage of helium into the storage ring. The acoustic delay line is designed with baffles to slow the shock front and a secondary thin window to protect against molecular diffusion into the storage ring. The acoustic delay line has been tested to determine the effect of baffle design on delay of the shock wave. A theoretical model that provides a good description of the acoustic delay has also been developed.

Brodsky, E.L. (Center for X-ray Lithography, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589 (United States)); Hamilton, W. (Nuclear Engineering and Engineering Physics, University of Wisconsin, 153 Engineering Research Building, Madison, Wisconsin 53705 (United States)); Wells, G.; Cerrina, F. (Center for X-ray Lithography, University of Wisconsin, 3731 Schneider Drive, Stoughton, Wisconsin 53589 (United States)); Corradini, M. (Nuclear Engineering and Engineering Physics, University of Wisconsin, 153 Engineering Research Building, Madison, Wisconsin 53705 (United States))

1992-01-01

309

Revolution in x-ray optics.  

PubMed

In the past half decade or so there has been a technological revolution in our ability to generate, control, manipulate, focus, and detect x rays. The emergence of x-ray lasers and synchrotron insertion devices has increased the brightness of laboratory x-ray sources 8 to 12 orders of magnitude over what was available in the late 1960s. In addition, the past few years have been witness to significant advances in the development of normal incidence x-ray mirrors and beam splitters, diffraction limited x-ray lenses, x-ray microscopy, x-ray holography, x-ray waveguides, and CCD x-ray detector arrays. Utilizing these new capabilities, workers in the field are taking the first steps toward the development of sophisticated soft x-ray optical systems, including soft x-ray interferometers, high-intensity x-ray lasers, and projection optics for x-ray lithography. Details of these developments are discussed, as is the question, Why is this happening now? PMID:21307418

Ceglio, N M

1989-01-01

310

X-ray intensity fluctuation spectroscopy studies of ordering kinetics in a Cu-Pd alloy  

SciTech Connect

X-ray intensity fluctuation spectroscopy has been used to examine the coarsening kinetics in the classic long-period superlattice Cu-Pd alloy. The evolution of the speckle intensity was examined near the centers of both a superlattice peak (associated with local L1{sub 2} order) and a satellite peak (associated with one-dimensional antiphase correlations). The decay of the two-time correlation function C(t{sub 1},t{sub 2},q) was independent of the direction examined and was similar for the superlattice and satellite peaks. In agreement with published Langevin theory and simulations, the decay time {tau} of the two-time correlation function increases linearly with average time t{sub m}=(t{sub 1}+t{sub 2})/2. It is relatively independent of the wave vector near the peak centers. However, {tau} increases much more slowly with increasing t{sub m} than is expected.

Ludwig, K.; Livet, F.; Bley, F.; Simon, J.-P.; Caudron, R.; Le Bolloc'h, D.; Moussaid, A. [LTPCM-ENSEEG-INPG, UMR-CNRS No. 5614, Boite Postale 75-38402 Saint Martin d'Heres Cedex (France); ONERA-LEM, Boite Postale 72-29 Avenue de la Division Leclerc, 92322 Chatillon Cedex (France); Laboratoire Leon Brillouin (CEA-CNRS), CEA Saclay, 91191 Gif-sur-Yvette (France); Laboratoire de Physique des Solides, UMR CNRS 8502, bat. 510, universite Paris Sud, 91405 Orsay (France); ESRF, Boite Postale 220-38043, Grenoble (France)

2005-10-01

311

X-ray intensity fluctuation spectroscopy studies of ordering kinetics in a Cu-Pd alloy  

NASA Astrophysics Data System (ADS)

X-ray intensity fluctuation spectroscopy has been used to examine the coarsening kinetics in the classic long-period superlattice Cu-Pd alloy. The evolution of the speckle intensity was examined near the centers of both a superlattice peak (associated with local L12 order) and a satellite peak (associated with one-dimensional antiphase correlations). The decay of the two-time correlation function C(t1,t2,q) was independent of the direction examined and was similar for the superlattice and satellite peaks. In agreement with published Langevin theory and simulations, the decay time ? of the two-time correlation function increases linearly with average time tm=(t1+t2)/2 . It is relatively independent of the wave vector near the peak centers. However, ? increases much more slowly with increasing tm than is expected.

Ludwig, K.; Livet, F.; Bley, F.; Simon, J.-P.; Caudron, R.; Le Bolloc'H, D.; Moussaid, A.

2005-10-01

312

Intensity distribution of the x ray source for the AXAF VETA-I mirror test  

NASA Technical Reports Server (NTRS)

The X-ray generator for the AXAF VETA-I mirror test is an electron impact X-ray source with various anode materials. The source sizes of different anodes and their intensity distributions were measured with a pinhole camera before the VETA-I test. The pinhole camera consists of a 30 micrometers diameter pinhole for imaging the source and a Microchannel Plate Imaging Detector with 25 micrometers FWHM spatial resolution for detecting and recording the image. The camera has a magnification factor of 8.79, which enables measuring the detailed spatial structure of the source. The spot size, the intensity distribution, and the flux level of each source were measured with different operating parameters. During the VETA-I test, microscope pictures were taken for each used anode immediately after it was brought out of the source chamber. The source sizes and the intensity distribution structures are clearly shown in the pictures. They are compared and agree with the results from the pinhole camera measurements. This paper presents the results of the above measurements. The results show that under operating conditions characteristic of the VETA-I test, all the source sizes have a FWHM of less than 0.45 mm. For a source of this size at 528 meters away, the angular size to VETA is less than 0.17 arcsec which is small compared to the on ground VETA angular resolution (0.5 arcsec, required and 0.22 arcsec, measured). Even so, the results show the intensity distributions of the sources have complicated structures. These results were crucial for the VETA data analysis and for obtaining the on ground and predicted in orbit VETA Point Response Function.

Zhao, Ping; Kellogg, Edwin M.; Schwartz, Daniel A.; Shao, Yibo; Fulton, M. Ann

1992-01-01

313

Interaction of relativistic electrons with ultrashort laser pulses: Generation of femtosecond x-rays and microprobing of electron beams  

SciTech Connect

The interaction of relativistic electrons with terawatt femtosecond laser pulses is reviewed with emphasis on how the scattering process can be used as a source of ultrashort X-ray pulses and as a time-resolved diagnostic for measuring transverse and longitudinal phase space distributions of an electron beam with microns spatial and subpicosecond temporal resolution. Recent experimental results are presented in which 90{degree} Thomson scattering was utilized to generate 300 fs duration pulses of X-rays with peak energy of 30 keV. It is shown that, through analysis of the scattered X-ray beam properties, transverse and longitudinal distributions of the electron beam can be obtained.

Leemans, W.P.; Schoenlein, R.W.; Volfbeyn, P. [Lawrence Berkeley National Lab., CA (United States)] [and others] [Lawrence Berkeley National Lab., CA (United States); and others

1997-11-01

314

EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications  

SciTech Connect

The electron beam emitted from the back of Plasma Focus devices is being studied as a radiation source for intraoperative radiation therapy applications. A Plasma Focus device is being developed to this aim, to be utilized as an x-ray source. The electron beam is driven to impinge on 50 {mu}m brass foil, where conversion x-rays are generated. Measurements with gafchromic film are performed to analyse the attenuation of the x-rays beam and to predict the dose given to the culture cell in radiobiological experiments to follow.

Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory - DIENCA, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory - DIENCA, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, Ferrara University, via Saragat 1, I-44122 Ferrara (Italy); Mariotti, F. [ENEA, IRP-DOS, via dei Colli 16, I-40136 Bologna (Italy)

2012-09-01

315

EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications  

NASA Astrophysics Data System (ADS)

The electron beam emitted from the back of Plasma Focus devices is being studied as a radiation source for intraoperative radiation therapy applications. A Plasma Focus device is being developed to this aim, to be utilized as an x-ray source. The electron beam is driven to impinge on 50 ?m brass foil, where conversion x-rays are generated. Measurements with gafchromic film are performed to analyse the attenuation of the x-rays beam and to predict the dose given to the culture cell in radiobiological experiments to follow.

Ceccolini, E.; Rocchi, F.; Mostacci, D.; Sumini, M.; Tartari, A.; Mariotti, F.

2012-09-01

316

Ray-tracing simulations of spherical Johann diffraction spectrometer for in-beam X-ray experiments  

NASA Astrophysics Data System (ADS)

The results of the Monte-Carlo ray-tracing simulations for a Johann-type Bragg spectrometer with spherically curved-crystal designed to detect the X-rays from a fast-moving source are reported. These calculations were performed to optimize the X-ray spectrometer to be used at the gas-target installed at ion storage ring for high-resolution X-ray experiments. In particular, the two-dimensional distributions of detected photons were studied using the Monte-Carlo method both for the stationary and moving X-ray sources, taking into account a detailed description of X-ray source and X-ray diffraction on the crystal as well as a role of the Doppler effect for in-beam experiments. The origin of the asymmetry of observed X-ray profiles was discussed in detail and the procedure to derive a precise (sub-eV) X-ray transition energy for such asymmetric profiles was proposed. The results are important for the investigations of 1s2pP23?1s2sS13 intrashell transition in excited He-like uranium ions in in-beam X-ray experiments.

Jagodzi?ski, P.; Pajek, M.; Bana?, D.; Beyer, H. F.; Trassinelli, M.; Sto¨hlker, Th.

2014-07-01

317

CALIBRATION OF X-RAY IMAGING DEVICES FOR ACCURATE INTENSITY MEASUREMENT  

Microsoft Academic Search

National Security Technologies (NSTec) has developed calibration procedures for X-ray imaging systems. The X-ray sources that are used for calibration are both diode type and diode\\/fluorescer combinations. Calibrating the X-ray detectors is key to accurate calibration of the X-ray sources. Both energy dispersive detectors and photodiodes measuring total flux were used. We have developed calibration techniques for the detectors using

M J Haugh; M R Charest; P W Ross; J J Lee; M B Schneider; N E Palmer; A T Teruya

2012-01-01

318

A study of diagnostic x-ray lines in heliumlike neon using an electron beam ion trap  

SciTech Connect

Heliumlike ions play an extremely important role in X-ray astrophysics because of their emissivity and because the relative intensities of their emission lines can be used to infer physical characteristics of X-ray emitting plasmas, including temperature, electron density, and ionization balance. In order to properly apply these diagnostics, accurate atomic data are required, including cross sections for collisional excitation and ionization, radiative rates, and the wavelengths and strengths of satellite lines. Although theoretical atomic models have been created to estimate many of the rates and cross sections involved, very few experimental results are available for comparison with theoretical predictions. This thesis describes an experimental study of heliumlike neon using an electron beam ion trap, a device specifically designed to study X-ray emission from highly charged ions. Using a low-energy X-ray spectrometer designed and built for this experiment, electron impact excitation cross sections and dielectronic satellite strengths were measured for all significant n = 2{yields}1 emission lines in He-like and Li-like Ne over a range of energy extending from well below the direct excitation threshold of the lines to over fourteen times the threshold energy. The cross section for innershell ionization of Li-like Ne, which excites the He-like forbidden line, was also measured. In addition, the radiative and collisional depopulation rates of the metastable ls2s {sup 3}S{sub 1}, state, which form the basis of the He-like Ne density diagnostic, were determined. Experimental results were generally in agreement with theoretical predictions, although some significant differences were noted, particularly for the wavelengths and resonance strengths of dielectronic satellites.

Wargelin, B.J.

1993-10-01

319

Laser-driven proton sources and their applications: femtosecond intense laser plasma driven simultaneous proton and x-ray imaging  

Microsoft Academic Search

We have performed simultaneous proton and X-ray imaging with an ultra-short and high-intensity Ti: Sap laser system. More than 1010 protons, whose maximum energy reaches 2.5 MeV, were delivered within a ~ps bunch. At the same time, keV X-ray is generated at almost the same place where protons are emitted. We have performed the simultaneous imaging of the copper mesh

M. Nishiuchi; H. Daido; A. Yogo; A. Sagisaka; K. Ogura; S. Orimo; M. Mori; J. Ma; A. S. Pirozhkov; H. Kiriyama; S. Kanazawa; S. Kondo; Y. Yamamoto; T. Shimoura; M. Tanoue; Y. Nakai; A. Akutsu; A. Nagashima; S. V. Bulanov; T. Z. Esirkepov; T. Kimura; T. Tajima; K. Nemoto; Y. Oishi; T. Nayuki; T. Fujii; A. Noda; Y. Iwashita; T. Shirai; S. Nakamura; I. W. Choi; T. J. Yu; J. H. Sung; H. T. Kim; T. M. Jeong; K.-H. Hong; Y.-C. Noh; D.-K. Ko; J. Lee

2008-01-01

320

Characteristics of a high-intensity plasma flash x-ray generator having a double-target radiation tube  

Microsoft Academic Search

The radiographic characteristics of a high-intensity plasma flash x-ray generator having a solid-target (anode) radiation tube are described. This generator consisted of the following essential components; a high- voltage power supply, a low-impedance coaxial transmission line, a coaxial oil condenser of 0.2 (mu) F, a turbo-molecular pump, a thyratron pulser as a trigger device, and a flash x-ray triode having

Eiichi Sato; Michiaki Sagae; Kei Takahashi; Teiji Oizumi; Yasuomi Hayasi; Yoshiharu Tamakawa; Toru Yanagisawa

1995-01-01

321

Beam splitting mirrors for miniature Fourier transform soft x-ray (FTXR) interferometer  

NASA Astrophysics Data System (ADS)

The development of Fourier Transform (FT) spectral techniques in the soft X-ray spectral region has been advocated in the past as a possible route to constructing a bench-top size spectral imager with high spatial and spectral resolution. The crux of the imager is a soft X-ray interferometer. Auxiliary subsystems include a wide-band soft X-ray source, focusing optics and detection systems. When tuned over a sufficiently large range of path delays, the interferometer will sinusoidally modulate the source spectrum centered at the core wavelength of interest, the spectrum illuminates a target, the reflected signal is imaged onto a CCD, and data acquired for different frames is converted to spectra in software by using FT methods similar to those used in IR spectrometry producing spectral image per each pixel. The use of shorter wavelengths results in dramatic increase in imaging resolution, the modulation across the beam width results in highly efficient use of the beam spectral content, facilitating construction of a bench-top instrument. With the predicted <0.1eV spectral and <100 nm spatial resolution, the imager would be able to map core-level shift spectra for elements such as Carbon, which can be used as a chemical compound fingerprint and imaging intracellular structures. We report on our progress in the development of a Fourier Transform X-ray (FTXR) interferometer. The enabling technology is X-ray beam splitting mirrors. The mirrors are not available commercially; multi layers of quarter-wave films (used in IR and visible) are not suitable, and several efforts by other researchers who used parallel slits met only a very limited success. In contrast, our beam splitters use thin (about 200 nm) SiN membranes perforated with a large number of very small holes prepared in our micro-fabrication laboratory at JPL. Precise control of surface roughness and high planarity are needed to achieve the requisite wave coherency. The beam splitters prepared-to-date had surface RMS and planarity better that <0.3 nm over a 0.45 mm x 1.4 mm area, meeting requirements for spectral imaging at 100eV. Efforts to improve the mirror flatness to a level required for core-level shifts of Carbon are under way.

Wilcox, Jaroslava; White, Victor; Shcheglov, Kirill; Kowalczyk, Robert

2010-08-01

322

Measurement of X-ray intensity in mammography by a ferroelectric dosimeter  

NASA Astrophysics Data System (ADS)

Each year in the US over 20 million women undergo mammography, a relatively high dose x-ray examination of the breast, which is relatively sensitive to the carcinogenic effect of ionizing radiation. The radiation risk from mammography is usually expressed in terms of mean glandular dose (MGD) which is calculated as the product of measured entrance exposure (ESE) and a dose conversion factor which is a function of anode material, peak tube voltage (23 to 35 kVp), half-value layer, filtration, compressed breast thickness and breast composition. Mammographic units may have anodes made of molybdenum, rhodium or tungsten and filters of molybdenum, rhodium, or aluminum. In order to accommodate all these parameters, multiple extensive tables of conversion factors are required to cover the range of possibilities. Energy fluence and energy imparted are alternative measures of radiation hazard, which have been used in situations where geometry or filtration is unconventional such as computed tomography or fluoroscopy. Unfortunately, at the present there is no way to directly measure these quantities clinically. In radiation therapy applications, calorimetry has been used to measure energy absorbed. A ferroelectric-based detector has been described that measures energy fluence rate (x-ray intensity) for diagnostic x-ray, 50 to 140 kVp, aluminum filtered tungsten spectrum [Carvalho & Alter: IEEE Transactions 44(6) 1997]. This work explores use of ferroelectric detectors to measure energy fluence, energy fluence rate and energy imparted in mammography. A detector interfaced with a laptop computer was developed to allow measurements on clinical units of five different manufactures having targets of molybdenum, rhodium and tungsten and filters of molybdenum, rhodium, and aluminum of various thicknesses. The measurements provide the first values of energy fluence and energy imparted in mammography. These measurements are compared with conventional parameters such as entrance exposure and mean glandular dose as well as published values of energy imparted for other types of x-ray examinations. Advantage of measuring dose in terms of energy imparted in mammography are simplicity of comparison with other sources of radiation exposure and potential (relative ease) of measurement across a variety of anode and filter combinations.

Alter, Albert J.

323

Ultrashort x-ray pulse generation by nonlinear Thomson scattering of a relativistic electron with an intense circularly polarized laser pulse  

NASA Astrophysics Data System (ADS)

The nonlinear Thomson scattering of a relativistic electron with an intense laser pulse is calculated numerically. The results show that an ultrashort x-ray pulse can be generated by an electron with an initial energy of 5 MeV propagating across a circularly polarized laser pulse with a duration of 8 femtosecond and an intensity of about 1.1×1021W/cm2, when the detection direction is perpendicular to the propagation directions of both the electron and the laser beam. The optimal values of the carrier-envelop phase and the intensity of the laser pulse for the generation of a single ultrashort x-ray pulse are obtained and verified by our calculations of the radiation characteristics.

Liu, F.; Willi, O.

2012-07-01

324

Optimization for Single-Spike X-Ray FELs at LCLS with a Low Charge Beam  

SciTech Connect

The Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron radiation sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup at 20 pC charge. In the soft x-ray regime, with combination of slotted-foil or undulator taper, a single spike x-ray pulse is achievable with peak FEL power of a few 10s GW. Linac Coherent Light Source (LCLS), the world's first hard x-ray Free electron laser (FEL), has started operation since 2009. With nominal operation charge of 250 pC, the generated x-ray pulse length is from 70 fs to a few hundred fs. This marks the beginning of a new era of ultrashort x-ray sciences. In addition, a low charge (20pC) operation mode has also been established. Since the collective effects are reduced at the low charge mode, we can increase the compression factor and still achieve a few kA peak current. The expected electron beam and x-ray pulses are less than 10 fs. There are growing interests in even shorter x-ray pulses, such as fs to sub-fs regime. One of the simple solutions is going to even lower charge. As discussed, single-spike x-ray pulses can be generated using 1 pC charge. However, this charge level is out of the present LCLS diagnostic range. 20 pC is a reasonable operation charge at LCLS, based on the present diagnostic system. At 20 pC in the soft x-ray wavelength regime, we have experimentally demonstrated that FEL can work at undercompression or over-compression mode, such as 1 degree off the full-compression; at full-compression, however, there is almost no lasing. In hard x-ray wavelength regime, we observed that there are reasonable photons generated even at full-compression mode, although the photon number is less than that from under-compression or over-compression mode. Since we cannot measure the x-ray pulse length at this time scale, the machine is typically optimized for generating maximum photons, not minimum pulse length. In this paper, we study the methods of producing femtosecond (or single-spike) x-ray pulses at LCLS with 20 pC charge, based on start-to-end simulations. Figure 1 shows a layout of LCLS. The compression in the second bunch compressor (BC2) determines the final e-beam bunch length. However, the laser heater, dog-leg after the main linac (DL2) and collective effects also affect the final bunch length. To adjust BC2 compression, we can either change the L2 phase or BC2 R{sub 56}. In this paper we only tune L2 phase while keep BC2 R{sub 56} fixed. For the start-to-end simulations, we used IMPACT-T and ELEGANT tracking from the photocathode to the entrance of the undulator, after that the FEL radiation was simulated with GENESIS. IMPACT-T tracks about 10{sup 6} particles in the injector part until 135 MeV, including 3D space charge force. The output particles from IMPACT-T are smoothed and increased to 12 x 10{sup 6} to reduce high-frequency numerical noise for subsequent ELEGANT simulations, which include linear and nonlinear transport effects, a 1D transient model of CSR, and longitudinal space charge effects, as well as geometric and resistive wake fields in the accelerator. In GENESIS part, the longitudinal wake field from undulator chamber and longitudinal space field are also included.

Wang, L.; Ding, Y.; Huang, Z.; /SLAC

2011-12-14

325

Size dependent ionization dynamics of argon clusters in intense x-ray pulses  

NASA Astrophysics Data System (ADS)

Free Electron Lasers open the door for novel experiments in many science areas ranging from ultrafast chemical dynamics to single shot imaging of molecules. For the success of virtually all experiments with free electron lasers a detailed understanding of the light - matter interaction in the x-ray regime is pivotal. The Linac Coherent Light Source (LCLS) free electron laser in Stanford allows for the first time to study innershell ionization dynamics of intense x-ray pulses on a femtosecond time scale. We performed experiments on the ionization dynamics of Argon clusters at different pulse length using the slotted spoiler foil in the second LCLS bunch compressor [1]. The Auger rate of argon clusters is predicted to be size dependent and lower than in atoms due to delocalization of the valence electrons [2]. We observe a dependence of the ionization dynamics on pulse length and cluster size. The results are discussed and also compared to recent atomic and molecular data from LCLS.[4pt] [1] P. Emma et al. PRL 92, 074801 (2004)[0pt] [2] U. Saalmann, JM Rost PRL 89, 14 (2002)

Schorb, Sebastian; Swiggers, M.; Coffee, R.; Messerschmidt, M.; Moeller, S.; Williams, G.; Bozek, J.; Osipov, T.; Wada, S.; Rupp, D.; Moeller, T.; Bostedt, C.

2011-03-01

326

Size dependent ionization dynamics of argon clusters in intense x-ray pulses  

NASA Astrophysics Data System (ADS)

Free Electron Lasers open the door for novel experiments in many science areas ranging from ultrafast chemical dynamics to single shot imaging of molecules. For the success of virtually all experiments with free electron lasers a detailed understanding of the light - matter interaction in the x-ray regime is pivotal. The Linac Coherent Light Source (LCLS) free electron laser in Stanford allows for the first time to study innershell ionization dynamics of intense x-ray pulses on a femtosecond time scale. We performed experiments on the ionization dynamics of Argon clusters at different pulse length using the slotted spoiler foil in the second LCLS bunch compressor [1]. The Auger rate of argon clusters is predicted to be size dependent and lower than in atoms due to delocalization of the valence electrons [2]. We observe a dependence of the ionization dynamics on pulse length and cluster size. The results are discussed and also compared to recent atomic and molecular data from LCLS.[4pt] [1] P. Emma et al. PRL 92, 074801 (2004)[0pt] [2] U. Saalmann, JM Rost PRL 89, 14 (2002)

Schorb, Sebastian; Rupp, D.; Swiggers, M.; Coffee, R. N.; Messerschmidt, M.; Williams, G.; Bozek, J. D.; Wada, S.-I.; Möller, T.; Bostedt, C.

2012-06-01

327

Size dependent ionization dynamics of argon clusters in intense x-ray pulses  

NASA Astrophysics Data System (ADS)

Free Electron Lasers open the door for novel experiments in many science areas ranging from ultrafast chemical dynamics to single shot imaging of molecules. For the success of virtually all experiments with free electron lasers a detailed understanding of the light - matter interaction in the x-ray regime is pivotal. The Linac Coherent Light Source (LCLS) free electron laser in Stanford allows for the first time to study inner shell ionization dynamics of intense x-ray pulses on a femtosecond time scale. We performed experiments on the ionization dynamics of Argon clusters at different pulse length using the slotted spoiler foil in the second LCLS bunch compressor [1]. The Auger rate of argon clusters is predicted to be size dependent and lower than in atoms due to delocalization of the valence electrons [2]. We observe a dependence of the ionization dynamics on pulse length and cluster size. The results are discussed and also compared to recent atomic and molecular data from LCLS.[4pt] [1] P. Emma et al. PRL 92, 074801 (2004)[0pt] [2] U. Saalmann, JM Rost, PRL 89, 14 (2002)

Schorb, Sebastian; Swiggers, M.; Rupp, D.; Coffee, R.; Messerschmidt, M.; Möller, S.; Williams, G.; Bozek, J.; Osipov, T.; Wada, S.; Kornilov, O.; Möller, T.; Bostedt, C.

2011-11-01

328

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

NASA Astrophysics Data System (ADS)

We propose and describe a microfluidic system for high intensity x-ray measurements. The required open access to a microfluidic channel is provided by an out-of-plane capillary burst valve (CBV). The functionality of the out-of-plane CBV is characterized with respect to the diameter of the windowless access hole, ranging from 10 to 130 ?m. Maximum driving pressures from 22 to 280 mbar corresponding to refresh rates of the exposed sample from 300 Hz to 54 kHz is demonstrated. The microfluidic system is tested at beamline ID09b at the ESRF synchrotron radiation facility in Grenoble, and x-ray scattering measurements are shown to be feasible and to require only very limited amounts of sample, <1 ml/h of measurements without recapturing of sample. With small adjustments of the present chip design, scattering angles up to 30° can be achieved without shadowing effects and integration on-chip mixing and spectroscopy appears straightforward.

Vig, Asger Laurberg; Haldrup, Kristoffer; Enevoldsen, Nikolaj; Thilsted, Anil Haraksingh; Eriksen, Johan; Kristensen, Anders; Feidenhans'l, Robert; Nielsen, Martin Meedom

2009-11-01

329

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser  

PubMed Central

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes.

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T.; Thomas, Richard D.; Larsson, Mats; Richter, Robert; Prince, Kevin C.; Bozek, John D.; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N.; Tashiro, Motomichi; Ehara, Masahiro

2011-01-01

330

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser.  

PubMed

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T; Thomas, Richard D; Larsson, Mats; Richter, Robert; Prince, Kevin C; Bozek, John D; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N; Tashiro, Motomichi; Ehara, Masahiro

2011-10-11

331

Controlling X-ray beam trajectory with a flexible hollow glass fibre  

PubMed Central

A metre-length flexible hollow glass fibre with 20?µm-bore and 1.5?mm-cladding diameters for transporting a synchrotron X-ray beam and controlling the trajectory has been examined. The large cladding diameter maintains a moderate curvature to satisfy the shallow glancing angle of total reflection. The observed transmission efficiency was more than 20% at 12.4?keV. As a demonstration, a wide-area scan of a synchrotron radiation beam was performed to identify the elements for a fixed metal film through its absorption spectra.

Tanaka, Yoshihito; Nakatani, Takashi; Onitsuka, Rena; Sawada, Kei; Takahashi, Isao

2014-01-01

332

Ultrashort hard X-ray pulse driven by cylindrical vector beam  

NASA Astrophysics Data System (ADS)

Maxwell equations determine that a shaped electromagnetic pulse in vacuum can be an azimuthally polarized (ap) cylindrical vector (CV) beam. High-order harmonics generation (HHG) by the ap-CV beam can effectively yield hard X-ray photons (??˜10 eV). By controlling relative positions of atoms to the axis of driving laser pulse, we can adjust the generated HHG spectrum and the temporal shape of the driven pulse. Calculations confirm that the duration of driven pulse can be achieved to sub-femtosecond level.

Lin, H.; Wang, C.; Liu, C. P.

2013-04-01

333

Calculation of the parameters of the X-ray diffraction station with adaptive segmented optics on the side beam from the wiggler of the Sibir'-2 storage ring  

SciTech Connect

The mounting of an X-ray diffraction station on the side beam of a 19-pole superconducting wiggler makes it possible not only to use the central synchrotron radiation beam with a wavelength of 0.5 Angstrom-Sign , but also to solve problems requiring softer X rays at a synchrotron radiation (SR) intensity exceeding that for the beams from the bending magnet. A numerical simulation of the formation of photon beams from a source and their transmission through the elements of the station (and through the station as a whole) allows one to calculate the parameters of the station, compare it with the existing analogs, determine its potential and actual efficiency of its elements, and estimate the adjustment quality. A numerical simulation of the SR source on the side beam from the wiggler and the focusing channel (segmented condenser mirror, monochromator with sagittal focusing by the segmented second crystal, and segmented focusing mirror) has been performed. The sizes of the focus and the divergence of rays in it are determined with allowance for the finite sizes of segments. The intensity of radiation with a wavelength {lambda} = 1.0 Angstrom-Sign in the focus is determined taking into account the loss in the SR extraction channel and in the focusing channel. The values of the critical wavelength for the side beam from the wiggler and the wavelength resolution are calculated. The intensities in the X-ray diffraction pattern and its angular resolution are found.

Molodenskii, D. S.; Kheiker, D. M., E-mail: kheiker@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Korchuganov, V. N. [National Research Center Kurchatov Institute (Russian Federation); Konoplev, E. E. [NPO Luch (Russian Federation); Dorovatovskii, P. V. [National Research Center Kurchatov Institute (Russian Federation)

2012-05-15

334

Soft X-Ray Magnetic Imaging of Focused Ion Beam Lithographically Patterned Fe Thin Films  

SciTech Connect

We illustrate the potential of modifying the magnetic behavior and structural properties of ferromagnetic thin films using focused ion beam 'direct-write' lithography. Patterns inspired by the split-ring resonators often used as components in meta-materials were defined upon 15 nm Fe films using a 30 keV Ga{sup +} focused ion beam at a dose of 2 x 10{sup 16} ions cm{sup -2}. Structural, chemical and magnetic changes to the Fe were studied using transmission soft X-ray microscopy at the ALS, Berkeley CA. X-ray absorption spectra showed a 23% reduction in the thickness of the film in the Ga irradiated areas, but no change to the chemical environment of Fe was evident. X-ray images of the magnetic reversal process show domain wall pinning around the implanted areas, resulting in an overall increase in the coercivity of the film. Transmission electron microscopy showed significant grain growth in the implanted regions.

Cook, Paul J.; Shen, Tichan H.; Grundy, PhilJ.; Im, Mi Young; Fischer, Peter; Morton, Simon A.; Kilcoyne, Arthur D.L.

2008-11-09

335

Heat transfer issues in high-heat-load synchrotron x-ray beams  

SciTech Connect

In this paper, a short description of the synchrotron radiation x-ray sources and the associated power loads is given, followed by a brief description of typical synchrotron components and their heat load. It is emphasized that the design goals for most of these components is to limit (a) temperature, (b) stresses, or (c) strains in the system. Each design calls for a different geometry, material selection, and cooling scheme. Cooling schemes that have been utilized so far are primarily single phase and include simple macrochannel cooling, microchannel cooling, contact cooling, pin-post cooling, porous-flow cooling, jet cooling, etc. Water, liquid metals, and various cryogenic coolants have been used. Because the trend in x-ray beam development is towards brighter (i.e., more powerful) beams and assuming that no radical changes in the design of x-ray generating machines occurs in the next few years, it is fair to state that the utilization of various effective cooling schemes and, in particular, two-phase flow (e.g., subcooled boiling) warrants further investigation. This, however, requires a thorough examination of stability and reliability of two-phase flows for high-heat-flux components operating in ultrahigh vacuum with stringent reliability requirements.

Khounsary, A.M.; Mills, D.M.

1994-09-01

336

Image observation of diffraction spots using FZP and coherent X-ray beam  

SciTech Connect

New small angle X-ray dispersion speckle method by the condensing optical system using FZP (Fresnel zone plate) was performed. And single crystal diffraction spot image was observed using this optical system. High photon flux with the FZP of 100-micron-diameter is obtained than that with a 5-micron-diameter pinhole. S/N ratio of data improved and measurement time also became short. The minimum beam size focused with the FZP was 0.25 {mu}m. The speckle image resulting from the non-ordering structure and periodic structure of 10nm order is successfully observed. This optical system was applicable also to diffraction spot image observation. We show a possibility that the information of the periodic and/or random structural analysis with sub-{mu}m order which were unsuitable with the conventional single crystal x-ray diffraction analysis.

Suzuki, Takuya; Yoshizuka, Kazuharu [Faculty of Environmental Engineering, The University of Kitakyushu, 1-1 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka, 808-0135 (Japan); Takano, Hidekazu [College of Humanities and Sciences, Nippon University, 3-25-40 sakurazyousui, Setagaya-ku, Tokyo, 156-8550 (Japan); Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio [JASRI/SPring-8, 1-1-1 Kouto Mikazuki-cho Sayo-gun Hyogo 679-5198 (Japan); Kohmura, Yoshiki [RIKEN/SPring-8, 1-1-1 Kouto Mikazuki-cho Sayo-gun Hyogo 679-5148 (Japan); Hasegawa, Masashi [Institute for Materials Research, Tohoku University, 2-1-1 Aobaku Katahira, Sendai, 980-8577 (Japan)

2004-05-12

337

100 kV GHOST electron beam proximity correction on tungsten x-ray masks  

SciTech Connect

100 kV electron beam exposures of tungsten x-ray masks have been made using GHOST proximity correction. 0.15 [mu]m lithography is possible on masks having a 0.3 [mu]m thick tungsten absorber. 0.25 [mu]m features are resolved on masks with a 0.6 [mu]m tungsten film thickness. The linewidth control ([plus minus]5%) and dose latitude (2.5 nm edge shift per 1% dose change) are as good or better than those obtained by dose modulation, and contrast is sufficiently high to permit dry etch pattern transfer into the tungsten absorber. The process latitude makes 100 kV GHOST exposures suitable for patterning 1 Gbit dynamic random access memories on 1m x-ray masks.

Gesley, M.A. (Etec Systems, Inc., Hayward, California 94545 (United States)); McCord, M.A. (IBM Semiconductor Research and Development Center, P.O. Box 218, Yorktown Heights, New York 10598 (United States))

1994-11-01

338

Chemically assisted focused-ion-beam etching for tungsten x-ray mask repair  

NASA Astrophysics Data System (ADS)

Finely focused ion beams have been used for repair of defects in photomasks and X-ray masks either by sputter removal of excess absorber material or by deposition of new absorber material. These mask structures employ polycrystalline metal absorbers with grain sizes in the 0.1 micrometers range. As feature dimensions are pushed downward, the effects of these grains become more important. A great deal of roughness can occur during FIB sputter removal of excess absorber for defect repair due to ion channeling and the resulting spatially nonuniform sputtering. In this paper, we describe a method for reducing the roughness in defect repair for Tungsten X-ray masks using chemically assisted FIB etching and a Cr/W/Cr multilayer mask structure.

Harriott, Lloyd R.; Kola, R. R.; Celler, George K.

1993-06-01

339

Beam hardening effects in grating-based x-ray phase-contrast imaging  

SciTech Connect

Purpose: In this work, the authors investigate how beam hardening affects the image formation in x-ray phase-contrast imaging and consecutively develop a correction algorithm based on the results of the analysis. Methods: The authors' approach utilizes a recently developed x-ray imaging technique using a grating interferometer capable of visualizing the differential phase shift of a wave front traversing an object. An analytical description of beam hardening is given, highlighting differences between attenuation and phase-contrast imaging. The authors present exemplary beam hardening artifacts for a number of well-defined samples in measurements at a compact laboratory setup using a polychromatic source. Results: Despite the differences in image formation, the authors show that beam hardening leads to a similar reduction of image quality in phase-contrast imaging as in conventional attenuation-contrast imaging. Additionally, the authors demonstrate that for homogeneous objects, beam hardening artifacts can be corrected by a linearization technique, applicable to all kinds of phase-contrast methods using polychromatic sources. Conclusions: The evaluated correction algorithm is shown to yield good results for a number of simple test objects and can thus be advocated in medical imaging and nondestructive testing.

Chabior, Michael; Donath, Tilman; David, Christian; Bunk, Oliver; Schuster, Manfred; Schroer, Christian; Pfeiffer, Franz [Siemens AG Corporate Technology, 80200 Muenchen (Germany); Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Siemens AG Corporate Technology, 80200 Muenchen (Germany); Technische Universitaet Dresden, 01062 Dresden (Germany); Technische Universitaet Muenchen, 85748 Garching (Germany)

2011-03-15

340

Design of x-ray diagnostic beam line for a synchrotron radiation source and measurement results  

NASA Astrophysics Data System (ADS)

Indus-2 is a 2.5 GeV synchrotron radiation source (SRS) operational at the Raja Ramanna Centre for Advanced Technology (RRCAT) in India. We have designed, developed and commissioned x-ray diagnostic beam line (X-DBL) at the Indus-2. It is based on pinhole array imaging (8-18 keV). We have derived new equations for online measurements of source position and emission angle with pinhole array optics. Measured values are compared with the measurements at an independent x-ray beam position monitor (staggered pair blade monitor) installed in the X-DBL. The measured values are close to the theoretical expected values within ±12 ?m (or ±1.5 ?rad) for sufficiently wide range of the beam movements. So, beside the beam size and the beam emittance, online information for the vertical position and angle is also used in the orbit steering. In this paper, the various design considerations of the X-DBL and online measurement results are presented.

Garg, Akash Deep; Karnewar, A. K.; Ojha, A.; Shrivastava, B. B.; Holikatti, A. C.; Puntambekar, T. A.; Navathe, C. P.

2014-08-01

341

Residual Stresses Measurements by Means of X Ray Diffraction on Electron Beam Welded Joints and Laser Hardened Surfaces.  

National Technical Information Service (NTIS)

X ray diffraction techniques are applied to the evaluation of residual stresses induced by two metallurgical processes: electron beam welding (EBW) and laser surface hardening (LSH) on low alloy steel of aeronautical interest. This technique is shown to b...

G. P. Mor R. Pezzoni

1989-01-01

342

Generation of strongly coupled Xe cluster nanoplasmas by low intensive soft x-ray laser irradiation  

SciTech Connect

A seeding gas jet including Xe clusters was irradiated with a laser-driven plasma soft x-ray laser pulse ({lambda}=13.9 nm, {approx}7 ps, {<=}5 Multiplication-Sign 10{sup 9} W/cm{sup 2}), where the laser photon energy is high enough to ionize 4d core electrons. In order to clarify how the innershell ionization followed by the Auger electron emission is affected under the intense laser irradiation, the electron energy distribution was measured. Photoelectron spectra showed that the peak position attributed to 4d hole shifted to lower energy and the spectral width was broadened with increasing cluster size. Moreover, the energy distribution exhibited that a strongly coupled cluster nanoplasma with several eV was generated.

Namba, S.; Hasegawa, N.; Kishimoto, M.; Nishikino, M.; Kawachi, T. [Graduate School of Engineering, Hiroshima University,Kagamiyama 1-4-1, Higashi-Hiroshima, Hiroshima, 739-8527 (Japan); Quantum Beam Science Directorate, Japan Atomic Energy Agency, Umemidai 8-1, Kizugawa, Kyoto, 619-0215 (Japan)

2012-07-11

343

Hard x-ray production from high intensity laser solid interactions  

SciTech Connect

Intense laser (> 10{sup 21} W/cm{sup 2}) driven hard x-ray sources offer a new alternative to conventional electron accelerator bremsstrahlung sources. These laser driven sources offer considerable simplicity in design and cost advantage for multiple axis views and have the potential for much higher spatial and temporal resolution than is achievable with accelerator sources We have begun a series of experiments using the Petawatt Laser system at LLNL to determine the potential of these sources for radiography applications Absolutely calibrated spectra extending to 20 MeV and high resolution radiographs through a {rho}r{>=}150 gm/cm{sup 2} have been obtained The physics of these sources and the scaling relationships and laser technology required to provide the dose levels necessary for radiography applications will be discussed Diagnostics of the laser produced electrons and photons will be addressed

Sefcik, J. A., LLNL

1998-06-03

344

X-ray Intensity Fluctuation Spectroscopy Studies of Dynamics of Block Copolymers in Selective Solvents  

NASA Astrophysics Data System (ADS)

We investigated the dynamics of a block copolymer SEBS (triblock of styrene (S) and ethylene-butylene, EB) in selective solvents using X-ray Intensity Fluctuation Spectroscopy (XIFS). We examined the temperature dependence of dynamics in cylindrical, spherical and lamellar phases as well as in coexisting phases through the transitions. We were able to observe dynamics in hexagonally-packed-cylinders (HEX) and body-centered-cubic (BCC) phases in 45% SEBS in mineral oil as well as HEX and lamellar (LAM) phases in 40% SEBS in dibutyl phthalate (selective to S). We observed two exponentially decaying dynamic modes in coexisting HEX and BCC phases, and in coexisting LAM and HEX phases. While the slower mode has a q-independent decay rate, the faster mode's decay rate decreases with increasing q, consistent with the well-known deGennes narrowing as q varies through a structural peak

Liu, Yongsheng; Spring, Julian; Ludwig, Karl; Bansil, Rama

2010-03-01

345

Electron-relocalization dynamics in xenon clusters in intense soft-x-ray fields  

NASA Astrophysics Data System (ADS)

Intense and temporally structured x-ray laser fields enable the controlled generation of strongly coupled nonequilibrium cluster nanoplasmas and the time-resolved investigation of their dynamics. Recent femtosecond pump-probe experiments on xenon clusters revealed subpicosecond relaxation dynamics in the cluster nanoplasma via delay-dependent charge states of emitted atomic ions [M. Krikunova et al., J. Phys. B: At. Mol. Opt. Phys. 45, 105101 (2012), 10.1088/0953-4075/45/10/105101]. Here we report a scheme based on local electron single-particle energy spectra that enables microscopic tracing of the underlying electron-relocalization processes in molecular dynamics simulations up to the strong-coupling regime. We find more efficient recombination in the cluster core and delay-dependent ion charge states, in good agreement with experiments. Our method is applicable to any particle-based plasma simulation and expected to offer insights into correlated relaxation processes in inhomogenous, strongly coupled plasmas.

Arbeiter, Mathias; Peltz, Christian; Fennel, Thomas

2014-04-01

346

Point spread function measurement of an X-ray beam focused by a multilayer zone plate with narrow annular aperture.  

PubMed

The experimental procedure for obtaining the point spread function (PSF) of a focusing beam generated using an X-ray multilayer zone plate (MZP) with a narrow annular aperture has been developed. It was possible to reconstruct the PSF by applying the tomographic process to the measured dataset consisting of line spread functions (LSFs) in every radial direction on the focal plane. The LSFs were measured by a knife-edge scanning method of detecting scattered intensity. In the experimental work, quasi-monochromatic undulator radiation with a first harmonic energy of 20?keV was directly focused without a monochromator by the MZP, and the PSF was measured using this procedure. As a result, a near diffraction-limited focused beam size of 46?nm full width at half-maximum was obtained. PMID:24562567

Takano, Hidekazu; Konishi, Shigeki; Koyama, Takahisa; Tsusaka, Yoshiyuki; Ichimaru, Satoshi; Ohchi, Tadayuki; Takenaka, Hisataka; Kagoshima, Yasushi

2014-03-01

347

Time-resolved investigation of nanometer scale deformations induced by a high flux x-ray beam  

NASA Astrophysics Data System (ADS)

We present results of a time-resolved pump-probe experiment where a Si sample was exposed to an intense 15 keV beam and its surface monitored by measuring the wavefront deformation of a reflected optical laser probe beam. By reconstructing and back propagating the wavefront, the deformed surface can be retrieved for each time step. The dynamics of the heat bump, build-up and relaxation, is followed with a spatial resolution in the nanometer range. The results are interpreted taking into account results of finite element method simulations. Due to its robustness and simplicity this method should find further developments at new x-ray light sources (FEL) or be used to gain understanding on thermo-dynamical behavior of highly excited materials.

Gaudin, J.; Keitel, B.; Jurgilaitis, A.; Nüske, R.; Guérin, L.; Larsson, J.; Mann, K.; Schäfer, B.; Tiedtke, K.; Trapp, A.; Tschentscher, Th.; Yang, F.; Wulff, M.; Sinn, H.; Flöter, B.

2011-08-01

348

Experimental and theoretical studies of the physical processes occurring in thin plane targets irradiated by intense X-ray pulses  

NASA Astrophysics Data System (ADS)

Results are presented from experimental and theoretical studies of the interaction of intense X-ray pulses with different types of plane targets, including low-density (˜10 mg/cm3) ones, in the Angara-5-1 facility. It is found experimentally that a dense low-temperature plasma forms on the target surface before the arrival of the main heating X-ray pulse. It is demonstrated that the contrast of the X-ray pulse can be increased by placing a thin organic film between the target and the discharge gap. The expansion velocity of the plasma created on the target surface irradiated by Z-pinch-produced X rays was found to be (3 4) × 106 cm/s. A comparison between the simulation and experimental results confirms the validity of the physical-mathematical model used.

Bugrov, A. É.; Burdonski?, I. N.; Gavrilov, V. V.; Gol'Tsov, A. Yu.; Grabovski?, E. V.; Efremov, V. P.; Zhuzhukalo, E. V.; Zurin, M. V.; Koval'Ski?, N. G.; Kondrashov, V. N.; Ole?nik, G. M.; Potapenko, A. I.; Samokhin, A. A.; Smirnov, V. P.; Fortov, V. E.; Frolov, I. N.

2007-06-01

349

Experimental and theoretical studies of the physical processes occurring in thin plane targets irradiated by intense X-ray pulses  

SciTech Connect

Results are presented from experimental and theoretical studies of the interaction of intense X-ray pulses with different types of plane targets, including low-density ({approx}10 mg/cm{sup 3}) ones, in the Angara-5-1 facility. It is found experimentally that a dense low-temperature plasma forms on the target surface before the arrival of the main heating X-ray pulse. It is demonstrated that the contrast of the X-ray pulse can be increased by placing a thin organic film between the target and the discharge gap. The expansion velocity of the plasma created on the target surface irradiated by Z-pinch-produced X rays was found to be (3-4) x 10{sup 6} cm/s. A comparison between the simulation and experimental results confirms the validity of the physical-mathematical model used.

Bugrov, A. E.; Burdonskii, I. N.; Gavrilov, V. V.; Gol'tsov, A. Yu.; Grabovskii, E. V. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Efremov, V. P. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation); Zhuzhukalo, E. V.; Zurin, M. V.; Koval'skii, N. G.; Kondrashov, V. N.; Oleinik, G. M. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Potapenko, A. I. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation); Samokhin, A. A.; Smirnov, V. P. [Troitsk Institute for Innovation and Fusion Research (Russian Federation); Fortov, V. E. [Russian Academy of Sciences, Institute for High Energy Densities, Joint Institute for High Temperatures (Russian Federation); Frolov, I. N. [Troitsk Institute for Innovation and Fusion Research (Russian Federation)

2007-06-15

350

First detection of correlated electron beams and plasma jets in radio and soft x-ray data  

NASA Astrophysics Data System (ADS)

From a common analysis of solar radio spectral and imaging data of a fast drift burst of type U(N) together with Yohko soft X-ray images it is shown that the radio emission is compatible with electron beams injected and reflected in extended loops. The electron beam production concides with the injection of hot matter, visible as a jetlike soft X-ray feature in the underlying loop system. the underlying loop system.

Aurass, H.; Klein, K.-L.; Martens, P. C. H.

1994-11-01

351

A short pulse X-ray generation via Thomson scattering of ultrashort laser pulses by relativistic electron beams  

Microsoft Academic Search

Short pulsed X-rays were experimentally generated by 90° Thomson scatterings of 2 TW, 90 fs laser pulses by 17 MeV electron beams. Synchronization between the laser pulses and electron beams were achieved within a few ps. A 100 fs X-ray pulse will be generated via backward Thomson scatterings from a 100 fs electron bunch made by a bunch compression chicane.

K. Nakajima; H. Nakanishi; A. Ogata; H. Kotaki; H. Ahn; H. Dewn; M. Kando; S. Kondoh; F. Sakai; T. Watanabe; T. Ueda; M. Uesaka

1997-01-01

352

Effects of Surface Processing on the Response of CZT Gamma Detectors: Studies with a Collimated Synchrotron X-Ray Beam  

Microsoft Academic Search

Using a microscale X-ray mapping technique incorporating a synchrotron beam, we are able to reveal the fine details of the\\u000a surface properties in cadmium zinc telluride (CZT) semiconductor detectors. A detector, with various degrees of surface roughness,\\u000a was irradiated by a high-spatial-resolution X-ray beam. The detector’s response was analyzed and displayed as a two-dimensional\\u000a (2-D) map, and the charge collection

A. Hossain; A. E. Bolotnikov; G. S. Camarda; Y. Cui; S. Babalola; A. Burger; R. B. James

2008-01-01

353

Status and Prospects on Soft X-Ray Lasers Seeded by a High Harmonic Beam at LOA  

Microsoft Academic Search

Thanks to the most recent works on x-ray laser and on high order harmonics (HHG), it is now possible to produce an energetic\\u000a beam having at the same time the required optical properties. The solution consists in seeding the XRL amplifier medium with\\u000a another beam (HHG). This experiment was successfully realized in LOA. We studied seeding of two x-ray laser

S. Sebban; Ph. Zeitoun; G. Faivre; S. Hallou; A. S. Morlens; J. P. Goddet; B. Cros; G. Vieux; G Maynard; T. Mocek; M. Kozlová; J. P. Causmes; H. Merdji

354

Study of the formalism used to determine the absorbed dose for low-energy x-ray beams  

Microsoft Academic Search

We have studied the procedure commonly recommended by dosimetry protocols for the determination of the absorbed dose in water for low-energy x-rays beams, generated with potentials up to 150 kVp. X-ray beams with different spectra obtained with the XCOMP5R code were transported using the Monte Carlo code PENELOPE in order to calculate backscatter factors and mass-energy absorption coefficients. We have

U. Chica; M. Anguiano; A. M. Lallena

2008-01-01

355

Coherence properties of focused X-ray beams at high-brilliance synchrotron sources  

PubMed Central

An analytical approach describing properties of focused partially coherent X-ray beams is presented. The method is based on the results of statistical optics and gives both the beam size and transverse coherence length at any distance behind an optical element. In particular, here Gaussian Schell-model beams and thin optical elements are considered. Limiting cases of incoherent and fully coherent illumination of the focusing element are discussed. The effect of the beam-defining aperture, typically used in combination with focusing elements at synchrotron sources to improve transverse coherence, is also analyzed in detail. As an example, the coherence properties in the focal region of compound refractive lenses at the PETRA III synchrotron source are analyzed.

Singer, Andrej; Vartanyants, Ivan A.

2014-01-01

356

Mean mass energy absorption coefficient ratios for megavoltage x-ray beams.  

PubMed

Mean mass energy absorption coefficient ratios of acrylic, polystyrene, and water to air, were calculated using Monte Carlo generated energy spectra. The energy spectra were calculated for 4- to 50-MV x-ray beams, from machines using flattening filters and scanning beams. The validity of these spectra was verified by comparing the measured ionization ratios with the calculated values. The agreement was found to be within 1.9%. For beams of energy below 6 MV, our estimates of the mean mass energy absorption coefficient ratios agree well with those recommended by the TG-21 protocol. For higher energy beams, the discrepancy increases to about 3%. It was found that the discrepancy is attributable to the different spectra used in these calculations. PMID:7643787

Furhang, E E; Chui, C S; Lovelock, M

1995-05-01

357

Effect on Particle Size to Emitted X-Ray Intensity in Pellet Cement Sample Analyzed with WDXRF Spectrometer  

Microsoft Academic Search

The particle size and heterogeneity effects on the analyte line were investigated for the analysis of powdered samples by X-ray fluorescence technique. In the analysis of samples utilizing the powder method, these effects caused serious errors with variations in particle size for the emitted intensity. The fluorescence intensities of some elements in pellet samples of cement (the range of particle

Faruk Demir; Onder Simsek; Gokhan Budak; Abdulhalik Karabulut

2008-01-01

358

Beam hardening: Analytical considerations of the effective attenuation coefficient of x-ray tomography  

SciTech Connect

Polychromatic x-ray beams traveling though material are prone to beam hardening, i.e., the high energy part of the incident spectrum gets over represented when traveling farther into the material. This study discusses the concept of a mean attenuation coefficient in a formal way. The total energy fluence is one-to-one related to the traveled distance in case of a polychromatic beam moving through a given, inhomogeneous material. On the basis of this one-to-one relation, it is useful to define a mean attenuation coefficient and study its decrease with depth. Our results are based on a novel parametrization of the energy dependence of the attenuation coefficient that allows for closed form evaluation of certain spectral integrals. This approach underpins the ad hoc semianalytical expressions given in the literature. An analytical model for the average attenuation coefficient is proposed that uses a simple fit of the attenuation coefficient as a function of the photon energy as input. It is shown that a simple extension of this model gives a rather good description of beam hardening for x-rays traveling through water.

Alles, J.; Mudde, R. F. [Kramers Laboratorium voor Fysische Technology, Department of Multi-Scale Physics, Delft University of Technology, Pr. Bernhardlaan 6, 2628 Delft (Netherlands)

2007-07-15

359

An MCNP-based model of a linear accelerator x-ray beam  

NASA Astrophysics Data System (ADS)

The Monte Carlo N-Particle radiation transport computer code (MCNP) has been employed on a personal computer to develop a simple model simulating the major components within the beam path of a linear accelerator radiation head, namely the electron target, primary conical collimator, beam flattening filter, wedge filter and the secondary collimators. The model was initially used to calculate the energy spectra and angular distributions of the x-ray beam for the Philips SL 75/5 linear accelerator, in a plane immediately beneath the flattening filter. These data were subsequently used as a `source' of x-rays at the target position, to assess the emergent beam from the secondary collimators. The depth dose distributions and dose profiles at constant depth for various field sizes have been calculated for a nominal operating potential of 4 MV and found to be within acceptable limits. It is concluded that the technique may be used to calculate the energy spectra of any linear accelerator upon specification of the component dimensions, materials and nominal accelerating potential. It is anticipated that this work will serve as the basis of a quality control tool for linear accelerators and treatment planning systems.

Lewis, R. D.; Ryde, S. J. S.; Hancock, D. A.; Evans, C. J.

1999-05-01

360

Energy distribution measurement of narrow-band ultrashort x-ray beams via K-edge filters subtraction  

SciTech Connect

The characterization of novel x-ray sources includes the measurement of the photon flux and the energy distribution of the produced beam. The aim of BEATS2 experiment at the SPARC-LAB facility of the INFN National Laboratories of Frascati (Rome, Italy) is to investigate possible medical applications of an x-ray source based on Thomson relativistic back-scattering. This source is expected to produce a pulsed quasi-monochromatic x-ray beam with an instantaneous flux of 10{sup 20} ph/s in pulses 10 ps long and with an average energy of about 20 keV. A direct measurement of energy distribution of this beam is very difficult with traditional detectors because of the extremely high photon flux. In this paper, we present a method for the evaluation of the energy distribution of quasi-monochromatic x-ray beams based on beam filtration with K-edge absorbing foils in the energy range of interest (16-22 keV). The technique was tested measuring the energy distribution of an x-ray beam having a spectrum similar to the expected one (SPARC-LAB Thomson source) by using a tungsten anode x-ray tube properly filtered and powered. The energy distribution obtained has been compared with the one measured with a HPGe detector showing very good agreement.

Cardarelli, Paolo; Di Domenico, Giovanni; Marziani, Michele; Mucollari, Irena; Pupillo, Gaia; Sisini, Francesco; Taibi, Angelo; Gambaccini, Mauro [Dipartimento di Fisica, Universita di Ferrara and INFN - Ferrara, via Saragat 1, I-44122 Ferrara (Italy)

2012-10-01

361

Energy distribution measurement of narrow-band ultrashort x-ray beams via K-edge filters subtraction  

NASA Astrophysics Data System (ADS)

The characterization of novel x-ray sources includes the measurement of the photon flux and the energy distribution of the produced beam. The aim of BEATS2 experiment at the SPARC-LAB facility of the INFN National Laboratories of Frascati (Rome, Italy) is to investigate possible medical applications of an x-ray source based on Thomson relativistic back-scattering. This source is expected to produce a pulsed quasi-monochromatic x-ray beam with an instantaneous flux of 1020 ph/s in pulses 10 ps long and with an average energy of about 20 keV. A direct measurement of energy distribution of this beam is very difficult with traditional detectors because of the extremely high photon flux. In this paper, we present a method for the evaluation of the energy distribution of quasi-monochromatic x-ray beams based on beam filtration with K-edge absorbing foils in the energy range of interest (16-22 keV). The technique was tested measuring the energy distribution of an x-ray beam having a spectrum similar to the expected one (SPARC-LAB Thomson source) by using a tungsten anode x-ray tube properly filtered and powered. The energy distribution obtained has been compared with the one measured with a HPGe detector showing very good agreement.

Cardarelli, Paolo; Di Domenico, Giovanni; Marziani, Michele; Muçollari, Irena; Pupillo, Gaia; Sisini, Francesco; Taibi, Angelo; Gambaccini, Mauro

2012-10-01

362

The Beynon Gabor zone plate: a new tool for de Broglie matter waves and hard X-rays? An off axis and focus intensity investigation.  

PubMed

Optical elements based on Fresnel zones are used in a range of applications, from X-ray telescopy to microscopy and recently also in the manipulation of de Broglie matter waves. In 1992 Beynon and co-workers presented a binary Gabor type zone plate (henceforth referred to as the Beynon Gabor zone plate). Because this zone plate has no higher order foci, it is in principle a very attractive candidate for focusing of de Broglie matter waves and in some cases X-rays. So far the Beynon Gabor zone plate investigations presented in the literature have concentrated on the intensity distribution along the optical axis and in the focal plane. Here we present a detailed numerical investigation of the Beynon Gabor zone plate, including an investigation of the off-optical axis, off focal plane intensity distribution for point source illumination. We show that at integer fractions of the focal length, the beam becomes nearly toroidal (doughnut-shaped). This offers potentially interesting new possibilities for de Broglie matter wave and X-ray optics, for example in STED-like applications. We further show that the increased intensity at the focal point predicted in the literature for a particular Beynon Gabor zone plate transmission function configuration is an artifact due to the lack of sampling nodes. We support our calculations with experimental measurements in the visible light range, using a Beynon Gabor zone plate fabricated with electron beam lithography. PMID:24514360

Greve, Martin M; Vial, Alexandre M; Stamnes, Jakob J; Holst, Bodil

2013-11-18

363

Intense Super-radiant X-rays from a Compact Source using a Nanocathode Array and Emittance Exchange  

SciTech Connect

A novel method of producing intense short wavelength radiation from relativistic electrons is described. The electrons are periodically bunched at the wavelength of interest enabling in-phase super-radiant emission that is far more intense than from unbunched electrons. The periodic bunching is achieved in steps beginning with an array of beamlets emitted from a nanoengineered field emission array. The beamlets are then manipulated and converted to a longitudinal density modulation via a transverse to longitudinal emittance exchange. Periodic bunching at short wavelength is shown to be possible, and the partially coherent x-ray properties produced by Inverse Compton scattering from an intense laser are estimated. The proposed method increases the efficiency of x-ray production by several orders of magnitude, potentially enabling compact x-ray sources to produce brilliance and flux similar to major synchrotron facilities.

Graves, W.S.; /MIT, LNS; Kaertner, F.X.; /MIT, LNS /CFEL, Hamburg; Moncton, D.E.; /MIT, LNS; Piot, P.; /Northern Illinois U. /Fermilab

2012-02-01

364

X-ray quantitative analysis of coal by the Reference Intensity Method. Final report  

Microsoft Academic Search

Twenty-four coal samples representing the four major rank types were analyzed by the x-ray RIM methodology which includes mass absorption analysis by x-ray transmission and quantitative x-ray powder diffraction. Twenty-three separate mineral species were observed in the samples, many of which could be quantified in the whole coal analysis. Several mineral species at levels of 5 wt % or less

B. L. Davis; L. R. Johnson; T. Mebrahtu

1986-01-01

365

Beamline, experimental stations and photon beam diagnostics for the hard x-ray free electron laser of SACLA  

NASA Astrophysics Data System (ADS)

A beamline for the x-ray free electron laser (XFEL) of SPring-8 Angstrom Compact free electron LAser (SACLA) provides hard x-ray pulses in the range 4.5-19.5 keV. Its optical system in an optics hutch delivers a pink beam below 15 keV with either of two double-mirror systems or a monochromatic beam with a double-crystal monochromator. These XFEL beams are used for various types of measurement at experimental stations, e.g. x-ray diffraction, coherent diffraction imaging, x-ray spectroscopy and pump-and-probe measurement. The experimental stations consist of experimental hutches and control stations, and a femtosecond optical laser which is synchronized with XFEL pulses. Photon diagnostics have been performed for measuring radiation parameters in a shot-by-shot manner.

Tono, K.; Togashi, T.; Inubushi, Y.; Sato, T.; Katayama, T.; Ogawa, K.; Ohashi, H.; Kimura, H.; Takahashi, S.; Takeshita, K.; Tomizawa, H.; Goto, S.; Ishikawa, T.; Yabashi, M.

2013-08-01

366

Probing the transverse coherence of an undulator x-ray beam using brownian particles.  

PubMed

We present a novel method to map the two-dimensional transverse coherence of an x-ray beam using the dynamical near-field speckles formed by scattering from colloidal particles. Owing to the statistical nature of the method, the coherence properties of synchrotron radiation from an undulator source is obtained with high accuracy. The two-dimensional complex coherence function is determined at the sample position and the imaging optical scheme further allowed us to evaluate the coherence factor at the undulator output despite the aberrations introduced by the focusing optics. PMID:20365931

Alaimo, M D; Potenza, M A C; Manfredda, M; Geloni, G; Sztucki, M; Narayanan, T; Giglio, M

2009-11-01

367

Image Covariance and Lesion Detectability in Direct Fan-Beam X-Ray Computed Tomography  

PubMed Central

We consider noise in computed tomography images that are reconstructed using the classical direct fan-beam filtered backprojection algorithm, from both full and short-scan data. A new, accurate method for computing image covariance is presented. The utility of the new covariance method is demonstrated by its application to the implementation of a channelized Hotelling observer for a lesion detection task. Results from the new covariance method and its application to the channelized Hotelling observer are compared with results from Monte Carlo Simulations. In addition, the impact of a bowtie filter and x-ray tube current modulation on reconstruction noise and lesion detectability are explored for full-scan reconstruction.

Wunderlich, Adam; Noo, Frederic

2009-01-01

368

Soft x-ray lasers seeded by a high harmonic beam  

NASA Astrophysics Data System (ADS)

We studied seeding of two x-ray laser transitions, 4d-4p at 32.8 nm in Kr8+ and 5d-5p 41.8 nm in Xe8+. The amplifying medium is generated by focussing a high energy circularly polarized, 35 fs 10 Hz Ti: sapphire laser system in a few mm cell filled with gas (xenon or krypton).We succeeded to increase from a factor 10 to 200 the input HHG energy, without deteriorating their optical qualities. The resulting beam was polarized, coherent and we estimate the output energy to be about 1 ?J.

Sebban, S.; Zeitoun, Ph.; Faivre, G.; Mocek, T.; Fajardo, M.; Kazamias, S.; Cros, B.; Vieux, G.; Maynard, G.

2005-09-01

369

Pulse-periodic generation of supershort avalanche electron beams and X-ray emission  

NASA Astrophysics Data System (ADS)

Pulse-periodic generation of supershort avalanche electron beams (SAEBs) and X-ray emission in nitrogen, as well as the transition from a single-pulse mode to a pulse-periodic mode with a high repetition frequency, was studied experimentally. It is shown that, in the pulse-periodic mode, the full width at halfmaximum of the SAEB is larger and the decrease rate of the gap voltage is lower than those in the single-pulse mode. It is found that, when the front duration of the voltage pulse at a nitrogen pressure of 90 Torr decreases from 2.5 to 0.3 ns, the X-ray exposure dose in the pulse-periodic mode increases by more than one order of magnitude and the number of SAEB electrons also increases. It is shown that, in the pulse-periodic mode of a diffuse discharge, gas heating in the discharge gap results in a severalfold increase in the SAEB amplitude (the number of electrons in the beam). At a generator voltage of 25 kV, nitrogen pressure of 90 Torr, and pulse repetition frequency of 3.5 kHz, a runaway electron beam was detected behind the anode foil.

Baksht, E. Kh.; Burachenko, A. G.; Erofeev, M. V.; Tarasenko, V. F.

2014-05-01

370

Beam patterns and geometries of X-ray pulsars obtained from their pulse profiles  

NASA Astrophysics Data System (ADS)

We present energy-and luminosity-dependent beam patterns of the accreting neutron star in the transient Be/X-ray binary systems A 0535+26, EXO 2030+375, and 4U 0115+63 and their ge-ometries. We have analyzed the pulse profiles of these X-ray pulsars observed during outbursts, which show strong dependence both on energy and on the luminosity and are asymmetric in shape. The pulse profile decomposition method, which enables us to find two symmetric pulse profiles for the two magnetic poles of the neutron star, has revealed that the magnetic field of the neutron stars is slightly distorted in all three systems. During the revolution of the neutron star, both poles disappear behind the horizon for a short period of time. A significant fraction of the emission has its origin in a fan beam that is also observed while the emitting accretion column is behind the neutron star due to gravitational line bending. The beam patterns are interpreted in terms of a geometrical model of a hollow column that includes the formation of a halo around the accretion column and that takes relativistic light deflection into account.

Sasaki, Manami; Santangelo, Andrea; Caballero, Isabel; Ferrigno, Carlo; Klochkov, Dmitry; Kraus, Ute

371

X-ray Interferometry with Transmissive Beam Combiners for Ultra-High Angular Resolution Astronomy  

NASA Technical Reports Server (NTRS)

Abstract Interferometry provides one of the possible routes to ultra-high angular resolution for X-ray and gamma-ray astronomy. Sub-micro-arc-second angular resolution, necessary to achieve objectives such as imaging the regions around the event horizon of a super-massive black hole at the center of an active galaxy, can be achieved if beams from parts of the incoming wavefront separated by 100s of meters can be stably and accurately brought together at small angles. One way of achieving this is by using grazing incidence mirrors. We here investigate an alternative approach in which the beams are recombined by optical elements working in transmission. It is shown that the use of diffractive elements is a particularly attractive option. We report experimental results from a simple 2-beam interferometer using a low-cost commercially available profiled film as the diffractive elements. A rotationally symmetric filled (or mostly filled) aperture variant of such an interferometer, equivalent to an X-ray axicon, is shown to offer a much wider bandpass than either a Phase Fresnel Lens (PFL) or a PFL with a refractive lens in an achromatic pair. Simulations of an example system are presented.

Skinner, G. K.; Krismanic, John F.

2009-01-01

372

Investigation on the properties of a laminar grating as a soft x-ray beam splitter  

SciTech Connect

Laminar-type gratings as soft x-ray beam splitters for interferometry are presented. Gold-coated grating beam splitters with 1000 lines/mm are designed for grazing incidence operation at 13.9nm. They are routinely fabricated using electron beam lithography and ion etching techniques. The laminar grating is measured to have almost equal absolute efficiencies of about 20% in the zeroth and -1st orders, which enables a fringe visibility up to 0.99 in the interferometer. The discrepancy of the grating profiles between the optimized theoretical and the experimental results is analyzed according to the comparison of the optimized simulation results and the measurement realization of the grating efficiencies. By a precise control of the grating profile, the grating efficiency in the -1st order and the fringe visibility could be improved to 25% and 1, respectively.

Liu Ying; Fuchs, Hans-Joerg; Liu Zhengkun; Chen Huoyao; He Shengnan; Fu Shaojun; Kley, Ernst-Bernhard; Tuennermann, Andreas

2010-08-10

373

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

PubMed Central

Purpose: The purpose of this study was to develop and validate a mathematical model to describe narrow-beam attenuation of kilovoltage x-ray beams for the intended applications of half-value layer (HVL) and quarter-value layer (QVL) estimations, patient organ shielding, and computer modeling. Methods: An empirical model, which uses the Lambert W function and represents a generalized Lambert-Beer law, was developed. To validate this model, transmission of diagnostic energy x-ray beams was measured over a wide range of attenuator thicknesses [0.49–33.03 mm Al on a computed tomography (CT) scanner, 0.09–1.93 mm Al on two mammography systems, and 0.1–0.45 mm Cu and 0.49–14.87 mm Al using general radiography]. Exposure measurements were acquired under narrow-beam geometry using standard methods, including the appropriate ionization chamber, for each radiographic system. Nonlinear regression was used to find the best-fit curve of the proposed Lambert W model to each measured transmission versus attenuator thickness data set. In addition to validating the Lambert W model, we also assessed the performance of two-point Lambert W interpolation compared to traditional methods for estimating the HVL and QVL [i.e., semilogarithmic (exponential) and linear interpolation]. Results: The Lambert W model was validated for modeling attenuation versus attenuator thickness with respect to the data collected in this study (R2?>?0.99). Furthermore, Lambert W interpolation was more accurate and less sensitive to the choice of interpolation points used to estimate the HVL and?or QVL than the traditional methods of semilogarithmic and linear interpolation. Conclusions: The proposed Lambert W model accurately describes attenuation of both monoenergetic radiation and (kilovoltage) polyenergetic beams (under narrow-beam geometry).

Mathieu, Kelsey B.; Kappadath, S. Cheenu; White, R. Allen; Atkinson, E. Neely; Cody, Dianna D.

2011-01-01

374

Subacute Neuropathological Effects of Microplanar Beams of X-Rays from a Synchrotron Wiggler  

NASA Astrophysics Data System (ADS)

Microplanar beam radiation therapy has been proposed to treat brain tumors by using a series of rapid exposures to an array of parallel x-ray beams, each beam having uniform microscopic thickness and macroscopic breadth (i.e., microplanar). Thirty-six rats were exposed head-on either to an upright 4-mm-high, 20- or 37-? m-wide beam or to a horizontal 7-mm-wide, 42-? m-high beam of mostly 32- to 126-keV, minimally divergent x-rays from the X17 wiggler at the National Synchrotron Light Source at Brookhaven National Laboratory. Parallel slices of the head, separated at either 75 or 200 ? m on center, were exposed sequentially at 310-650 grays (Gy) per second until each skin-entrance absorbed dose reached 312, 625, 1250, 2500, 5000, or 10,000 Gy. The rats were euthanized 2 weeks or 1 month later. Two rats with 10,000-Gy-entrance slices developed brain tissue necrosis. All the other 10,000- and 5000-Gy-entrance slices and some of the 2500- and 1250-Gy-entrance slices showed loss of neuronal and astrocytic nuclei and their perikarya. No other kind of brain damage was evident histologically in any rat with entrance absorbed doses <=5000 Gy. Brain tissues in and between all the 312- and 625-Gy-entrance slices appeared normal. This unusual resistance to necrosis is central to the rationale of microplanar beam radiation therapy for brain tumors.

Slatkin, D. N.; Spanne, P.; Dilmanian, F. A.; Gebbers, J.-O.; Laissue, J. A.

1995-09-01

375

Flash X-Ray (FXR) Accelerator Optimization Beam-induced Voltage Simulation and TDR Measurements  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) is evaluating design alternatives to improve the voltage regulation in our Flash X-Ray (FXR) accelerator cell and pulse-power system. The goal is to create a more mono-energetic electron beam. When an electron beam crosses the energized gap of an accelerator cell, the electron energy is increased. However, the beam with the associated electromagnetic wave also looses a small amount of energy because of the increased impedance seen across the gap. The beam-induced voltage at the gap is time varying. This creates beam energy variations that we need to understand and control. A high-fidelity computer simulation of the beam and cell interaction has been completed to quantify the time varying induced voltage at the gap. The cell and pulse-power system was characterized using a Time-domain Reflectometry (TDR) measurement technique with a coaxial air-line to drive the cell gap. The beam-induced cell voltage is computed by convoluting the cell impedance with measured beam current. The voltage was checked against other measurements to validate the accuracy.

Ong, M M; Vogtlin, G E

2005-05-12

376

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

PubMed Central

Monte Carlo simulations of x-ray beams typically take parameters of the electron beam in the accelerating waveguide to be free parameters. In this paper, a methodology is proposed and implemented to determine the energy, spectral width, and beam divergence of the electron source. All treatment head components were removed from the beam path, leaving only the exit window. With the x-ray target and flattener out of the beam, uncertainties in physical characteristics and relative position of the target and flattening filter, and in spot size, did not contribute to uncertainty in the energy. Beam current was lowered to reduce recombination effects. The measured dose distributions were compared with Monte Carlo simulation of the electron beam through the treatment head to extract the electron source characteristics. For the nominal 6 and 18 MV x-ray beams, the energies were 6.51±0.15 and 13.9±0.2 MeV, respectively, with the uncertainties resulting from uncertainties in the detector position in the measurement and in the stopping power in the simulations. Gaussian spectral distributions were used, with full widths at half maximum ranging from 20±4% at 6 MV to 13±4% at 18 MV required to match the fall-off portion of the percent-depth ionization curve. Profiles at the depth of maximum dose from simulations that used the manufacturer-specified exit window geometry and no beam divergence were 2–3 cm narrower than measured profiles. Two simulation configurations yielding the measured profile width were the manufacturer-specified exit window thickness with electron source divergences of 3.3° at 6 MV and 1.8° at 18 MV and an exit window 40% thicker than the manufacturer’s specification with no beam divergence. With the x-ray target in place (and no flattener), comparison of measured to simulated profiles sets upper limits on the electron source divergences of 0.2° at 6 MV and 0.1° at 18 MV. A method of determining source characteristics without mechanical modification of the treatment head, and therefore feasible in clinics, is presented. The energies and spectral widths determined using this method agree with those determined with only the exit window in the beam path.

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

2009-01-01

377

X-ray beam lines and beam line components for the SLAC Linac Coherent Light Source (LCLS)  

SciTech Connect

The LCLS is a novel high-brightness x-ray source designed to operate in the 300--400 eV range. In contrast to conventional synchrotron radiation sources, its output pulses will be characterized by unprecedented levels of brevity and peak power. In this paper we present recently-developed beam line layouts and design features intended to optimize the delivery of the LCLS photons to various experimental stations.

Tatchyn, R.; Pianetta, P.

1993-04-01

378

Intensity and spectral variability of strong galactic X-ray sources observed by ANS  

NASA Technical Reports Server (NTRS)

Hard X-ray observations by the ANS are used to analyze the energy spectrum and intensity fluctuations on time scales of seconds to days for 20 luminous galactic sources, of which 11 are galactic-bulge (GX) sources having no obvious identification with source categories. It is found that: (1) most GX sources are best fitted in the energy range from about 1 to 20 keV by exponential spectra with a source temperature (kT) of approximately 5 keV; (2) iron line emission around 6.7 keV is always detected as a persistent spectral feature of at least six and possibly seven of the sources studied; (3) most of the iron-line sources exhibit a direct correlation between kT and intensity (I) in the band from 1.4 to 7.2 keV; (4) no burst source counterparts or candidates show a direct correlation between kT and I, at least two show an inverse correlation, and no iron line emission is detected at a 3-sigma level from burster counterparts during burst-active states. A classification scheme for GX sources is proposed, and several observational tests for this scheme and for possible source models are described.

Parsignault, D. R.; Grindlay, J. E.

1978-01-01

379

Target diagnostics for intense lithium ion hohlraum experiments on Particle Beam Fusion Accelerator II  

Microsoft Academic Search

A review of the diagnostics used at Sandia National Laboratories to measure the parameters of intense lithium ion-beam hohlraum target experiments on Particle Beam Fusion Accelerator II will be presented. This diagnostic package contains an extensive suite of x-ray spectral and imaging diagnostics that enable measurements of target temperature and x-ray output. The x-ray diagnostics include time-integrated and time-resolved pinhole

R. J. Leeper; J. E. Bailey; A. L. Carlson; G. A. Chandler; M. S. Derzon; R. J. Dukart; D. E. Hebron; J. A. Hunter; L. P. Mix; A. R. Moats; T. J. Nash; W. R. Olson; P. D. Rockett; C. L. Ruiz; J. A. Torres; R. W. Olsen; T. L. Barber; P. W. Lake; F. A. Schmidlapp

1995-01-01

380

Integral window/photon beam position monitor and beam flux detectors for x-ray beams  

DOEpatents

A monitor/detector assembly in a synchrotron for either monitoring the position of a photon beam or detecting beam flux may additionally function as a vacuum barrier between the front end and downstream segment of the beamline in the synchrotron. A base flange of the monitor/detector assembly is formed of oxygen free copper with a central opening covered by a window foil that is fused thereon. The window foil is made of man-made materials, such as chemical vapor deposition diamond or cubic boron nitrate and in certain configurations includes a central opening through which the beams are transmitted. Sensors of low atomic number materials, such as aluminum or beryllium, are laid on the window foil. The configuration of the sensors on the window foil may be varied depending on the function to be performed. A contact plate of insulating material, such as aluminum oxide, is secured to the base flange and is thereby clamped against the sensor on the window foil. The sensor is coupled to external electronic signal processing devices via a gold or silver lead printed onto the contact plate and a copper post screw or alternatively via a copper screw and a copper spring that can be inserted through the contact plate and coupled to the sensors. In an alternate embodiment of the monitor/detector assembly, the sensors are sandwiched between the window foil of chemical vapor deposition diamond or cubic boron nitrate and a front foil made of similar material.

Shu, Deming (Darien, IL); Kuzay, Tuncer M. (Naperville, IL)

1995-01-01

381

Monte Carlo simulation of an x-ray volume imaging cone beam CT unit  

SciTech Connect

In this work the authors characterized the radiation field produced by a kilovolt cone beam computed tomography (CBCT) unit integrated in the Elekta Synergy linear accelerator. The x-ray volume imaging (XVI) radiation unit was modeled in detail using the BEAMNRC Monte Carlo (MC) code system. The simulations of eight collimator cassettes and the neutral filter F0 were successfully carried out. MC calculations from the EGSNRC code DOSXYZNRC were benchmarked against measurements in water. A large set of depth dose and lateral profiles was acquired with the ionization chamber in water, with the x-ray tube in a stationary position, and with the beam energy set to 120 kV. Measurements for all the available collimator cassettes were compared with calculations, showing very good agreement (<2% in most cases). Furthermore, half value layer measurements were carried out and used to validate the MC model of the XVI unit. In this case dose calculations were performed with the EGSNRC code cavity and these showed excellent agreement. In this manuscript the authors also report on the optimization work of the relevant parameters that influenced the development of the MC model. The dosimetric part of this work was very useful in characterizing the XVI radiation output for the energy of interest. The detailed simulation part of the work is the first step toward an accurate MC based assessment of the dose delivered to patients during routine CBCT scans for image and dose guided radiotherapy.

Spezi, Emiliano; Downes, Patrick; Radu, Emil; Jarvis, Richard [Department of Medical Physics, Velindre Cancer Centre, Cardiff CF14 2TL (United Kingdom); School of Computer Science, Cardiff University, Cardiff CF24 3AA (United Kingdom); Department of Medical Physics, Velindre Cancer Centre, Cardiff CF14 2TL (United Kingdom)

2009-01-15

382

X-ray laser beam propagation in double-foil targets  

SciTech Connect

Refraction effects on the gain of an x-ray laser propagating in a convex (lateral) plasma density profile have been studied previously. Here the corresponding case of concave density profile is studied theoretically. Experimentally, the convex profile is obtained by irradiating a single (exploding) foil target; the concave case can be realized by various two-beam irradiation configurations. Such geometries have been studied experimentally at the Laboratory for Laser Energetics (LLE) ({ital SPIE} {ital Proceedings} (SPIE, Bellingham, WA, 1987), Vol. 831, Paper 40, p. 283; Paper 42, p. 305). The concave profile has a waveguiding effect on the propagation of the x-ray laser and can reduce the deleterious effects of refraction. The output power, its dependence on the length of the amplifying medium, and its angular distribution are studied and compared with the convex profile case. An amplifier mode (in which a collimated beam is incident on an amplifying medium) is compared with an amplified spontaneous emission mode (where spontaneous emission sources exist throughout the amplifying medium).

Boswell, B.; Shvarts, D.; Boehly, T.; Yaakobi, B. (Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (US))

1990-02-01

383

Development and application of glancing incident X-ray fluorescence spectrometry using parallel polycapillary X-ray lens  

Microsoft Academic Search

A new glancing incident X-ray fluorescence (GIXRF) spectrometer using parallel polycapillary X-ray lens has been developed. Integrated with a Zr filter and slits, a highly collimated and monochromatic X-ray beam has been achieved. This method eliminated the monochromator used in the conventional GIXRF method. Moreover the parallel X-ray lens increased the acceptance solid angle and hence increases intensities of the

Jun Yang; Dandan Zhao; Qing Xu; Xunliang Ding

2009-01-01

384

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications  

Microsoft Academic Search

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely

Dip Narayan Mahato

2009-01-01

385

Study of the X-ray energy utilization efficiency of the X-ray digital imaging systems in industrial applications  

Microsoft Academic Search

The purpose of the present paper is to study the X-ray energy utilization efficiency that is inherent in the improved design of actual X-ray digital imaging systems in industrial applications. Both the X-ray energy utilization efficiency and the light intensity of the X-ray beam are lowered distinctly while the distance of the focal length is increased for high spatial resolution

Li Ruihong; Han Yueping

2010-01-01

386

X-ray radiation from nonlinear Thomson scattering of an intense femtosecond laser on relativistic electrons in a helium plasma.  

PubMed

We have generated x-ray radiation from the nonlinear Thomson scattering of a 30 fs/1.5 J laser beam on plasma electrons. A collimated x-ray radiation with a broad continuous spectrum peaked at 0.15 keV with a significant tail up to 2 keV has been observed. These characteristics are found to depend strongly on the laser strength parameter a(0). This radiative process is dominant for a(0) greater than unity at which point the relativistic scattering of the laser light originates from MeV energy electrons inside the plasma. PMID:14611585

Ta Phuoc, K; Rousse, A; Pittman, M; Rousseau, J P; Malka, V; Fritzler, S; Umstadter, D; Hulin, D

2003-11-01

387

Comparison between beam-stop and beam-hole array scatter correction techniques for industrial X-ray cone-beam CT  

Microsoft Academic Search

In industrial X-ray cone-beam computed tomography, the inspection of large-scale samples is important because of increasing demands on their quality and long-term mechanical resilience. Large-scale samples, for example made of aluminum or iron, are strongly scattering X-rays. Scattered radiation leads to artifacts such as cupping, streaks, and a reduction in contrast in the reconstructed CT-volume. We propose a scatter correction

K. Schörner; M. Goldammer; J. Stephan

2011-01-01

388

Characterization of (111) Gaas and (111) InP substrates and homoepitaxial layers by divergent x-ray beam diffraction  

Microsoft Academic Search

The back-reflection diffraction of a divergent x-ray beam has been studied for the characterization of (111) GaAs and (111) InP substrates and homoepitaxial layers with different states of surface perfection. Diffraction conditions for generating back-reflection pseudo-Kossel patterns from (111) GaAs and (111) InP are presented. Mechanical polishing was observed to produce x-ray diffraction line broadening. Uneven line broadening was found

Alice L. Lin; Lee F. Donaghey

1977-01-01

389

Fresnel zone plate telescopes for X-ray imaging I: experiments with a quasi-parallel beam  

Microsoft Academic Search

Combination of Fresnel Zone Plates (FZP) can make an excellent telescope for imaging in X-rays. We present here the results\\u000a of our experiments with several pairs of tungsten made Fresnel Zone plates in presence of an X-ray source kept at a distance\\u000a of about 45 ft. The quasi-parallel beam allowed us to study sources placed on the axis as well as

Sandip K. Chakrabarti; S. Palit; D. Debnath; A. Nandi; V. Yadav; Ritabrata Sarkar

2009-01-01

390

Beam Damage of Poly(Vinyl Chloride) [PVC] Film as Observed by X-ray Photoelectron Spectroscopy  

SciTech Connect

XPS spectra of a spin-coated film poly(vinyl chloride) (PVC) were collected over a period of 243 minutes at 303 K to determine specimen damage during long exposures to monochromatic Al Ka x-rays. For this PVC film we measured the loss of chlorine as a function of time by rastering a focused 104.6 w 100 um diameter x-ray beam over a 1.4 mm x 0.2 mm area on the sample.

Engelhard, Mark H.; Krishna, Abhilash; Kulkarni, Pranita B.; Lee, Chi-Ying M.; Baer, Donald R.

2003-03-08

391

Ptychographical imaging of the phase vortices in the x-ray beam formed by nanofocusing lenses  

NASA Astrophysics Data System (ADS)

We present the ptychographical reconstruction of the x-ray beam formed by nanofocusing lenses (NFLs) containing a number of phase singularities (vortices) in the vicinity of the focal plane. As a test object Siemens star pattern was used with the finest features of 50 nm for ptychographical measurements. The extended ptychographical iterative engine (ePIE) algorithm was applied to retrieve both complex illumination and object functions from the set of diffraction patterns. The reconstruction revealed the focus size of 91.4±1.1 nm in horizontal and 70±0.3 nm in vertical direction at full width at half maximum (FWHM). The complex probe function was propagated along the optical axis of the beam revealing the evolution of the phase singularities.

Dzhigaev, D.; Lorenz, U.; Kurta, R. P.; Seiboth, F.; Stankevic, T.; Mickevicius, S.; Singer, A.; Shabalin, A.; Yefanov, O. M.; Strikhanov, M. N.; Falkenberg, G.; Schroer, C. G.; Feidenhans'l, R.; Vartanyants, I. A.

2014-04-01

392

Compact soft x-ray spectrometer for plasma diagnostics at the Heidelberg Electron Beam Ion Trap  

SciTech Connect

A compact flat-field soft x-ray grazing-incidence grating spectrometer equipped with a cryogenically cooled back-illuminated charge-coupled device camera was built and implemented at the Heidelberg Electron Beam Ion Trap. The instrument spans the spectral region from 1 to 37 nm using two different gratings. In slitless operation mode, it directly images a radiation source, in this case ions confined in an electron beam ion trap, with high efficiency and reaching hereby a resolving power of {lambda}/{delta}{lambda} congruent with 130 at 2 nm and of {lambda}/{delta}{lambda} congruent with 600 at 28 nm. Capable of automatized operation, its low noise and excellent stability make it an ideal instrument not only for spectroscopic diagnostics requiring wide spectral coverage but also for precision wavelength measurements.

Lapierre, A.; Crespo Lopez-Urrutia, J. R.; Baumann, T. M.; Epp, S. W.; Gonchar, A.; Gonzalez Martinez, A. J.; Liang, G.; Rohr, A.; Soria Orts, R.; Simon, M. C.; Tawara, H.; Versteegen, R.; Ullrich, J. [Max-Planck Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

2007-12-15

393

Matching X-ray beam and detector properties to protein crystals of different perfection  

PubMed Central

An analysis is given of the effect of different beam and detector parameters on the sharpness of recorded diffraction features for macromolecular crystals of different quality. The crystal quality parameters include crystal strain, crystal or mosaic block size and mosaic block misorientation. Calculations are given for instrument parameters such as angular resolution of the detector, beam divergence and wavelength bandpass to be matched to the intrinsic diffraction properties from these crystals with the aim of obtaining the best possible data out of each crystal. Examples are given using typical crystal imperfections obtained from the literature for both room-temperature and cryo-cooled crystals. Possible implications for the choice of X-ray source, beamline design, detector specifications, instrument set-up and data processing are discussed, together with the limitations of the approach.

Nave, Colin

2014-01-01

394

Diffraction with a coherent X-ray beam: dynamics and imaging  

PubMed Central

Methods for carrying out coherent X-ray scattering experiments are reviewed. The brilliance of the available synchrotron sources, the characteristics of the existing optics, the various ways of obtaining a beam of controlled coherence properties and the detectors used are summarized. Applications in the study of the dynamics of speckle patterns are described. In the case of soft condensed matter, the movement of inclusions like fillers in polymers or colloidal particles can be observed and these can reflect polymer or liquid-crystal fluctuations. In hard condensed-matter problems, like phase transitions, charge-density waves or phasons in quasicrystals, the study of speckle fluctuations provides new time-resolved methods. In the domain of lensless imaging, the coherent beam gives the modulus of the sample Fourier transform. If oversampling conditions are fulfilled, the phase can be obtained and the image in the direct space can be reconstructed. The forthcoming improvements of all these techniques are discussed.

Livet, Frederic

2007-01-01

395

Dosimetric application of a special pencil ionization chamber in radiotherapy X-ray beams  

NASA Astrophysics Data System (ADS)

The aim of this work was to study the performance of a pencil ionization chamber with a sensitive volume of only 1.06 cm3 and a length of 3.0 cm, developed at the Calibration Laboratory of the IPEN, in very low-energy radiotherapy X-ray beams. These beams are still used for certain skin cancer treatments due to their rapid attenuation in tissue. The dosimeter performance was evaluated in some tests proposed by the IEC 60731 standard: short- and long-term stability and linearity of response. For a complete analysis of the dosimeter response, the EGSnrc Monte Carlo simulation was utilized to investigate the influence of its different parts on the ionization chamber response. All results of the tests were in accordance with the recommended limits, and this work shows that it is possible to extend the application of this pencil-type ionization chamber developed at the LCI.

Neves, Lucio P.; Perini, Ana P.; Fernández-Varea, José M.; Cassola, Vagner F.; Kramer, Richard; Khoury, Helen J.; Caldas, Linda V. E.

2014-02-01

396

Chemical Environment Effects on K[beta]/K[alpha] Intensity Ratio: An X-Ray Fluorescence Experiment on Periodic Trends  

ERIC Educational Resources Information Center

X-ray fluorescence (XRF) data from an energy-dispersive XRF instrument were used to investigate the chlorine K[alpha] and K[beta] peaks in several group 1 salts. The ratio of the peak intensity is sensitive to the local chemical environment of the chlorine atoms studied in this experiment and it shows a periodic trend for these salts. (Contains 1…

Durham, Chaney R.; Chase, Jeffery M.; Nivens, Delana A.; Baird, William H.; Padgett, Clifford W.

2011-01-01

397

Multiple ionization of atom clusters by intense soft X-rays from a free-electron laser  

Microsoft Academic Search

Intense radiation from lasers has opened up many new areas of research in physics and chemistry, and has revolutionized optical technology. So far, most work in the field of nonlinear processes has been restricted to infrared, visible and ultraviolet light, although progress in the development of X-ray lasers has been made recently. With the advent of a free-electron laser in

H. Wabnitz; L. Bittner; A. R. B. de Castro; R. Döhrmann; P. Gürtler; T. Laarmann; W. Laasch; J. Schulz; A. Swiderski; K. von Haeften; T. Möller; B. Faatz; A. Fateev; J. Feldhaus; C. Gerth; U. Hahn; E. Schneidmiller; K. Sytchev; K. Tiedtke; R. Treusch; M. Yurkov

2002-01-01

398

Fluorescence x-ray absorption fine structure measurements using a synchrotron radiation x-ray microprobe  

Microsoft Academic Search

X-ray absorption fine structure (XAFS) measurements in regions less than 20 ?m in diameter were realized using an x-ray microprobe employing the fluorescence detection method. To realize an energy tunable intense small x-ray beam, an ellipsoidal mirror was used as the synchrotron radiation focusing element combined with a double-crystal monochromator. Distortion of a XAFS spectrum due to the self-absorption effect

Shinjiro Hayakawa; Yohichi Gohshi; Atsuo Iida; Sadao Aoki; Kohei Sato

1991-01-01

399

Evaluation of x-ray scatter properties in a dedicated cone-beam breast CT scanner.  

PubMed

The magnitude of scatter contamination on a first-generation prototype breast computed tomography (CT) scanner was evaluated using the scatter-to-primary ratio (SPR) metric. The SPR was measured and characterized over a wide range of parameters relevant to breast CT imaging, including x-ray beam energy, breast diameter, breast composition, isocenter-to-detector distance, collimated slot thickness, and grid ratio. The results demonstrated that in the absence of scatter reduction techniques, the SPR levels for the average breast (e.g., 14 cm diameter 50/50 composition cylindrical phantom) are quite high (approximately 0.5 at the center of the phantom for 80 kVp in true cone-beam CT geometry), and increases as the diameter of the phantom is increased (to approximately 1.0 at the center of a 18 cm diameter 50/50 phantom). The x-ray beam energy and the phantom compositions had only minimal impact on the measured SPR. When an ideal bowtie filter was used, the SPRs at the central axis of the 14 and 18 cm cylindrical phantoms were reduced while the SPRs at the edge of the phantoms were increased. Lastly, collimation in the vertical direction had a significant impact on the SPRs at the central axis of the phantoms. These high SPR levels might lead to cupping artifacts and increased noise in the reconstructed CT images, and this suggests that efficient scatter rejection and/or correction techniques may be required to improve the quality and accuracy of cone beam CT images. PMID:16266111

Kwan, Alexander L C; Boone, John M; Shah, Nikula

2005-09-01

400

Multiphoton Ionization as a clock to Reveal Molecular Dynamics with Intense Short X-ray Free Electron Laser Pulses  

NASA Astrophysics Data System (ADS)

We investigate molecular dynamics of multiple ionization in N2 through multiple core-level photoabsorption and subsequent Auger decay processes induced by intense, short x-ray free electron laser pulses. The timing dynamics of the photoabsorption and dissociation processes is mapped onto the kinetic energy of the fragments. Measurements of the latter allow us to map out the average internuclear separation for every molecular photoionization sequence step and obtain the average time interval between the photoabsorption events. Using multiphoton ionization as a tool of the multiple-pulse pump-probe scheme, we demonstrate the modification of the ionization dynamics as we vary the x-ray laser pulse duration.

Fang, L.; Osipov, T.; Murphy, B.; Tarantelli, F.; Kukk, E.; Cryan, J. P.; Glownia, M.; Bucksbaum, P. H.; Coffee, R. N.; Chen, M.; Buth, C.; Berrah, N.

2012-12-01

401

An alignment method for the ATLAS end-cap TRT detector using a narrow monochromatic X-ray beam  

NASA Astrophysics Data System (ADS)

The end-cap Transition Radiation Tracker (TRT), consisting of 36 modules (wheels), is being constructed as a part of the ATLAS Inner Detector at the CERN LHC. This paper describes a method for determining the wire positions inside the straw proportional tubes (SPT), which are the basic building blocks of the ATLAS TRT, with an accuracy of better than 10 ?m. The procedure involves moving a narrow monochromatic X-ray beam across the straw and measuring the counting rate as a function of the position of the X-ray beam in the straw. To achieve this goal, a Beam Directing Device (BDD), providing the possibility to direct the X-ray beam in a chosen direction within some solid angle and supplying an accurate angular measurement system, has been constructed. The results of the wire position measurements performed using this BDD on a full-scale mechanical prototype end-cap wheel of the TRT are presented in this paper.

Akesson, T.; Danielsson, H.; Dixon, N.; Dolgoshein, B.; Eerola, P.; Farthouat, P.; Fedin, O.; Froidevaux, D.; Gavrilenko, I.; Hajduk, Z.; Hauviller, C.; Ivanov, V.; Ivochkin, V.; Jelamkov, A.; Konovalov, S.; Lichard, P.; Lundberg, B.; Muraviev, S.; Nadtochy, A.; Nevski, P.; Peshekhonov, V.; Platonov, Y.; Price, M.; Romaniouk, A.; Schegelsky, V.; Shmeleva, A.; Smirnov, A.; Smirnov, S.; Sosnovtsev, V.

2001-05-01

402

Hot electron and x-ray production from intense laser irradiation of wavelength-scale polystyrene spheres  

SciTech Connect

Hot electron and x-ray production from solid targets coated with polystyrene-spheres which are irradiated with high-contrast, 100 fs, 400 nm light pulses at intensity up to 2x10{sup 17} W/cm{sup 2} have been studied. The peak hard x-ray signal from uncoated fused silica targets is an order of magnitude smaller than the signal from targets coated with submicron sized spheres. The temperature of the x-rays in the case of sphere-coated targets is twice as hot as that of uncoated glass. A sphere-size scan of the x-ray yield and observation of a peak in both the x-ray production and temperature at a sphere diameter of 0.26 {mu}m, indicate that these results are consistent with Mie enhancements of the laser field at the sphere surface and multipass stochastic heating of the hot electrons in the oscillating laser field. These results also match well with particle-in-cell simulations of the interaction.

Sumeruk, H. A.; Kneip, S.; Symes, D. R.; Churina, I. V.; Belolipetski, A. V.; Dyer, G.; Landry, J.; Bansal, G.; Bernstein, A.; Donnelly, T. D.; Karmakar, A.; Pukhov, A.; Ditmire, T. [Texas Center for High Intensity Laser Science, Department of Physics, University of Texas, Austin, Texas 78712 (United States); Department of Physics, Harvey Mudd College, Claremont, California 91711 (United States); Institut fuer Theoretische Physik I, Heinrich-Heine-University of Dusseldorf, 40225 Dusseldorf (Germany); Texas Center for High Intensity Laser Science, Department of Physics, University of Texas, Austin, Texas 78712 (United States)

2007-06-15

403

Analysis of a Novel Diffractive Scanning Wire Beam Position Monitor (BPM) for Discriminative Profiling of Electron Vs. X Ray Beams  

SciTech Connect

Recent numerical studies of Free Electron Lasers (FELs) operating in the Self Amplified Spontaneous Emission (SASE) regime indicate a large sensitivity of the gain to the degree of transverse overlap (and associated phase coherence) between the electron and photon beams traveling down the insertion device. Simulations of actual systems imply that accurate detection and correction for this relative loss of overlap, rather than correction for the absolute departure of the electron beam from a fixed axis, is the preferred function of an FEL amplifier's Beam Position Monitor (BPM) and corrector systems. In this note we propose a novel diffractive BPM with the capability of simultaneously detecting and resolving the absolute (and relative) transverse positions and profiles of electron and x-ray beams co-propagating through an undulator. We derive the equations governing the performance of the BPM and examine its predicted performance for the SLAC Linac Coherent Light Source (LCLS), viz., for profiling multi-GeV electron bunches co-propagating with one-to-several-hundred keV x-ray beams. Selected research and development (r&d) tasks for fabricating and testing the proposed BPM are discussed.

Tatchyn, Roman; /SLAC

2011-09-01

404

MPD intense beam pulser  

SciTech Connect

An MPD intense beam pulser for generating high voltage, intense charged particle beams utilizing an electromechanical energy source and inductive energy storage in combination with a plasma opening switch including a source of directed plasma flow, a diode for accelerating particles in the plasma flowing from the source, and a plasma flow truncation circuit. In operation, a controlled plasma flow is used to conduct current from the energy source in order to supply a desired amount of energy to the magnetic field in the volume surrounding the plasma flow. Truncation of the plasma flow between the electrodes forming the diode then provides a high voltage in a short pulse which generates a high energy charged particle beam. Thus, the magnetic energy store surrounding the diode plasma flow is coupled directly to the intense particle beam.

Turchi, P.J.; Virkovitsky, I.M.

1981-07-21

405

Intense ion beams  

NASA Astrophysics Data System (ADS)

A review is presented of the theory and experimental results on intense ion beam generation. The problems of generating intense ion beams in different reflex systems, the dynamics of charge flux accumulation, and the formation of the anode plasma are reviewed. Attention is given to magnetically insulated diode systems, their fundamental characteristics, and those of the ion beams that they generate. Intense ion beam shaping, neutralization, transport, and focusing are discussed. Applications are given, and include high-power neutron pulses and inertial controlled thermonuclear fusion. It is concluded that the stationary analytical modes that have been studied give good qualitative agreement with experimental data. Individual problems, such as the motion of the electrode plasma in the AC gap and the role of electrons scattered by the anode require further study.

Bystritskii, V. M.; Didenko, A. N.

1980-09-01

406

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

National Technical Information Service (NTIS)

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 ...

P. K. Carpenter

2005-01-01

407

Z pinches as intense x-ray sources for high-energy density physics applications  

Microsoft Academic Search

Fast Z-pinch implosions can efficiently convert the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator [R. B. Spielman {ital et al.}, in {ital Proceedings

M. Keith Matzen

1997-01-01

408

Z-pinches as intense x-ray sources for high energy density physics applications  

Microsoft Academic Search

Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example,

M. Keith Matzen

1996-01-01

409

High-energy x-ray source generation by short-pulse high-intensity lasers  

Microsoft Academic Search

We are studying the feasibility of utilizing Kalpha x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high aerial density planar samples driven by the NIF laser facility. The hard x-ray Kalpha sources are created by relativistic electron plasma interactions in the target material after a radiation by short

Hye-Sook Park; Jeffrey A. Koch; Otto L. Landen; Thomas W. Phillips; Tim J. Goldsack; E. Clark; Richard Eagleton; Ray D. Edwards

2004-01-01

410

Z pinches as intense x-ray sources for high-energy density physics applications  

Microsoft Academic Search

Fast Z-pinch implosions can efficiently convert the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator [R. B. Spielman &etal;, in Proceedings of the 2nd

M. Keith Matzen

1997-01-01

411

Z-pinches as intense x-ray sources for high energy density physics application  

Microsoft Academic Search

Fast z-pinch implosions can convert more than 10% of the stored electrical energy in a pulsed-power accelerator into x rays. These x rays are produced when an imploding cylindrical plasma, driven by the magnetic field pressure associated with very large axial currents, stagnates upon the cylindrical axis of symmetry. On the Saturn pulsed-power accelerator at Sandia National Laboratories, for example,

Matzen

1997-01-01

412

High Energy X-Ray Source Generation by Short Pulse High Intensity Lasers  

Microsoft Academic Search

We are studying the feasibility of utilizing K x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high areal density planar samples driven by the NIF laser facility. The hard x-ray K sources are created by relativistic electron plasma interactions in the target material after a radiation by short

H-S Park; J A Koch; O L Landen; T W Phillips; T Goldsack; E Clark; R Eagleton; R Edwards

2003-01-01

413

Wire-array z pinches as intense x-ray sources for inertial confinement fusion  

Microsoft Academic Search

Progress in pulsed power technologies has enabled the use of z pinches for inertia