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1

Thomson Backscattered X-rays from an Intense Laser Beam.  

National Technical Information Service (NTIS)

We have formulated and obtained analytical expressions for Thomson backscattered x-ray radiation for an electron beam incident on a linearly polarized electromagnetic undulator at a small angle. The analytical expressions are valid for fundamental and har...

C. M. Tang B. Hafizi S. K. Ride

1993-01-01

2

Lattice and beam parameters of compact intense x-ray sources based on Compton scattering  

NASA Astrophysics Data System (ADS)

The lattice of a laser-electron storage ring with a controlled momentum compaction factor dedicated to the generation of intense x rays under Compton scattering is described. In such a storage ring one can obtain large energy acceptance and keep the long-term stable motion of the electron beam with large energy spread. The intensity of x rays is stable due to the use of electron beam with steady-state parameters for Compton scattering. Parameters of the storage ring, electron beam, and x rays obtained by electron beam dynamics simulation involving both intrabeam and Compton scattering are presented.

Gladkikh, Peter

2005-05-01

3

Progress in rod pinch electron beam diodes as intense x-ray radiography sources  

Microsoft Academic Search

Rod-pinch electron beam diodes were reintroduced at BEAMS'98 as small-diameter intense x-ray sources after a twenty-year hiatus. Much progress has been made recently in both analytical and particle-in-cell numerical modeling of the diode behavior and in obtaining intense x-ray sources for pulsed radiography. Rod-pinch diodes utilize a thin annular cathode surrounding a small-diameter anode rod extending through and beyond the

G. Cooperstein; R. J. Commisso; D. D. Hinshelwood; D. Mosher; P. F. Ottinger; S. J. Stephanakis; J. W. Schumer; S. B. Swanekamp; B. V. Weber; F. C. Young; J. E. Maenchen; P. R. Menge; C. L. Olson; B. V. Oliver; D. V. Rose; D. R. Welch; R. Carlson; D. Oro; D. Fulton; E. Hunt; D. Droemer; W. J. DeHope

2000-01-01

4

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

NASA Astrophysics Data System (ADS)

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 ?m.

Revesz, Peter; Ruff, Jacob; Dale, Darren; Krawczyk, Thomas

2013-05-01

5

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

PubMed

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 ?m. PMID:23742534

Revesz, Peter; Ruff, Jacob; Dale, Darren; Krawczyk, Thomas

2013-05-01

6

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

7

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

8

Intense sources of monochromatic X-rays for XRF analysis from cyclotron beams  

Microsoft Academic Search

The possibility of using energetic proton beams to induce characteristic X-rays from pure elemental targets has been investigated. The K X-ray yields and the background radiation produced by 1-100 MeV protons striking a number of different targets have been calculated. Activation of the target caused by nuclear reactions has also been evaluated. The results show that yields as high as

L. Avaldi; S. Bassi; M. Milazzo; M. Silari

1990-01-01

9

Generating 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 to generate harmonic numbers of a few hundred in a microbunched beam through up-conversion of the frequency of an ultraviolet seed laser. Sending this beam through a short undulator results in an isolated sub-100 attoseconds pulse of x-ray radiation. Using a representative realistic set of parameters, we show that 1 nm x-ray pulse with peak power exceeding 100 MW and duration as short as 34 attoseconds (FWHM) can be generated from a 200 nm ultraviolet seed laser.

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

2009-03-04

10

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

11

Optimizing radiotherapy of orbital and paraorbital tumors: intensity-modulated X-ray beams vs. intensity-modulated proton beams  

Microsoft Academic Search

Purpose: This study presents a dosimetric optimization effort aiming to compare intensity-modulated (IM) X-rays and IM protons in 4 different orbital and paraorbital tumors. These are most challenging targets for standard radiotherapy due to their close relationship with the eyes and related structures.Methods and Materials: A primary orbital lymphoma, an optic nerve meningioma, a sphenoidal ridge meningioma protruding into the

Raymond Miralbell; Laura Cella; Damien Weber; Antony Lomax

2000-01-01

12

High-intensity electron beam for liquid-metal-jet anode hard x-ray generation  

NASA Astrophysics Data System (ADS)

We report on our progress towards the experimental realization of a liquid-metal-jet-anode x-ray source with high brightness. We have previously shown that this electron-impact source has potential for very high x-ray brightness by combining small-spot high-flux operation of the electron beam with high-speed operation of the regenerative liquid-metal-jet anode. In the present paper we review the system and describe theoretical calculations for improving the 50 kV, 600 W electron-beam focussing to ~30 ?m spot size. With such a system the power density on the liquid-metal-jet would be ~400 kW/mm2, i.e., more than an order of magnitude higher than the power density on a state-of-the-art rotating anode.

Tuohimaa, Tomi; Otendal, Mikael; Hertz, Hans M.

2005-08-01

13

X-ray pixel beam array systems and methods for electronically shaping radiation fields and modulation radiation field intensity patterns for radiotherapy  

US Patent & Trademark Office Database

X-ray pixel beam array systems and methods for electronically shaping radiation fields and modulating radiation field intensity patterns for radiotherapy are disclosed. One exemplary pre-clinical system may include addressable electron field emitters (102, 104) that are operable to emit a plurality of electron pixel beams (106, 108, 110). Each electron pixel beam may correspond to an x-ray target (124) and x-ray pixel beam collimation aperture (136, 138) to convert a portion of energy associated with the electron pixel beam to a corresponding x-ray pixel beam (140, 142). Further, the x-ray pixel beam array collimator (130) forms a one-to-one correspondence between individual electron pixel beam and its corresponding x-ray pixel beam. One exemplary clinical system may include a high-energy electron source (1203), an n-stage scanning system (1210), x-ray pixel beam targets (1212), and an x-ray pixel beam array collimator (1214). A controller (1206) may sequentially direct electron beam pulses to predetermined x-ray pixel targets and produce an electronically controlled radiation field direction, pattern; and intensity pattern.

2012-11-06

14

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.

15

Results of a search for paraphotons with intense X-ray beams at SPring-8  

NASA Astrophysics Data System (ADS)

A search for paraphotons, or hidden U(1) gauge bosons, is performed using an intense X-ray beamline at SPring-8. "Light Shining through a Wall" technique is used in this search. No excess of events above background is observed. A stringent constraint is obtained on the photon–paraphoton mixing angle, ?<8.06×10?5 (95% C.L.) for 0.04 eV

Inada, T.; Namba, T.; Asai, S.; Kobayashi, T.; Tanaka, Y.; Tamasaku, K.; Sawada, K.; Ishikawa, T.

2013-05-01

16

Generation of Intense X-Rays and Low-Emittance Electron Beams in a Laser-Electron Storage Ring  

NASA Astrophysics Data System (ADS)

Radiation damping and quantum excitation in an electron storage ring with a laser-electron interaction region are analyzed. Two interesting regimes and their perspectives to the generation of intense x-rays and low-emittance electron beams are investigated. In the first regime, a high-average-power laser beam inside a high-finesse resonator intersects with the electron beam every pass to produce very intense, hard x-rays. Although the transverse laser cooling effect is still weak compared with the normal synchrotron radiation damping, the increased energy spread induced by the Compton scattering stabilizes the electron beam against intrabeam scattering in a compact, low-energy ring. In the second regime, a high-peak-power laser pulse confined in the optical resonator is proposed to cool the electron beam transversely for the generation of low-emittance electron beams. We consider some basic optical system and storage ring requirements and discuss potential demonstration experiments at the existing accelerator facilities.

Huang, Zhirong

2000-12-01

17

Generation of intense x-rays and low-emittance electron beams in a laser-electron storage ring  

SciTech Connect

Radiation damping and quantum excitation in an electron storage ring with a laser-electron interaction region are analyzed. Two interesting regimes and their perspectives to the generation of intense x-rays and low-emittance electron beams are investigated. In the first regime, a high-average-power laser beam inside a high-finesse resonator intersects with the electron beam every pass to produce very intense, hard x-rays. Although the transverse laser cooling effect is still weak compared with the normal synchrotron radiation damping, the increased energy spread induced by the Compton scattering stabilizes the electron beam against intrabeam scattering in a compact, low-energy ring. In the second regime, a high-peak-power laser pulse confined in the optical resonator is proposed to cool the electron beam transversely for the generation of low-emittance electron beams. The authors consider some basic optical system and storage ring requirements and discuss potential demonstration experiments at the existing accelerator facilities.

Huang, Z.

2000-04-03

18

Apparatus for monitoring X-ray beam alignment  

Microsoft Academic Search

A self-contained, hand-held apparatus is provided for minitoring alignment of an X-ray beam in an instrument employing an X-ray source. The apparatus includes a transducer assembly containing a photoresistor for providing a range of electrical signals responsive to a range of X-ray beam intensities from the X-ray beam being aligned. A circuit, powered by a 7.5 VDC power supply and

Peter A

1991-01-01

19

Apparatus for monitoring x-ray beam alignment  

Microsoft Academic Search

A self-contained, hand-held apparatus is provided for monitoring alignment of an x-ray beam in an instrument employing an x-ray source. The apparatus includes a transducer assembly containing a photoresistor for providing a range of electrical signals responsive to a range of x-ray beam intensities from the x-ray beam being aligned. A circuit, powered by a 7.5 VDC power supply and

1989-01-01

20

Apparatus for monitoring X-ray beam alignment  

Microsoft Academic Search

A self-contained, hand-held apparatus is provided for monitoring alignment of an X-ray beam in an instrument employing an X-ray source. The apparatus includes a transducer assembly containing a photoresistor for providing a range of electrical signals responsive to a range of X-ray beam intensities from the X-ray beam being aligned. A circuit, powered by a 7.5 VDC power supply and

1991-01-01

21

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

22

X-ray intensity interferometer for undulator radiation  

SciTech Connect

Intensity interferometry is well established with visible light but has never been demonstrated with x-radiation. We propose to measure the transverse coherence of an x-ray beam, for the first time, using the method of Hanbury Brown and Twiss. The x-ray interferometer consists of an array of slits, a grazing incidence reflective beamsplitter, a pair of fast multichannel plate detectors and a broadband, low-noise correlator circuit. The NSLS X1 or X13 soft x-ray undulator will supply the partially coherent x-rays. We are developing this technique to characterize the coherence properties of x-ray beams from high brilliance insertion devices at third-generation synchrotron light facilities such as the Advanced Photon Source and the Advanced Light Source. 17 refs.

Gluskin, E.; McNulty, I.; Viccaro, P.J. (Argonne National Lab., IL (United States)); Howells, M.R. (Lawrence Berkeley Lab., CA (United States))

1991-01-01

23

X-ray intensity interferometer for undulator radiation  

SciTech Connect

Intensity interferometry is well established with visible light but has never been demonstrated with x-radiation. We propose to measure the transverse coherence of an x-ray beam, for the first time, using the method of Hanbury Brown and Twiss. The x-ray interferometer consists of an array of slits, a grazing incidence reflective beamsplitter, a pair of fast multichannel plate detectors and a broadband, low-noise correlator circuit. The NSLS X1 or X13 soft x-ray undulator will supply the partially coherent x-rays. We are developing this technique to characterize the coherence properties of x-ray beams from high brilliance insertion devices at third-generation synchrotron light facilities such as the Advanced Photon Source and the Advanced Light Source. 17 refs.

Gluskin, E.; McNulty, I.; Viccaro, P.J. [Argonne National Lab., IL (United States); Howells, M.R. [Lawrence Berkeley Lab., CA (United States)

1991-12-31

24

New techniques for the measurement of x-ray beam or x-ray optics quality  

NASA Astrophysics Data System (ADS)

Metrology of XUV beams and more specifically X-ray laser (XRL) beam is of crucial importance for development of applications. We have then developed several new optical systems enabling to measure the x-ray laser optical properties. By use of a Michelson interferometer working as a Fourier-Transform spectrometer, the line shapes of different x-ray lasers have been measured with an unprecedented accuracy (??/?~10-6). Achievement of the first XUV wavefront sensor has enable to measure the beam quality of laser-pumped as well as discharge pumped x-ray lasers. Capillary discharge XRL has demonstrated a very good wavefront allowing to achieve intensity as high 3*1014 Wcm-2 by focusing with a f = 5 cm mirror. The measured sensor accuracy is as good as ?/120 at 13 nm. Commercial developments are under way.

Zeitoun, Philippe; Balcou, Philippe; Bucourt, Samuel; Benredjem, Djamel; Delmotte, Franck; Dovillaire, Guillaume; Douillet, Denis; Dunn, James; Faivre, G.; Fajardo, Marta; Goldberg, Kenneth A.; Idir, Mourad; Hubert, Sebastien; Hunter, Jim; Jacquemot, Sylvie; Kazamias, Sophie; le Pape, Sebastien; Levecq, Xavier; Lewis, Ciaran L. S.; Marmoret, Remy; Mercere, Pascal; Morlens, A. S.; Naulleau, Patrick P.; Remond, Christian; Rocca, Jorge J.; Sebban, Stephane; Smith, Raymond F.; Ravet, Marie-Francoise; Troussel, Philippe; Valentin, Constance; Vanbostal, Laurent

2003-12-01

25

Development of high throughput multilayer x-ray beam conditioning optics for hard x-ray  

Microsoft Academic Search

Graphite monochromator and total reflection mirror (TR) systems have been widely used as x-ray beam conditioning optics for diffractometers and many other kinds of instruments. These optics serve as collimating tools, intensity enhancement tools, and band pass filters. A graphite monochromator is a Bragg reflector and delivers monochromatic beam. But the collimating and enhancement capability is poor. In some cases,

Licai Jiang

1998-01-01

26

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

27

Dependence of relative intensity of L1 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 × 106 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

28

Parametric X-ray radiation for calibration of X-ray space telescopes and generation of several X-ray beams  

NASA Astrophysics Data System (ADS)

The setup based on a moderate energy linear accelerator (linac) is proposed to provide users with a tunable, quasi-monochromatic, linearly polarized X-ray beam. The effect of parametric X-ray radiation (PXR) from relativistic electrons in a crystal is used in an X-ray source. The application of the setup for calibration of X-ray space telescopes and other equipment is considered. The setup allows calibration of angular, spectral, polarization parameters of telescopes with smooth tuning of X-ray energy from several keV to hundreds of keV. Estimates of X-ray flux intensities and spectral line widths on the telescope aperture at a distance of several hundred meters are presented. Besides, the PXR-based facility for simultaneous generation of several X-ray beams is proposed.

Shchagin, A. V.; Khizhnyak, N. A.; Fiorito, R. B.; Rule, D. W.; Artru, X.

2001-01-01

29

Clusters in intense x-ray pulses  

NASA Astrophysics Data System (ADS)

Free-electron lasers can deliver extremely intense, coherent x-ray flashes with femtosecond pulse length, opening the door for imaging single nanoscale objects in a single shot. All matter irradiated by these intense x-ray pulses, however, will be transformed into a highly-excited non-equilibrium plasma within femtoseconds. During the x-ray pulse complex electron dynamics and the onset of atomic disorder will be induced, leading to a time-varying sample. We have performed first experiments about x-ray laser pulse -- cluster interaction with a combined spectroscopy and imaging approach at both, the FLASH free electron laser in Hamburg (Germany) and the LCLS x-ray free-electron laser in Stanford (California). Atomic clusters are ideal for investigating the light - matter interaction because their size can be tuned from the molecular to the bulk regime, thus allowing to distinguish between intra and inter atomic processes. Imaging experiments with xenon clusters show power-density dependent changes in the scattering patterns. Modeling the scattering data indicates that the optical constants of the clusters change during the femtosecond pulse due to the transient creation of high charge states. The results show that ultra fast scattering is a promising approach to study transient states of matter on a femtosecond time scale. Coincident recording of time-of-flight spectra and scattering patterns allows the deconvolution of focal volume and particle size distribution effects. Single-shot single-particle experiments with keV x-rays reveal that for the highest power densities an highly excited and hot cluster plasma is formed for which recombination is suppressed. Time resolved infrared pump -- x-ray probe experiments have started. Here, the clusters are pumped into a nanoplasma state and their time evolution is probed with femtosecond x-ray scattering. The data show strong variations in the scattering patterns stemming from electronic reconfigurations in the cluster plasma. The results will be compared to theoretical predictions and discussed in light of current developments at free-electron laser sources.

Bostedt, Christoph

2012-06-01

30

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

31

Proton induced quasi-monochromatic x-ray beams for soft x-ray spectroscopy studies and selective x-ray fluorescence analysis.  

PubMed

We present the analytical features and performance of an x-ray spectroscopy end station of moderate energy resolution operating with proton-induced quasi-monochromatic x-ray beams. The apparatus was designed, installed and operated at the 5.5 MV Tandem VdG Accelerator Laboratory of the Institute of Nuclear Physics, N.C.S.R. "Demokritos," Athens. The setup includes a two-level ultrahigh vacuum chamber that hosts in the lower level up to six primary targets in a rotatable holder; there, the irradiation of pure element materials-used as primary targets-with few-MeV high current (~?A) proton beams produces intense quasi-monochromatic x-ray beams of selectable energy. In the chamber's upper level, a six-position rotatable sample holder hosts the targets considered for x-ray spectroscopy studies. The proton-induced x-ray beam, after proper collimation, is guided to the sample position whereas various filters can be also inserted along the beam's path to eliminate the backscattered protons or/and to absorb selectively components of the x-ray beam. The apparatus incorporates an ultrathin window Si(Li) spectrometer (FWHM 136 eV at 5.89 keV) coupled with low-noise electronics capable of efficiently detecting photons down to carbon K?. Exemplary soft x-ray spectroscopy studies and results of selective x-ray fluorescence analysis are presented. PMID:23277967

Sokaras, D; Zarkadas, Ch; Fliegauf, R; Beckhoff, B; Karydas, A G

2012-12-01

32

Proton induced quasi-monochromatic x-ray beams for soft x-ray spectroscopy studies and selective x-ray fluorescence analysis  

SciTech Connect

We present the analytical features and performance of an x-ray spectroscopy end station of moderate energy resolution operating with proton-induced quasi-monochromatic x-ray beams. The apparatus was designed, installed and operated at the 5.5 MV Tandem VdG Accelerator Laboratory of the Institute of Nuclear Physics, N.C.S.R. 'Demokritos,' Athens. The setup includes a two-level ultrahigh vacuum chamber that hosts in the lower level up to six primary targets in a rotatable holder; there, the irradiation of pure element materials-used as primary targets-with few-MeV high current ({approx}{mu}A) proton beams produces intense quasi-monochromatic x-ray beams of selectable energy. In the chamber's upper level, a six-position rotatable sample holder hosts the targets considered for x-ray spectroscopy studies. The proton-induced x-ray beam, after proper collimation, is guided to the sample position whereas various filters can be also inserted along the beam's path to eliminate the backscattered protons or/and to absorb selectively components of the x-ray beam. The apparatus incorporates an ultrathin window Si(Li) spectrometer (FWHM 136 eV at 5.89 keV) coupled with low-noise electronics capable of efficiently detecting photons down to carbon K{alpha}. Exemplary soft x-ray spectroscopy studies and results of selective x-ray fluorescence analysis are presented.

Sokaras, D. [Institute of Nuclear Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Zarkadas, Ch. [PANalytical B.V., 7600 AA Almelo (Netherlands); Fliegauf, R.; Beckhoff, B. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Karydas, A. G. [Institute of Nuclear Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Nuclear Spectrometry and Applications Laboratory, IAEA Laboratories, A-2444 Seibersdorf (Austria)

2012-12-15

33

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

Microsoft Academic Search

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

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

1995-01-01

34

Intense attosecond radiation from an X-ray FEL - extended version  

SciTech Connect

We propose the use of a ultra-relativistic electron beam interacting with a few-cycle, intense laser pulse and an intense pulse of the coherent x-rays to produce a multi-MW intensity, x-ray pulses {approx}100 attoseconds in duration. Due to a naturally-occurring frequency chirp, these pulses can be further temporally compressed.

Zholents, Alexander A.; Fawley, William M.

2003-12-01

35

Physical Analysis of High Intensity Focusing X-ray Optics: Doubly Curved Crystals vs. Highly Focusing Polycapillaries  

Microsoft Academic Search

Choosing the best performing x-ray optic for a specific x-ray fluorescence application is tricky since x-ray fluorescence requirements can vary from extremely small x-ray beams for spatially resolved measurements to intense, highly monochromatic beams for locating trace amounts of impurities in samples. Additionally, due to the wide variety of commercially available x-ray optics to choose from, each providing different outputs,

Sarah Formica; Susanne M. Lee

2002-01-01

36

Low Energy Ga Ion Beams Bombardment onside Insulating Materials and X-ray Emission  

Microsoft Academic Search

X-ray spectra from the surface of insulating samples were measured using a 30 kV Ga+ focused ion beam instrument equipped with an energy dispersive X-ray spectrometer, showing an intense emission of low energy X-rays from insulating materials such as Al-K and O-K of Al2O3. This low energy ion induced X-ray emissions (LIIXE) from insulating materials is expected as a new

Masaki Takeguchi; Renchao Che; Minghui Song; Kazuo Furuya

2007-01-01

37

Diamond photoconductive structures for positioning of X-ray beam  

Microsoft Academic Search

One-dimensional position-sensitive device prototypes were developed for monitoring the position and intensity of a continuous or chopped X-ray beam. The response in terms of linearity and sensitivity were studied on voltage division structures, in the photoconductive charge-generation regime. High-quality polycrystalline diamond samples, mechanically polished for photolithography processing, were used as photoconductor material. Chromium deposits were patterned to realize resistive elements

G. Conte; G. Mazzeo; S. Salvatori; D. Trucchi; V. Ralchenko

2005-01-01

38

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

39

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

40

Intensity correlation measurement system by picosecond single shot soft x-ray laser  

NASA Astrophysics Data System (ADS)

We developed a new soft x-ray speckle intensity correlation spectroscopy system by use of a single shot high brilliant plasma soft x-ray laser. The plasma soft x-ray laser is characterized by several picoseconds in pulse width, more than 90% special coherence, and 1011 soft x-ray photons within a single pulse. We developed a Michelson type delay pulse generator using a soft x-ray beam splitter to measure the intensity correlation of x-ray speckles from materials and succeeded in generating double coherent x-ray pulses with picosecond delay times. Moreover, we employed a high-speed soft x-ray streak camera for the picosecond time-resolved measurement of x-ray speckles caused by double coherent x-ray pulse illumination. We performed the x-ray speckle intensity correlation measurements for probing the relaxation phenomena of polarizations in polarization clusters in the paraelectric phase of the ferroelectric material BaTiO3 near its Curie temperature and verified its performance.

Kishimoto, Maki; Namikawa, Kazumichi; Sukegawa, Kouta; Yamatani, Hiroshi; Hasegawa, Noboru; Tanaka, Momoko

2010-01-01

41

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

42

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

43

Multiwavelength Anomalous Diffraction at High X-Ray Intensity  

NASA Astrophysics Data System (ADS)

The multiwavelength anomalous diffraction (MAD) method is used to determine phase information in x-ray crystallography by employing anomalous scattering from heavy atoms. X-ray free-electron lasers (FELs) show promise for revealing the structure of single molecules or nanocrystals, but the phase problem remains largely unsolved. Because of the ultrabrightness of x-ray FEL, samples experience severe electronic radiation damage, especially to heavy atoms, which hinders direct implementation of MAD with x-ray FELs. Here, we propose a generalized version of MAD phasing at high x-ray intensity. We demonstrate the existence of a Karle-Hendrickson-type equation in the high-intensity regime and calculate relevant coefficients with detailed electronic damage dynamics of heavy atoms. The present method offers a potential for ab initio structural determination in femtosecond x-ray nanocrystallography.

Son, Sang-Kil; Chapman, Henry N.; Santra, Robin

2011-11-01

44

Lattice of NSC KIPT compact intense X-ray generator NESTOR  

NASA Astrophysics Data System (ADS)

The new generation of the intense X-ray sources based on low-energy electron storage ring and Compton scattering (CS) of laser beam allows to produce X-rays with intensity up to 1014 phot/s. There are two basic problems in laser electron storage rings (LESR) design. The first one is associated with strong effect of the intrabeam scattering at low electron beam energy. Because of this effect, the beam size grows quickly and CS intensity decreases. The second problem is associated with large electron beam energy spread because of fluctuation of Compton generation. The value of the energy spread may run up to few percents and one has to keep electron beam during long term in order to achieve the high Compton beam intensity. The paper is devoted to the description of lattice of NSC KIPT compact intense X-ray generator NESTOR and the main principles are background for the LESR lattice design.

Gladkikh, P.; Ivashchernko, V.; Karnaukhov, I.; Markov, V.; Mytsykov, A.; Shcherbakov, A.; Skyrda, V.; Trotsenko, V.; Zelinsky, A.

2005-05-01

45

Two-dimensional measurement of focused hard X-ray beam profile using coherent X-ray diffraction of isolated nanoparticle  

NASA Astrophysics Data System (ADS)

A method for evaluating the two-dimensional photon density distribution in focused hard X-ray beams is proposed and demonstrated in a synchrotron experiment at SPring-8. A synchrotron X-ray beam of 11.8 keV is focused to a ˜1?m spot by Kirkpatrick-Baez mirrors. The two-dimensional intensity distribution of the focused beam is derived by monitoring the forward diffracted intensity from an isolated silver nanocube with an edge length of ˜150nm positioned in the beam waist, which is two-dimensionally scanned. Furthermore, the photon density of X-rays illuminated onto the nanocube is estimated by utilizing coherent X-ray diffraction microscopy. This method is useful for evaluating the photon density distribution of hard X-ray beams focused to a spot size of less than a few micrometers.

Takahashi, Yukio; Kubo, Hideto; Tsutsumi, Ryosuke; Sakaki, Shigeyuki; Zettsu, Nobuyuki; Nishino, Yoshinori; Ishikawa, Tetsuya; Yamauchi, Kazuto

2010-05-01

46

Two-dimensional measurement of focused hard X-ray beam profile using coherent X-ray diffraction of isolated nanoparticle  

Microsoft Academic Search

A method for evaluating the two-dimensional photon density distribution in focused hard X-ray beams is proposed and demonstrated in a synchrotron experiment at SPring-8. A synchrotron X-ray beam of 11.8keV is focused to a ?1?m spot by Kirkpatrick–Baez mirrors. The two-dimensional intensity distribution of the focused beam is derived by monitoring the forward diffracted intensity from an isolated silver nanocube

Yukio Takahashi; Hideto Kubo; Ryosuke Tsutsumi; Shigeyuki Sakaki; Nobuyuki Zettsu; Yoshinori Nishino; Tetsuya Ishikawa; Kazuto Yamauchi

2010-01-01

47

Coherent X-ray radiation produced by microbunched beams in amorphous and crystalline radiators  

NASA Astrophysics Data System (ADS)

A review on the coherent X-ray bremsstrahlung (CXBR), X-ray transition (CXTR), resonance transition (CXRTR), diffraction (CXDR), crystalline undulator (CXCUR), undulator (CXUR), channeling (CXChR) and parametric X-ray (CXPXR) radiations produced by microbunched beams passing through crystalline radiators without the accompanying SASE beams of X-ray FELs is given. Formulas for the spectral and angular distributions as well as for the total number of photons of these radiations are derived and numerically studied. It is discussed the possibility of observing of these radiations as well as their application for the study of the parameters of the electron beam microbunching which is important for the effectiveness of XFELs and for production of additional beams of intense monochromatic X-ray beams.

Ispirian, K. A.

2013-08-01

48

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

49

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

PubMed

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. PMID:23765298

Zhang, Lin; Sánchez Del Río, Manuel; Monaco, Giulio; Detlefs, Carsten; Roth, Thomas; Chumakov, Aleksandr I; Glatzel, Pieter

2013-05-08

50

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

51

Scattered X-ray beam nondestructive testing  

Microsoft Academic Search

X-ray scatter interactions generally dominate the linear attenuation coefficient at the photon energies typical of medical and industrial radiography. Specific advantages of X-ray scatter imaging, including a flexible choice of measurement geometry, direct 3D-imaging capability (tomography) and improved information for material characterization, are illustrated with results from Compton and coherent scatter devices. Applications of a Compton backscatter scanner (ComScan) in

G. Harding; J. Kosanetzky

1989-01-01

52

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

53

Laser-electron storage ring as a compact source of high-intensity X-rays  

SciTech Connect

The authors propose a laser-electron storage ring as a high-intensity x-ray source. In this compact device, an intense pulse from a high power laser, stored in a highly reflective optical resonator, repetitively Compton backscatters off a bunched electron beam that circulates in a compact storage ring. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also stabilizes the dense electron bunch against the intrabeam scattering effect in the storage ring. Thus, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible x-ray source for high-throughput x-ray lithography and many other applications.

Huang, Z.; Ruth, R.D.

1997-10-01

54

High-intensity laser synchrotron x-ray source  

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 Light Source (LSLS) concept is still waiting for a convincing demonstration. Available at the BNL`s Accelerator Test Facility (ATF), a high-brightness electron beam and the high-power C0{sub 2} laser may be used as prototype LSLS 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, 70 MeV electron bunch. Flashes of well-collimated, up to 9.36-keV ({approximately}{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 a variable e-beam energy. A natural short-term extension of the proposed experiment would be further enhancement of the x-ray flux to a 10{sup 21}{minus}10{sup 22} photons/sec level, after the ongoing ATF CO{sub 2} laser upgrade to 1 TW peak power and electron bunch shortening to 3 ps. The ATF LSLS x-ray beamline, exceeding by orders of magnitude the peak fluxes attained at the National Synchrotron Light Source (NSLS) x-ray storage ring, may become attractive for certain users, e.g., for biological x-ray microscopy. In addition, a terawatt CO{sub 2} laser will enable harmonic multiplication of the x-ray spectrum via nonlinear Compton scattering.

Pogorelsky, I.V.

1995-10-01

55

Beam line for experiments with coherent soft x-rays  

SciTech Connect

The advantages of coherent soft x-rays for three-dimensional imaging of biological specimens are discussed, the x-ray source requirements are described, and the general design of the beam line and its optical system are given. (WHK)

Howells, M.R.; Kirz, J.; Krinsky, S.

1982-12-01

56

Multilayer mirrors and beam splitters for soft X-rays  

Microsoft Academic Search

X-ray transmission coefficients for perfect multilayers have been derived based upon the optics of thin films at large angles of incidence. The new transmission coefficient together with the previously given diffraction coefficient can now be used to characterize the optical properties of multilayers. Applications of flat multilayer as X-ray beam splitters, polarizers and normal incidence mirrors are also presented.

P. Lee

1982-01-01

57

Simple X-ray cameras for beam-line instrumentation  

NASA Astrophysics Data System (ADS)

The design and performance characterization of simple X-ray cameras are shortly presented. These cameras are installed on each high-energy beam-lines of SOLEIL. Main topics, such as the choice of the scintillator, the effect of the thickness of the scintillator on the resolution, the relation between the X-ray flux and the signal, are addressed in this article.

Bordessoule, M.

2013-03-01

58

Multilayer mirrors and beam splitters for soft X-rays  

NASA Astrophysics Data System (ADS)

X-ray transmission coefficients for perfect multilayers have been derived based upon the optics of thin films at large angles of incidence. The new transmission coefficient together with the previously given diffraction coefficient can now be used to characterize the optical properties of multilayers. Applications of flat multilayer as X-ray beam splitters, polarizers and normal incidence mirrors are also presented.

Lee, P.

1982-10-01

59

X-ray lensless microscopy from undersampled diffraction intensities  

NASA Astrophysics Data System (ADS)

X-ray coherent diffraction imaging including ptychography provides the nanoscale resolved three-dimensional description of matter. The combination of these approaches to the Bragg geometry case arouses a strong interest for its capability to provide information about strain state in crystals. Among the existing approaches, ptychography is particularly appealing because it allows the investigation of extended or weakly scattering samples. Coherent diffraction imaging approaches, based on redundancy in the collected diffraction intensity data set, are highly time consuming and rely on state-of-the-art mechanical setups, both being strong limitations for a general application. We show here that these can be overcome by regularization-based inversion algorithms introducing a priori structural knowledge. This method, which can be generalized to other wavelengths or beam sources, opens new possibilities for the imaging of radiation-sensitive specimens or very large samples.

Berenguer, F.; Godard, P.; Allain, M.; Belloir, J.-M.; Talneau, A.; Ravy, S.; Chamard, V.

2013-10-01

60

High intensity pulsed plasma X-ray source  

NASA Astrophysics Data System (ADS)

The objective of the program is to perform a design study for a laser-driven, high-intensity pulsed plasma source for X-ray lithography, including a consideration of the effects of such a source on the X-ray mask structures. During this initial quarterly period, work has begun on the design for the CO2 laser driver, as well as on an analysis of the constraints imposed upon the pulsed X-ray source parameters due to thermally-induced stress damage to the mask. The complete design for the CO2 laser system must include several subsystems, the most important being the power amplifier module (PAM). During this reporting period, the conceptual design and operating parameters for the PAM have been developed, and tradeoff studies at the interfaces of support systems have been outlined. Also during this period, a scoping analysis has been performed to examine some of the influences of both x-ray source and mask geometry upon mask thermal stress constraints. Using an analytical model, parametric variation with respect to mask substrate thickness, X-ray wavelength, and X-ray pulselength has been carried out. In addition, some effects of mask configuration have been investigated. These preliminary studies are intended to give an insight into the phenomenology involved in the interaction between intense pulsed X-ray sources and potential mask damage mechanisms.

Ballantyne, A.; Friedman, H.; Hyman, H.

1981-04-01

61

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

62

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

63

An ultra fast electron beam x-ray tomography scanner  

Microsoft Academic Search

This paper introduces the design of an ultra fast x-ray tomography scanner based on electron beam technology. The scanner has been developed for two-phase flow studies where frame rates of 1 kHz and higher are required. Its functional principle is similar to that of the electron beam x-ray CT scanners used in cardiac imaging. Thus, the scanner comprises an electron

64

X-ray zone plates fabricated using electron-beam and x-ray lithography  

Microsoft Academic Search

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 raster was reduced to < 2500 A over a 2 mm x 2 mm field by applying deflection corrections, while viewing

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

1979-01-01

65

Large-distance refocusing of a submicrometre beam from an X-ray waveguide.  

PubMed

Among the several available X-ray optics for synchrotron radiation producing micrometre and submicrometre beams with high intensity, the X-ray waveguide (WG) can provide the smallest hard X-ray beam in one direction. A drawback of this optics is that, owing to the divergence at the exit, a nanometre-sized spot on the sample can only be obtained if this is within a few micrometres of the WG exit. Another limitation is that in planar WGs the beam is compressed in only one direction. Here, using a dynamically bent elliptical Si/Pt mirror, the guided X-ray beam has been refocused at approximately 1 m from the waveguide exit. The large working distance between the device and the submicrometre focus leaves some space for sample environment (vacuum chamber, furnace, cryostat, magnets, high-pressure device etc.) and allows cross-coupled geometries with two WGs for efficient compression in two directions. PMID:16371712

Lagomarsino, S; Bukreeva, I; Mocella, V; Surpi, A; Bigault, T; Cedola, A

2005-12-22

66

Ultrafast absorption of intense x rays by nitrogen molecules  

SciTech Connect

We devise a theoretical description for the response of nitrogen molecules (N{sub 2}) 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 ({Delta}SCF method). To describe the interaction with N{sub 2}, 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 N{sub 2}: 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 N{sub 2}{sup 2+}, and molecular fragmentation are explained.

Buth, Christian [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liu Jicai [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Department of Mathematics and Physics, North China Electric Power University, 102206 Beijing (China); Chen, Mau Hsiung [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Cryan, James P. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Fang Li; Hoener, Matthias; Berrah, Nora [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Glownia, James M. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Coffee, Ryan N. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

2012-06-07

67

High Intensity X-Ray Coupling to Meteorite Targets  

NASA Astrophysics Data System (ADS)

The responses of iron-nickel and stony meteorite samples to high-intensity X-ray pulses (70 - 215 GW/cm^2) pulses generated by exploding wire array hohlraums from the Sandia Z machine are reported. Induced shock waves created particle velocities of 25 - 75 m/s after rarefaction overtake, as measured by VISAR. From these values both momentum and energy coupling coefficients were obtained. These results are compared to recent high-powered-pulsed ( 1 GW/cm2 for 20 ns) 1054 nm laser induced shock pressures and momentum transfer, and energy coupling to iron-rich and stony meteorite targets (J. L. Remo et al, Laser and Particle Beams, 17, 25-44, 1999). These comparisons provide data on the scaling of shock induced effects on inhomogeneous materials in general and meteoritic materials in particular. The combination of both of these experiments extends the regime of high intensity pulsed energy deposition on non-homogeneous materials from the GW/cm^2 to 100's of GW/cm^2, providing valuable empirical insights into the shock critical equations of state and coupling responses. Application to astrophysical and geophysical modeling will be discussed.

Remo, J. L.; Furnish, M. D.; Hammerling, P.

2001-06-01

68

Ion beam sputtering of x-ray multilayer mirrors  

Microsoft Academic Search

Ion beam sputtering has been applied for polishing, figuring and multilayer coating on silicon and quartz glass substrates for the fabrication of x-ray mirrors. For high-performance x-ray optics extremely low microroughnesses of the substrates have to be achieved. Particularly for low d-spacing multilayers (d = 1...2 nm) even small improvements of the surface quality result in significant performance gains of

Peter Gawlitza; Stefan Braun; Georg Dietrich; Maik Menzel; Stefan Schädlich; Andreas Leson

2008-01-01

69

High intensity line source for x-ray spectrometer calibration  

SciTech Connect

A high intensity electron-impact x-ray source using a one-dimensional Pierce lens has been built for the purpose of calibrating a bent crystal x-ray spectrometer. This source focuses up to 100 mA of 20-keV electrons to a line on a liquid-cooled anode. The line (which can serve as a virtual slit for the spectrometer) measures approximately 800 ..mu.. x 2 cm. The source is portable and therefore adaptable to numerous types of spectrometer applications. One particular application, the calibration of a high resolution (r = 10/sup 4/) time-resolved cyrstal spectrometer, will be discussed in detail.

Thoe, R.S.

1986-06-01

70

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

Microsoft Academic Search

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

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

2004-01-01

71

Research on temperature measurement by X-ray transmission intensity  

NASA Astrophysics Data System (ADS)

The relationship between temperature and X-ray transmission intensity was researched and analyzed by inspecting material density change, which is caused by thermal expansion. A digital radiographic system was employed to obtain the images. On this basis, we deduced the temperature formula based on the average gray level of the captured images. The measured temperatures were obtained from the experiments and the errors were analyzed. We concluded that when X-rays pass through an object, the X-ray strength and the gray level of the image under high temperatures are greater than those under lower temperatures and the image gray level error has great impact on the accuracy of the measured temperature. The presented approach allowed the non-contact temperature measurement of material.

Chen, Shuyue; Cheng, Rong

2013-02-01

72

A Experimental Measurement of Metal Multilayer X-Ray Reflectivity Degradation due to Intense X-Ray Flux  

Microsoft Academic Search

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-

Mary Yvonne Pottenger Hockaday

1986-01-01

73

X-ray Methods in High-Intensity Discharges and Metal-Halide Lamps: X-ray Induced Fluorescence  

SciTech Connect

We describe the use of x-ray induced fluorescence to study metal-halide high-intensity discharge lamps and to measure equilibrium vapor pressures of metal-halide salts. The physical principles of metal-halide lamps, relevant aspects of x-ray-atom interactions, the experimental method using synchrotron radiation, and x-ray induced fluorescence measurements relevant to metal-halide lamps are covered.

Curry, John J.; Lapatovich, Walter P.; Henins, Albert (NIST)

2011-12-09

74

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

75

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

76

Monochromators for small cross-section x-ray beams from high heat flux synchrotron sources  

SciTech Connect

For some x-ray experiments, only a fraction of the intense central cone of x-rays generated by high-power undulator sources can be used; the x-ray source emittance is larger than the useful emittance for the experiment. For example with microfocusing optics, or for coherence experiments, x-ray beams with cross sections less than 0.1 mm{sup 2} are desirable. With such small beams, the total thermal load is small even though the heat flux density is high. Analyses indicate that under these conditions, rather simple crystal cooling techniques can be used. We illustrate the advantages of a small beam monochromator, with a simple x-ray monochromator optimized for x-ray microdiffraction. This monochromator is designed to achieve negligible distortion when subjected to a narrow (0.1 mm wide) beam from an APS undulator operating at 100 mA. It also allows for rapid and repeatable energy scans and rapid cycling between monochromatic and white beam conditions.

Ice, G.; Riemer, B. [Oak Ridge National Lab., TN (United States); Khounsary, A. [Argonne National Lab., IL (United States)

1996-10-01

77

{sup 30}S Beam Development and X-ray Bursts  

SciTech Connect

Over the past three years, we have worked on developing a well-characterized {sup 30}S radioactive beam to be used in a future experiment aiming to directly measure to extrapolate the {sup 30}S(alpha,p) stellar reaction rate within the Gamow window of Type I X-ray bursts. The importance of the {sup 30}S(alpha,p) reaction to X-ray bursts is discussed. Given the astrophysical motivation, the successful results of and challenges involved in the production of a low-energy {sup 30}S beam are detailed. Finally, an overview of our future plans regarding this on-going project are presented.

Kahl, D.; Kubono, S.; Binh, D. N.; Hashimoto, T.; Hayakawa, S.; Kurihara, Y.; Ohshiro, Y.; Yamaguchi, H. [Center for Nuclear Study (CNS), University of Tokyo, Wako, Saitama, 351-0198 (Japan); Chen, A. A.; Chen, J.; Setoodeh nia, K. [Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, L8S-4M1 (Canada); Kaji, D.; Nishimura, S. [RIKEN, Institute of Physical and Chemical Research, Wako, Saitama, 351-0198 (Japan); Kim, A.; Lee, N. H. [Department of Physics, Ewha Womans University, Seoul 120-750 (Korea, Republic of); Wakabayashi, Y. [Center for Nuclear Study (CNS), University of Tokyo, Wako, Saitama, 351-0198 (Japan); Advanced Science Research Center, Japan Atomic Energy Agency (JAEA), Naka-gun, Ibaraki 319-1195 (Japan)

2010-03-01

78

Relative intensity of the K?5 X-ray line  

NASA Astrophysics Data System (ADS)

The relative intensity of the K?5 (K-MIV,V) X-ray line as a function of the atomic number of the emitting elements is very strongly enhanced around Z = 24 (chromium) relative to predictions of the single-particle model for this electric dipole (El) forbidden transition. The enhancement is attributed to solid state or chemical effects. The K?5 transition can be El-allowed because in chemical compounds the outermost 3d level forms the valence shells, while in metals it becomes a broad band. The intensity of this line can therefore vary with the chemical state. We have determined the K?5/K?1 intensity ratio that results from proton impact on Ca, Ti and Cr, and we have collected the experimental data available in the literature. The influence of the sharp increase in the K?5 intensity on the K?/K? intensity ratio and on X-ray analytical methods (e.g. proton induced X-ray emission, electron probe microanalysis, etc.) is discussed.

Török, I.; Papp, T.; Pálinkás, J.; Budnar, M.; Mühleisen, A.; Kawai, J.; Campbell, J. L.

1996-06-01

79

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

80

An ultra fast electron beam x-ray tomography scanner  

NASA Astrophysics Data System (ADS)

This paper introduces the design of an ultra fast x-ray tomography scanner based on electron beam technology. The scanner has been developed for two-phase flow studies where frame rates of 1 kHz and higher are required. Its functional principle is similar to that of the electron beam x-ray CT scanners used in cardiac imaging. Thus, the scanner comprises an electron beam generator with a fast beam deflection unit, a semicircular x-ray production target made of tungsten alloy and a circular x-ray detector consisting of 240 CZT elements with 1.5 mm × 1.5 mm × 1.5 mm size each. The design is optimized with respect to ultra fast imaging of smaller flow vessels, such as pipes or laboratory-scale chemical reactors. In that way, the scanner is capable of scanning flow cross-sections at a speed of a few thousand frames per second which is sufficient to capture flows of a few meters per second velocity.

Fischer, F.; Hoppe, D.; Schleicher, E.; Mattausch, G.; Flaske, H.; Bartel, R.; Hampel, U.

2008-09-01

81

Editorial: Focus on X-ray Beams with High Coherence  

Microsoft Academic Search

This editorial serves as the preface to a special issue of New Journal of Physics, which collects together solicited papers on a common subject, x-ray beams with high coherence. We summarize the issue's content, and explain why there is so much current interest both in the sources themselves and in the applications to the study of the structure of matter

Ian Robinson; Gerhard Gruebel; Simon Mochrie

2010-01-01

82

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

83

Imaging quality assessment of multiplexing x-ray radiography based on multi-beam x-ray source technology  

NASA Astrophysics Data System (ADS)

Multiplexing technique has been widely used in telecommunication, magnetic resonance imaging (MRI) and various spectroscopic applications to drastically increase system throughput. In the field of radiology, however, it was just getting started to attract researchers' attention recently due to the development of multi-beam x-ray source technology, especially the emergence of carbon nanotube (CNT) field emission based multi-beam x-ray source. The CNT multi-beam x-ray source provides an ideal signal source for multiplexing x-ray imaging applications because of its capability of modulating x-ray radiation waveforms. The feasibility of multiplexing x-ray radiography has been successfully demonstrated experimentally using a CNT field emission enabled multi-beam x-ray imaging system. The idea of applying multiplexing radiography in computed tomography (CT) to speed up scanning speed has also been proposed. At the same time several simulation studies on the evaluation of multiplexing x-ray imaging performance have been reported. In this study, we reported our recent investigation on the imaging quality assessment of multiplexing xray radiography based on the simulation work stimulated by our previous experimental experience. A computer program was written to simulate the imaging process of the as-developed multi-beam x-ray imaging system. The impacts of different noise components on multiplexing imaging quality were studied. Our preliminary results indicated that the performance of multiplexing x-ray radiography is closely related to the noise environment and x-ray tube current stability. Under appropriate imaging conditions, multiplexing radiography has the potential to achieve higher imaging speed without significantly sacrificing the imaging quality.

Zhang, J.; Peng, R.; Chang, S.; Lu, J. P.; Zhou, O.

2010-03-01

84

X-ray monochromator for divergent beam radiography using conventional and laser-produced x-ray sources  

Microsoft Academic Search

We discuss technology that will produce a wide angle monochromatic beam of X-rays that appears to diverge from a virtual point source. Although our ideas are discussed in the context of dual energy subtraction angiography (DESA) that we are developing to operate in a clinical setting, they are widely adaptable to all applications of x-ray radiography. The best DESA analysis

Herbert W. Schnopper; Suzanne E. Romaine; Andrzej Krol

2001-01-01

85

A simple hard x-ray ''nanoslit'' for measuring wavefront intensity  

SciTech Connect

A new method is proposed for nanoscale hard x-ray measurements. This method uses a reflection on a heavy-metal wire that functions as a single slit with a nanoscale aperture for a parallel x-ray beam. This ''nanoslit'' can be used to perform high-spatial-resolution measurements of the intensity distribution of a wavefront that diverges from an aperture. In experiments, Fresnel fringes generated by a rectangular aperture were measured using a 300-{mu}m-diameter platinum wire as the nanoslit. In these experiments, the finest fringes with a period of 26 nm could be successfully resolved.

Takano, Hidekazu; Hashimoto, Takuto; Tsuji, Takuya; Koyama, Takahisa; Tsusaka, Yoshiyuki; Kagoshima, Yasushi [Graduate School of Material Science, University of Hyogo, Kouto 3-2-1, Hyogo 678-1297 (Japan)

2010-07-15

86

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

87

Microdosimetric characteristics of micro X-ray beam for single cell irradiation  

Microsoft Academic Search

A tabletop micro X-ray beam irradiation system has been developed to study radiation effects on living cells. The microbeam system is composed of a micro focus X-ray tube, a capillary for X-ray guide, an X-ray semiconductor detector for fluorescent X-ray analysis, and an inverted microscope. A beam profile measurement was performed and the size of the focused beam was 10

T. Kuchimaru; F. Sato; Y. Higashino; K. Shimizu; Y. Kato; T. Iida

2006-01-01

88

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

SciTech Connect

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.

Rodrigues, G.; Lakshmy, P. S.; Kanjilal, D.; Roy, A. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Baskaran, R. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603102, Tamilnadu (India)

2010-02-15

89

Imaging quality assessment of multiplexing x-ray radiography based on multi-beam x-ray source technology  

Microsoft Academic Search

Multiplexing technique has been widely used in telecommunication, magnetic resonance imaging (MRI) and various spectroscopic applications to drastically increase system throughput. In the field of radiology, however, it was just getting started to attract researchers' attention recently due to the development of multi-beam x-ray source technology, especially the emergence of carbon nanotube (CNT) field emission based multi-beam x-ray source. The

J. Zhang; R. Peng; S. Chang; J. P. Lu; O. Zhou

2010-01-01

90

Atomic Physics Using Ultra-Intense X-Ray Pulses  

NASA Astrophysics Data System (ADS)

The combination of short wavelengths and ultrahigh intensities as provided by the new soft and hard X-ray free electron laser sources opens the doorway to totally new experiments on photon-matter interaction. It concerns, in particular, new classes of nonlinear inner-atomic processes. In the present contribution, recent results on sequential and nonsequential multi-photon ionization of gas phase targets are presented and discussed; including processes where also inner shells are affected. Moreover, examples are given how linear and nonlinear photoionization may be used for online photon diagnostics at these new radiation sources.

Martins, M.; Meyer, M.; Richter, M.; Sorokin, A. A.; Tiedtke, K.

91

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

92

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

NASA Astrophysics Data System (ADS)

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; Uhlén, Fredrik; Vogt, Ulrich; Hertz, Hans M.; Schroer, Christian G.

2013-04-01

93

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

94

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

95

Editorial: Focus on X-ray Beams with High Coherence  

NASA Astrophysics Data System (ADS)

This editorial serves as the preface to a special issue of New Journal of Physics, which collects together solicited papers on a common subject, x-ray beams with high coherence. We summarize the issue's content, and explain why there is so much current interest both in the sources themselves and in the applications to the study of the structure of matter and its fluctuations (both spontaneous and driven). As this collection demonstrates, the field brings together accelerator physics in the design of new sources, particle physics in the design of detectors, and chemical and materials scientists who make use of the coherent beams produced. Focus on X-ray Beams with High Coherence Contents Femtosecond pulse x-ray imaging with a large field of view B Pfau, C M Günther, S Schaffert, R Mitzner, B Siemer, S Roling, H Zacharias, O Kutz, I Rudolph, R Treusch and S Eisebitt The FERMI@Elettra free-electron-laser source for coherent x-ray physics: photon properties, beam transport system and applications E Allaria, C Callegari, D Cocco, W M Fawley, M Kiskinova, C Masciovecchio and F Parmigiani Beyond simple exponential correlation functions and equilibrium dynamics in x-ray photon correlation spectroscopy Anders Madsen, Robert L Leheny, Hongyu Guo, Michael Sprung and Orsolya Czakkel The Coherent X-ray Imaging (CXI) instrument at the Linac Coherent Light Source (LCLS) Sébastien Boutet and Garth J Williams Dynamics and rheology under continuous shear flow studied by x-ray photon correlation spectroscopy Andrei Fluerasu, Pawel Kwasniewski, Chiara Caronna, Fanny Destremaut, Jean-Baptiste Salmon and Anders Madsen Exploration of crystal strains using coherent x-ray diffraction Wonsuk Cha, Sanghoon Song, Nak Cheon Jeong, Ross Harder, Kyung Byung Yoon, Ian K Robinson and Hyunjung Kim Coherence properties of the European XFEL G Geloni, E Saldin, L Samoylova, E Schneidmiller, H Sinn, Th Tschentscher and M Yurkov Fresnel coherent diffractive imaging: treatment and analysis of data G J Williams, H M Quiney, A G Peele and K A Nugent Imaging of complex density in silver nanocubes by coherent x-ray diffraction R Harder, M Liang, Y Sun, Y Xia and I K Robinson Methodology for studying strain inhomogeneities in polycrystalline thin films during in situ thermal loading using coherent x-ray diffraction N Vaxelaire, H Proudhon, S Labat, C Kirchlechner, J Keckes, V Jacques, S Ravy, S Forest and O Thomas Ptychographic coherent diffractive imaging of weakly scattering specimens Martin Dierolf, Pierre Thibault, Andreas Menzel, Cameron M Kewish, Konstantins Jefimovs, Ilme Schlichting, Konstanze von König, Oliver Bunk and Franz Pfeiffer Dose requirements for resolving a given feature in an object by coherent x-ray diffraction imaging Andreas Schropp and Christian G Schroer FLASH: new opportunities for (time-resolved) coherent imaging of nanostructures R Treusch and J Feldhaus Structure of a single particle from scattering by many particles randomly oriented about an axis: toward structure solution without crystallization? D K Saldin, V L Shneerson, M R Howells, S Marchesini, H N Chapman, M Bogan, D Shapiro, R A Kirian, U Weierstall, K E Schmidt and J C H Spence Analysis of strain and stacking faults in single nanowires using Bragg coherent diffraction imaging V Favre-Nicolin, F Mastropietro, J Eymery, D Camacho, Y M Niquet, B M Borg, M E Messing, L-E Wernersson, R E Algra, E P A M Bakkers, T H Metzger, R Harder and I K Robinson Coherent science at the SwissFEL x-ray laser B D Patterson, R Abela, H-H Braun, U Flechsig, R Ganter, Y Kim, E Kirk, A Oppelt, M Pedrozzi, S Reiche, L Rivkin, Th Schmidt, B Schmitt, V N Strocov, S Tsujino and A F Wrulich Energy recovery linac (ERL) coherent hard x-ray sources Donald H Bilderback, Joel D Brock, Darren S Dale, Kenneth D Finkelstein, Mark A Pfeifer and Sol M Gruner Statistical and coherence properties of radiation from x-ray free-electron lasers E L Saldin, E A Schneidmiller and M V Yurkov Microscopic return point memory in Co/Pd multilayer films K A Seu, R Su, S Roy, D Parks, E Shipton, E E Fullerton and S D Kevan Hol

Robinson, Ian; Gruebel, Gerhard; Mochrie, Simon

2010-03-01

96

A single-shot intensity-position monitor for hard x-ray FEL sources  

Microsoft Academic Search

An inline diagnostics device was developed to measure the intrinsic shot-to-shot intensity and position fluctuations of the SASE-based LCLS hard X-ray FEL source. The device is based on the detection of back-scattered X-rays from a partially-transmissive thin target using a quadrant X-ray diode array. This intensity and position monitor was tested for the first time with FEL X-rays on the

Yiping Feng; Jan M. Feldkamp; David M. Fritz; Marco Cammarata; Robert Aymeric; Chiara Caronna; Henrik T. Lemke; Diling Zhu; Sooheyong Lee; Sebastien Boutet; Garth Williams; Kensuke Tono; Makina Yabashi; Jerome B. Hastings

2011-01-01

97

Demonstration of amplification of a polarized soft-x-ray laser beam in a neonlike germanium plasma  

Microsoft Academic Search

We report results of polarization experiments on the collisionally excited Ne-like Ge soft-x-ray laser where we have used an injector-amplifier multistage geometry. The polarization state of the x-ray beam was analyzed by two crossed 45° angle of incidence multilayer mirrors which act as linear polarizers. Results were evaluated by comparing intensities of time-integrated beam patterns behind each polarizer. The polarization

B. Rus; C. L. S. Lewis; G. F. Cairns; P. Dhez; P. Jaeglé; M. H. Key; D. Neely; A. G. Macphee; S. A. Ramsden; C. G. Smith; A. Sureau

1995-01-01

98

L X-ray Intensity Ratios in Pb With Protons  

SciTech Connect

Accelerators play a significant role in the investigation of inner-shell ionization. Inner-shell excitation through the impact of protons has shown renewed interest recently. These studies indicate that in the case of L-shell ionization, most of the experiments have been conducted with protons having energies greater than 500 keV. Thus, there is not only a lack of experimental data but there also exists large discrepancies between the experimental measurements and the theoretical calculations based on different models prevailing in this energy regime. In view of this, we report in this paper the experimentally measured values of L X-ray intensity ratios for Pb, namely, L{sub l}/L{sub {alpha}}, L{sub {beta}}/L{sub {alpha}} and L{sub {gamma}}/L{sub {alpha}} with protons over the energy range 225 keV-400 keV using a Van de Graaff accelerator. Their energy dependence and comparison with theoretical calculations will also be discussed. These measurements have yielded data in the low energy region, which helps in the emergence of better understanding of proton induced X-ray emission phenomenon.

Mohan, Harsh; Jain, Arvind Kumar [Physics Department, M.L.N. College, Yamuna Nagar 135 001, Haryana (India); Sharma, Sunita [Chemistry Department, M.L.N. College, Yamuna Nagar 135 001, Haryana (India)

2009-03-10

99

L X-ray Intensity Ratios in Pb With Protons  

NASA Astrophysics Data System (ADS)

Accelerators play a significant role in the investigation of inner-shell ionization. Inner-shell excitation through the impact of protons has shown renewed interest recently. These studies indicate that in the case of L-shell ionization, most of the experiments have been conducted with protons having energies greater than 500 keV. Thus, there is not only a lack of experimental data but there also exists large discrepancies between the experimental measurements and the theoretical calculations based on different models prevailing in this energy regime. In view of this, we report in this paper the experimentally measured values of L X-ray intensity ratios for Pb, namely, L/L?, L?/L? and L?/L? with protons over the energy range 225 keV-400 keV using a Van de Graaff accelerator. Their energy dependence and comparison with theoretical calculations will also be discussed. These measurements have yielded data in the low energy region, which helps in the emergence of better understanding of proton induced X-ray emission phenomenon.

Mohan, Harsh; Jain, Arvind Kumar; Sharma, Sunita

2009-03-01

100

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

101

Analysis and design of precision optical components in high-intensity, third-generation x-ray beamlines  

Microsoft Academic Search

A novel mounting and cryogenic coolant manifold system to minimize sub-micron mounting strains and improve the sealing of the liquid nitrogen coolant in the ultra-high- vacuum environment of high-intensity x-ray beamlines is proposed. A unique method to accurately simulate the complex interaction of the x-ray beam with the silicon monochromator and the subsequent thermal distortion is presented. Silicon crystal monochromators

Gordon Chikao Tajiri

2001-01-01

102

X-ray pencil beam facility for optics characterization  

NASA Astrophysics Data System (ADS)

The Physikalisch-Technische Bundesanstalt (PTB) has used synchrotron radiation for the characterization of optics and detectors for astrophysical X-ray telescopes for more than 20 years. At a dedicated beamline at BESSY II, a monochromatic pencil beam is used by ESA and cosine Research since the end of 2005 for the characterization of novel silicon pore optics, currently under development for the International X-ray Observatory (IXO). At this beamline, a photon energy of 2.8 keV is selected by a Si channel-cut monochromator. Two apertures at distances of 12.2 m and 30.5 m from the dipole source form a pencil beam with a typical diameter of 100 ?m and a divergence below 1". The optics to be investigated is placed in a vacuum chamber on a hexapod, the angular positioning is controlled by means of autocollimators to below 1". The reflected beam is registered at 5 m distance from the optics with a CCD-based camera system. This contribution presents design and performance of the upgrade of this beamline to cope with the updated design for IXO. The distance between optics and detector can now be 20 m. For double reflection from an X-ray Optical Unit (XOU) and incidence angles up to 1.4°, this corresponds to a vertical translation of the camera by 2 m. To achieve high reflectance at this angle even with uncoated silicon, a lower photon energy of 1 keV is available from a pair of W/B4C multilayers. For coated optics, a high energy option can provide a pencil beam of 7.6 keV radiation.

Krumrey, Michael; Cibik, Levent; Müller, Peter; Bavdaz, Marcos; Wille, Eric; Ackermann, Marcelo; Collon, Maximilien J.

2010-07-01

103

Optimization of radiography applications using x-ray beams emitted by compact accelerators. Part I. Monte Carlo study of the hard x-ray spectrum  

SciTech Connect

Purpose: A 3-year project called LABSYNC has been recently funded by the European Commission, with the aim of designing a radiation facility based on a compact light source, i.e., a laboratory-sized commercial synchrotron, capable of accelerating electrons up to 6 or 20 MeV. An accurate spectral description of hard x rays emitted from thin targets, irradiated by electron beams circulating in the storage ring, is of primary interest for the design and the characterization of a beamline. This article, Part I, aims at optimizing some of the parameters which are critical for the design of medical applications based on the above compact light source. The goal was to evaluate the dependence of photon fluence and beam monochromaticity on electron-beam energy, target material, and thickness. Methods: The transport of 6 and 20 MeV electrons in a thin molybdenum, rhodium, and tungsten target is studied by means of Monte Carlo simulations using MCNPX. Configurations of the x-ray output port, different from the default forward-directed emission of the beam, are also investigated. A comparison with reference spectra for general diagnostic radiology and mammography is carried out. Results: It is shown that the emitted x-ray beams can be far more intense than those generated by conventional x-ray tubes for radiography applications. The profiles of the calculated polychromatic spectra resemble those generated by conventional x-ray tubes, with x-ray energies up to the energy of the incident-electron beam. An appreciable improvement in the monochromaticity of the beams can be obtained by viewing the x-ray emission from an output port antiparallel to the direction of the incident-electron beam. Conclusions: The optimum target thickness for tungsten target spectra is practically constrained by a trade-off between bremsstrahlung efficiency and focal-spot size requirements. A larger margin for optimization of target thickness is probably available for mammographic spectra. The constraint of a backward-directed (or, to a lesser extent, orthogonal) output port is to be considered mandatory for minimizing the high-energy tail of the spectral distribution and keeping the radiation dose to a reasonable level. It is also fundamental to evaluate the impact of the high-energy tail of the emitted spectra in x-ray imaging applications, since the energy range involved is significantly beyond the diagnostic range. This topic will be dealt with in Part II of the article.

Marziani, M.; Taibi, A.; Di Domenico, G.; Gambaccini, M. [Dipartimento di Fisica, Universita di Ferrara, Ferrara FE-44100 (Italy) and INFN, Ferrara FE-44100 (Italy)

2009-10-15

104

X-ray micro-beam study of reliability in aluminum-copper interconnect lines  

NASA Astrophysics Data System (ADS)

X-ray photoemission spectroscopy and x-ray diffraction are powerful techniques widely used in materials research. The advent of synchrotron radiation facilities as high brightness x-ray sources and recent advances in x-ray optics have extended these techniques to spatially resolved measurements with sub-micron resolution. We have used two such facilities to study two major reliability problems in integrated circuit interconnect technology: electromigration and mechanical stress induced problems. MAXIMUM at the Advanced Light Source (ALS) is a scanning photoemission microscope based on multilayer coated normal incidence optics. It acquires images of surfaces that map chosen spectral features from photoelectron emission spectra. In situ electromigration experiments were performed in the ultra high vacuum chamber of MAXIMUM on patterned Al-Cu lines. The results demonstrate a Cu rich surface precipitation, changes in Cu distribution as a result of the electromigration process and the detection of shallow voids under the surface oxide layer. The X-ray micro-beam facility at the Advanced Photon Source (APS) uses diffractive Fresnel Zone Plates to focus intense undulator light into a sub-micron size beam. Microdiffraction experiments were performed to map the stress distribution along patterned Al-Cu lines with a ˜1 ?m resolution for the first time. Diffraction patterns from single grains were recorded on an x-ray CCD camera and techniques developed to analyze the two dimensional micro-diffraction data for strain-stress analysis. An increase of grain to grain and intra-grain stress variation was found after accelerated electromigration testing. Contrary to predictions, no long range variation of stress due to electromigration was observed. These observations demonstrate the usefulness and potential of x-ray micro-characterization techniques in the electronic materials area.

Solak, Harun Hadi

105

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

106

The effects of laser beam non-uniformities on x-ray conversion efficiency  

SciTech Connect

High gain Inertial Confinement Fusion (ICF) targets require a highly uniform drive. In the case of direct drive, the inherent non-uniformities in a high-power glass laser beam are large enough to prevent high compression of targets. In recent years two methods for smoothing the laser drive, Induced Spatial Incoherence (ISI) and Smoothing by Spectral Dispersion (SSD), have been proposed. Both methods break the original laser beam up into many beamlets that then interfere at the target to produce an illumination pattern with large instantaneous intensity variations over a wide range of spatial scales. This interferences pattern dances around at the coherence time of the laser and averages out to produce a smooth beam on longer time scales. Indirect drive schemes shine the laser on high-Z material, usually gold, which converts the laser energy into x-rays. The x-rays are then used to drive the target. Non-uniformities in the laser beam can imprint themselves on the emitted x-rays and potentially cause problems, although the spatial transport of the x-rays to the target tends to smooth out these non-uniformities. As a result, ISI and SSD schemes are also being considered for indirect drive laser systems. We address this problem by modeling the effects on the x-ray conversion efficiency of shining a laser beam with a sinusoidal intensity modulation on a gold slab. Our principal results are that electron heat transport is quite efficient in smoothing out non-uniformities in the laser deposition before they reach the ablation surface if the spatial scale of the laser modulation is less than roughly 500 {mu}m. We also show that the gold plasma is below the Raman and Brillouin thresholds throughout the pulse.

Langer, S.H.; Estabrook, K.G.

1990-11-05

107

Adhesion improvement in the deep X-ray lithography process using a central beam-stop  

NASA Astrophysics Data System (ADS)

In deep X-ray lithography, adhesion problems of resist structures are correlated to the spectral distribution of the synchrotron radiation source. For high energy sources, the contrast of an X-ray mask might become insufficient. This appears as a severe problem when the deep lithography process is used for mask replication involving a lower resist thickness on the order of a few tens of micrometers. To reduce the proportion of high energy photons in the radiation spectrum, a simple hard X-ray filtering system was developed. The central part of the vertical intensity distribution is blocked by a beam-stop acting as a low energy band-pass filter. Experiments with this device demonstrate an improved adhesion of 50?m thick PMMA microstructures on a TiOx-plating base.

Pérennès, F.; Pantenburg, F. J.

2001-04-01

108

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

109

Development of a Scanning X-ray Fluorescence Microscope Using Size-Controllable Focused X-ray Beam from 50 to 1500nm  

SciTech Connect

In scanning X-ray microscopy, focused beam intensity and size are very important from the viewpoints of improvements of various performances such as sensitivity and spatial resolution. The K-B mirror optical system is considered to be the most promising method for hard X-ray focusing, allowing highly efficient and energy-tunable focusing. We developed focusing optical system using K-B mirrors where the focused beam size is controllable within the range of 50 - 1500 nm. The focused beam size and beam intensity can be adjusted by changing the source size, although beam intensity and size are in a trade-off relationship. This controllability provides convenience for microscopy application. Diffraction limited focal size is also achieved by setting the source size to 10 {mu}m. Intracellular elemental mappings at the single-cell level were performed to demonstrate the performance of the scanning X-ray fluorescence microscope equipped with the optical system at the BL29XUL of SPring-8. We will show magnified elemental images with spatial resolution of {approx}70 nm.

Matsuyama, Satoshi; Mimura, Hidekazu; Yumoto, Hirokatsu; Katagishi, Keiko; Handa, Soichiro; Shibatani, Akihiko; Sano, Yasuhisa; Yamauchi, Kazuto [Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871 (Japan); Yamamura, Kazuya; Endo, Katsuyoshi; Mori, Yuzo [Research Center for Ultra-Precision Science and Technology, Graduate School of Engineering, Osaka University, Yamada-oka 2-1, Suita, Osaka 565-0871 (Japan); Nishino, Yoshinori; Tamasaku, Kenji [SPring-8/RIKEN, Kouto 1-1-1, Mikazuki, Hyogo 679-5148 (Japan); Yabashi, Makina [SPring-8/Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Mikazuki, Hyogo 679-5148 (Japan); Ishikawa, Tetsuya [SPring-8/Japan Synchrotron Radiation Research Institute (JASRI), Kouto 1-1-1, Mikazuki, Hyogo 679-5148 (Japan); SPring-8/RIKEN, Kouto 1-1-1, Mikazuki, Hyogo 679-5148 (Japan)

2007-01-19

110

Intensity correlation measurement system by picosecond single shot soft x-ray laser  

Microsoft Academic Search

We developed a new soft x-ray speckle intensity correlation spectroscopy system by use of a single shot high brilliant plasma soft x-ray laser. The plasma soft x-ray laser is characterized by several picoseconds in pulse width, more than 90% special coherence, and 1011 soft x-ray photons within a single pulse. We developed a Michelson type delay pulse generator using a

Maki Kishimoto; Kazumichi Namikawa; Kouta Sukegawa; Hiroshi Yamatani; Noboru Hasegawa; Momoko Tanaka

2010-01-01

111

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

112

Intense Soft X-ray Production By Plasma Discharge Bombardment of a Deuterated Target  

NASA Astrophysics Data System (ADS)

Intense soft (1-2 keV) X-ray emission was recently observed from a metal target such as Ti or Pd which serves as the cathode in a high current, pulsed deuterium plasma discharge tube[1]. These experimental results are briefly reviewed here along with the design and inital operation of a new experiment at the U of Illinois. This unique configuration provides a significantly higher intensity of soft x-rays than previously reported for conventional accelerator ion beam bombardment of metal targets. It is proposed that the high emission in present experiments is related to anomalous transfer of energy through recoil events when a highly loaded (large D/metal atom ratio) metal hydride is bombarded with the very high current ion beam obtained via a pulsed plasma discharge (vs. lower current accelerators). Then energy associated with the deuteron desorption/flow from the overheated cathode surface creates non-equilibrium lattice phonons, which in turn excite a "metastable" super-cell state in the loaded metal. [1] A.G. Lipson, A.S. Roussetski, A.B. Karabut, G.H. Miley, "Enhancement of DD-reaction and X-ray Generation in High-Current Deuterium Glow Discharge at Voltages 0.8-2.5 kV", JETP Lett.,(2003).

Yang, Yang; Miley, George H.; Lipson, Andrei; Luo, Nie; Karabut, Alexander

2004-11-01

113

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

114

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

115

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 must address competing performance requirements. In addition to high X-ray energy, 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. We report here

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

2009-01-01

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

A spherical compound refractive lens to control x-ray beams  

Microsoft Academic Search

Compound refractive X-ray lens, consisting of a lot number of placed in-line concave microlenses, is a unique device to control X-ray beams. It works like ordinary refractive lens for visual light and, in contrast to other X-ray optical devices, is useful for forming image of X-ray source. The size of the source image S1 depends on the distance a between

G. Cappuccio; Sultan B. Dabagov; Dariush Hampai; Yury I. Dudchik; Fadei F. Komarov

2007-01-01

118

Characterization of linear accelerator X-ray source size using a laminated beam-spot camera.  

PubMed

A laminated beam-spot camera of length 20 cm and effective cross-sectional area 2.5 cm × 3 cm was designed and constructed for the measurement of X-ray beam-spot sizes on different models of Siemens accelerators. With the accelerator gantry at 180° and camera positioned on an accessory tray holder, an XV film placed in contact with the camera at the distal end of it detected those X-rays that were transmitted through the camera. The FWHM of the detected X-ray intensity profile in the gun-target (G-T) direction or the orthogonal A-B direction was used as a measure of the beam-spot size in that direction. Siemens Mevatron MXEs exhibited a beam-spot size of 1.7 ± 0.2 mm in both the in-plane and cross-plane directions for 6 MV photon beams. The beam-spot size observed for a Mevatron MDX-2 was larger by up to 1 mm, and also was different for the in-plane and cross-plane directions. For Siemens PRIMUS accelerators, the beam-spot size in the in-plane direction was found to fall in the range 2.0-2.2 ± 0.2 mm, whereas the beam-spot size in the cross-plane direction fell within 1.7-1.9 ± 0.2 mm for 6, 10, and 18 MV photon beams. Assessment of long-term stability of the beam-spot size shows the spot size remains fairly stable over time. PMID:21844857

Yeboah, Collins

2011-05-10

119

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

120

X-Ray Emission from the Metastable Components of Slow Ar16+ Beam on Metallic Surfaces  

NASA Astrophysics Data System (ADS)

K-shell X-ray emission was observed in the neutralization process of Ar16+ interacting with beryllium and molybdenum at slow speed (less than Bohr velocity). The K-shell X-ray emission came from the metastable component of Ar16+ beam with the configuration (1s2s) produced from electron cyclotron resonance ion source. The intensity ratio of K? X-ray emission to K? X-ray emission (IK?/IK?) in the neutralization process decreased when the kinetic energy of the projectile increased. This is closely related to the flight time the projectiles spend above the surface, which is dominated by both the work function of the metal and the normal velocity component of the incident ions to the surface according to the classical over-barrier model. As the relation between IK?/IK? and the above-flight time shows, the longer time above the surface the larger ratio due to the above-surface contribution. Furthermore, the smaller work function leads to the smaller contribution from the above surface.

Zhang, H. Q.; Chen, X. M.; Liu, Z. Y.; Yang, Z. H.; Xu, J. Z.; Cui, Y.; Xu, X.; Shao, J. X.; Zhang, X. A.; Zhao, Y. T.; Zhang, Y. P.; Xiao, G. Q.

121

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

122

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

123

Experimental investigation of beam heating in a soft X-ray scanning transmission X-ray microscope.  

PubMed

A variable temperature sample holder with an operational range of 15 to 200 °C and an accuracy of ±1 °C has been fabricated for scanning transmission X-ray microscopes (STXM). Here we describe the device, and use it to image the polycrystalline morphology of solid stearic acid and palmitic acid at temperatures near their respective melting points as a means of checking for possible sample heating caused by the focused X-ray beam. The melting points observed in STXM were identical to those observed by conventional methods within measurement uncertainty, even under the most extreme, high dose rate imaging conditions investigated. The beam-induced temperature rise in the sample is inferred to be below 1 °C for dose rates of up to 2.7 GGy/s. PMID:22080936

Leontowich, Adam F G; Hitchcock, Adam P

2011-11-14

124

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

125

Time Integrated Soft X-ray Imaging in High Intensity Laser Experiments (thesis)  

SciTech Connect

2009 marks a significant achievement and the dawn of a new era in high intensity laser research with the final commissioning of all 192 beams at the National Ignition Facility (NIF). NIF is a department of energy (DOE) funded project more than 10 years in the making located at the Lawrence Livermore National Laboratory (LLNL). The following research was done as one of many preliminary experiments done to prepare for these historic events. The primary focus of the experimental campaign this paper addresses is to test and develop a thermal x-radiation source using a short pulse laser. This data is hoped to provide information about the thermal transport mechanisms important in the development of prediction models in High Energy Density (HED) science. One of several diagnostics fielded was a soft x-ray imager (SXRI) which is detailed in this paper. The SXRI will be used to measure the relative size of the heated region and also the relative level of specific x-ray emissions among several shot and target configurations. The laser system used was the Titan laser located in the Jupiter Laser Facility (JLF) at Lawrence Livermore National Laboratory (LLNL). Titan uses the JLF Janus Nd:glass laser west frontend system with a Optical Parametric Chirped Pulse Amplification (OPCPA) in place of the nanosecond oscillator. The system is capable of producing laser intensities of over a petawatt with several tens of joules delivered in the beam.

Stafford, D

2009-06-01

126

Optical Design of High-Performance Beam Lines for X-Ray Lithography  

NASA Astrophysics Data System (ADS)

In this paper is presented an optical design of high-performance beam lines for synchrotron-radiation-based X-ray lithography. The optical system is composed of a single toroidal scanning mirror and a movable beryllium window whose motions are synchronized. The use of a toroidal scanning mirror is thought to cause excessive deformation of beam shape during scanning and to suppress the light-condensing capacity. This problem has been solved by placing the rotating center of the mirror near the light source point. Thus, intense illumination power can be obtained. A beam reflected by the toroidal mirror forms an arc-shaped section, which causes nonuniformity in the exposure intensity. A beryllium window foil with a specific curvature can compensate the nonuniformity. A series of analytical studies and computer simulations have proven the performance of the optical design.

Toyota, Eijiro

1999-06-01

127

Inductive energy technology for pulsed intense x-ray sources  

SciTech Connect

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 present generators and power conditioning for future pulsed power IES designs are discussed. Because of the complex physics governing the interaction among the power conditioning, power flow, and load performance, DSWA supports studies of power flow to the load that converts the electromagnetic energy to X-ray radiation. Experiments performed at high power levels and resulting improvements in performance are reported.

Ware, K.D.; Filios, P.G.; Gullickson, R.L.; Rowley, J.E.; Schneider, R.F.; Summa, W.J. [Defense Special Weapons Agency, Alexandria, VA (United States); Vitkovitsky, I.M. [Logicon RDA, Arlington, VA (United States)

1997-04-01

128

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

129

Signal-to-noise ratio of intensity interferometry experiments with highly asymmetric x-ray sources  

SciTech Connect

The authors discuss the signal-to-noise ratio of an intensity interferometry experiment for a highly asymmetric x-ray source using different aperture shapes in front of the photodetectors. It is argued that, under ideal conditions using noiseless detectors and electronics, the use of slit-shaped apertures, whose widths are smaller but whose lengths are much greater than the transverse coherence widths of the beam in the corresponding directions, provides no signal-to-noise advantage over the use of pinhole apertures equal to or smaller than the coherence area. As with pinholes, the signal-to-noise ratio is determined solely by the count degeneracy parameter and the degree of coherence of the beam. This contrasts with the signal-to-noise ratio enhancement achievable using slit-shaped apertures with an asymmetric source in a Young`s experiment.

Feng, Y.P.; McNulty, I.; Xu, Z.; Gluskin, E. [Argonne National Lab., IL (United States). Experimental Facilities Div.

1995-06-23

130

Signal-to-noise ratio of intensity interferometry experiments with highly asymmetric x-ray sources  

SciTech Connect

We discuss the signal-to-noise ratio of an intensity interferometry experiment for a highly asymmetric x-ray source using different aperture shapes in front of the photodetectors. It is argued that, under ideal conditions using noiseless detectors and electronics, the use of slit-shaped apertures, whose widths are smaller but whose lengths are much greater than the transverse coherence widths of the beam in the corresponding directions, provides no signal-to-noise advantage over the use of pinhole apertures equal to or smaller than the coherence area. As with pinholes, the signal-to-noise ratio is determined solely by the count degeneracy parameter and the degree of coherence of the beam. This contrasts with the signal-to-noise ratio enhancement achievable using slit-shaped apertures with an asymmetric source in a Young`s experiment.

Feng, Y.P.; McNulty, I.; Xu, Z.; Gluskin, E.

1997-02-11

131

The energy calibration of x-ray absorption spectra using multiple-beam diffraction  

SciTech Connect

A new method for calibrating the energy scale of x-ray absorption spectra from an energy dispersive spectrometer has been developed. Distinct features in the diffracted intensity of the curved silicon crystal monochromator have been assigned to multiple-beam diffraction. The photon energies of these structures can be calculated if the precise spacing of the diffracting planes and the orientation of the crystal relative to the incident synchrotron radiation are known. The evaluation of Miller indices of operative reflections and the calculation of the corresponding photon energy is presented. The assignment of operative reflexes is simplified if the monochromator crystal can be rotated around the main diffracting vector {bold H}.

Hagelstein, M.; Cunis, S. (Fachhochschule Ostfriesland, Constantiaplatz 4, D-2970 Emden (Germany)); Frahm, R. (Hamburger Synchrotronstrahlungslabor HASYLAB at DESY, Notkestrasse 85, D-2000 Hamburg 52 (Germany)); Rabe, P. (Fachhochschule Ostfriesland, Constantiaplatz 4, D-2970 Emden (Germany))

1992-01-01

132

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

133

Capillary optics and their applications in x-ray microanalysis  

Microsoft Academic Search

Capillary-based x-ray optics can provide a small, intense x-ray beam for x-ray microanalysis, including microbeam x-ray fluorescence (MXRF) and microbeam x-ray diffraction (MXRD). Monolithic polycapillary focusing optics and tapered monocapillary optics represent the current state- of-the-art of the technology. The design and the complete x-ray characterizations of such x-ray optics are discussed in this thesis. The application of monolithic polycapillary

Ning Gao

1997-01-01

134

Flash imaging of fine structures of cellular organelles by contact x-ray microscopy with a high intensity laser plasma x-ray source  

NASA Astrophysics Data System (ADS)

X-ray flash imaging by contact microscopy with a highly intense laser-plasma x-ray source was achieved for the observation of wet biological cells. The exposure time to obtain a single x-ray image was about 600 ps as determined by the pulse duration of the driving laser pulse. The x-ray flash imaging makes it possible to capture an x-ray image of living biological cells without any artificial treatment such as staining, fixation, freezing, and so on. The biological cells were cultivated directly on the surface of the silicon nitride membranes, which are used for the x-ray microscope. Before exposing the cells to x-rays they were observed by a conventional fluorescent microscope as reference, since the fluorescent microscopes can visualize specific organelles stained with fluorescent dye. Comparing the x-ray images with the fluorescent images of the exact same cells, each cellular organelle observed in the x-ray images was identified one by one and actin filaments and mitochondria were clearly identified in the x-ray images.

Kado, Masataka; Ishino, Masahiko; Kishimoto, Maki; Tamotsu, Satoshi; Yasuda, Keiko; Kinjo, Yasuhito; Shinohara, Kunio

2011-09-01

135

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

136

X-ray intensity-hardness correlation and deep IR observations of the anomalous X-ray pulsar 1RXS J170849-400910  

Microsoft Academic Search

We report here on X-ray and IR observations of the Anomalous X-ray Pulsar (AXP) 1RXS J170849-400910. First, we report on new\\u000a XMM-Newton, Swift-XRT and Chandra observations of this AXP, which confirm the intensity–hardness correlation observed in the\\u000a long term X-ray monitoring of this source. These new X-ray observations show that the AXP flux is rising again, and the spectrum\\u000a hardening.

N. Rea; G. L. Israel; T. Oosterbroek; S. Campana; S. Zane; R. Turolla; V. Testa; M. Méndez; L. Stella

2007-01-01

137

Simultaneous rapid X-ray and optical intensity fluctuations from a small part of a flaring active region  

NASA Astrophysics Data System (ADS)

Observations of three short-lived solar soft X-ray spikes which occurred within a flaring active region on October 19, 1980, are presented. The events took place at a site remote from flare activity, which was in abeyance. The most intense spike was accompanied by emissions in the wings of H-alpha and extended to X-ray energies above 34 keV. A possible interpretation which is consistent with the spectral evolution of the X-ray bursts and the relative timing of the H-alpha broadening with respect to the latter is that the energy was transferred from elsewhere in the active region by a neutral ion beam.

Simnett, G. M.; Mouradian, Z.; Martres, M.-J.; Soru-Escaut, I.

1989-10-01

138

X-ray polarizer based on Kumakhov optics  

Microsoft Academic Search

The use of polarized x-ray beams provides drastic reduction of background connected with Compton scattering from the sample under investigation. In conventional x-ray tubes with isotropic distribution of x rays, the intensity of polarized beam after polarizer is very small. We have carried out the experiment with Kumakhov lens and Barcla polarizer to receive intense x-ray polarized beams. X-ray fluorescent

Vladimir P. Petukhov; Svetlana V. Nikitina

1997-01-01

139

Performance Characteristics Of An 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 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

Willem G. J. Langeveld; Craig Brown; Phil. A. Christensen; Cathie Condron; Michael Hernandez; Mike Ingle; William A. Johnson; Roger D. Owen; Randy Ross; Russell G. Schonberg

2011-01-01

140

Thin film X-ray waveguides: ‘Condenser systems’ for experiments with X-ray beams of 0.1 ?m dimension  

Microsoft Academic Search

This report discusses the latest performance data for X-ray waveguides applied in the production of hard X-ray micro-spots. It is possible to compress an X-ray radiation beam in a thin film waveguide in one direction down to the level of about 0.1 ?m, a value which has not been achieved routinely with any other device. A gain factor of about

W. Jark; S. Di Fonzo; G. Soullié; A. Cedola; S. Lagomarsino

1999-01-01

141

Quasitransient regimes of backward Raman amplification of intense x-ray pulses  

SciTech Connect

New powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulses, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can automatically suppress deleterious instabilities of BRA to the thermal noise. The class of 'quasitransient' BRA regimes identified here shows that it may be feasible to observe x-ray BRA within available x-ray facilities.

Malkin, V. M.; Fisch, N. J. [Princeton University, Princeton, New Jersey 08544 (United States)

2009-10-15

142

Quasitransient regimes of backward Raman amplification of intense x-ray pulses  

NASA Astrophysics Data System (ADS)

New powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulses, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can automatically suppress deleterious instabilities of BRA to the thermal noise. The class of “quasitransient” BRA regimes identified here shows that it may be feasible to observe x-ray BRA within available x-ray facilities.

Malkin, V. M.; Fisch, N. J.

2009-10-01

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

X-ray lithography source  

DOEpatents

A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits is disclosed. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and eliminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an excellent moderate-priced X-ray source for lithography. 26 figures.

Piestrup, M.A.; Boyers, D.G.; Pincus, C.

1991-12-31

145

X-ray lithography source  

DOEpatents

A high-intensity, inexpensive X-ray source for X-ray lithography for the production of integrated circuits. Foil stacks are bombarded with a high-energy electron beam of 25 to 250 MeV to produce a flux of soft X-rays of 500 eV to 3 keV. Methods of increasing the total X-ray power and making the cross section of the X-ray beam uniform are described. Methods of obtaining the desired X-ray-beam field size, optimum frequency spectrum and elminating the neutron flux are all described. A method of obtaining a plurality of station operation is also described which makes the process more efficient and economical. The satisfying of these issues makes transition radiation an exellent moderate-priced X-ray source for lithography.

Piestrup, Melvin A. (Woodside, CA); Boyers, David G. (Mountain View, CA); Pincus, Cary (Sunnyvale, CA)

1991-01-01

146

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

147

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

148

New method for measuring beam profiles using a parametric X-ray pinhole camera  

NASA Astrophysics Data System (ADS)

We propose a new method for measuring electron beam profiles using parametric X-ray radiation. In this method, a pinhole is placed between the source of parametric X-ray radiation and a two-dimensional X-ray detector, and the beam profile can be reconstructed on the detector, i.e., based on the principle of a pinhole camera. The profiles are in good agreement with the results obtained using a standard method with optical transition radiation. This method may prove useful to measure profiles of electron beams with short bunch lengths in recent advanced linear accelerators.

Takabayashi, Y.; Sumitani, K.

2013-11-01

149

Beam-induced damage on diffractive hard X-ray optics.  

PubMed

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. PMID:20975225

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

2010-09-02

150

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

151

The fabrication of x-ray masks using proton beam writing  

NASA Astrophysics Data System (ADS)

We have developed a simplified method of fabricating x-ray masks for deep x-ray lithography by using proton beam writing (PBW) without subsequent soft x-ray copying steps. Combining direct PBW and subsequent electroplating, x-ray masks with gold absorber patterns of up to 11 µm height and with vertical and smooth sidewalls were fabricated. The smallest size in the absorber pattern is less than 0.5 µm in this work. The masks were used for x-ray lithography with synchrotron radiation, and 870 µm SU-8 structures with smooth sidewalls were produced. This fabrication method is promising to be an important alternative to conventional methods for x-ray mask making.

Yue, Weisheng; Chiam, Sher-Yi; Ren, Yaping; Anton van Kan, Jeroen; Osipowicz, Thomas; Jian, Linke; Moser, Herbert O.; Watt, Frank

2008-08-01

152

Whitebeam X-ray topography  

Microsoft Academic Search

After radiography, white-beam X-ray topography (XRT) is the simplest X-ray imaging technique for crystals. An X-ray topograph is formed by a Bragg reflexion and is in effect a high-spatial-resolution Laue ‘spot’. Synchrotron radiation has given XRT additional powers, with its broad continuous spectrum, small beam divergence, high intensity, strong polarization and regular pulsed time structure. Each Laue image, however, may

Moreton Moore

2012-01-01

153

X-ray beam splitting design for concurrent imaging at hard X-ray FELs and synchrotron facilities  

NASA Astrophysics Data System (ADS)

A new configuration of diffractive–refractive optics for beam splitting is investigated. The set-up can be applied to perform imaging with two beams simultaneously. It brings advantages toward dynamic studies using image guided diffraction or fluorescence spectroscopy. The optimal energy range of operation for the beam-splitter is between 7 keV and 24 keV, reaching best efficiency at an energy of 10 keV. Due to the long focusing distances (several tens of meters) created by the diffractive–refractive optics and the higher refraction efficiency in the softer energy range, the presented set-ups are ideal for hard X-ray FEL sources.

Oberta, P.; Mokso, R.

2013-11-01

154

Measurements of relative x-ray line intensities and their application to a single standard procedure for quantitative x-ray microanalysis  

SciTech Connect

X-ray spectra collected by an energy dispersive spectrometer on an electron microprobe analyzer were deconvoluted to determine relative line intensities between elements for a wide range of atomic numbers. The relative line intensities within spectral series for K, L, and M lines were also obtained. In the case of K{alpha} lines an empirical formula is proposed for the prediction of generated line intensities of pure element standards relative to that of Cu K{alpha} at 20 keV used as a reference standard, although other line references can be used for lower beam energies. The generated ratios can be predicted with accuracy generally better than 2% relative to the actual measured values. The relationship covers elements with atomic numbers in the range of 12 (Mg) to 32 (Ge) and incident beam energies between 5 and 20 keV. Unfortunately, L and M line data could not be fitted with the same level of accuracy to a single expression due to the inherent scatter in the data as a function of atomic number. These data are therefore presented in tabular form. The availability of relative line intensity measurements as a function of atomic number makes it possible to perform accurate quantitative x-ray microanalysis with the measurement of a single standard rather than a separate measurement of each element standard. As a result not only are measurement times shorter, but it is also possible to estimate values for elements for which pure standards may not be available. Furthermore, the method has been extended to quantitative analysis based only on the measurement of the sample spectrum.

Hatzistergos, M. S.; Lifshin, E. [College of Nanoscale Science and Engineering, University at Albany, 251 Fuller Road, Albany, New York 12203 (United States)

2006-12-15

155

X-ray intensity, ozone density, and VLF wave intensity observed by scientific balloon experiments at Esrange  

Microsoft Academic Search

The first Japanese scientific balloon experiment at Esrange, Kiruna, Sweden was carried out on September 10 and 11, 1980, in order to obtain vertical profiles of X-ray intensity, ozone density, and VLF wave spectrum intensity at a northern high-latitude. Since there were very quiet geomagnetic conditions for two balloon flights, observational results reveal a typical quiet time X-ray intensity profile

M. Ejiri; M. Ayukawa; H. Yamagishi; T. Ono; T. Hirasawa; T. Kamada; M. Kodama; Y. Hirasima; T. Ogawa; N. Iwagami

1982-01-01

156

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, Rui

2011-03-21

157

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

158

Strain field and scattered intensity profiling with energy dispersive x-ray scattering  

Microsoft Academic Search

Two powerful synchrotron x-ray scattering techniques for residual strain depth-profiling and tomography-like scatter-intensity profiling of materials are presented. The techniques utilize energy dispersive x-ray scattering, from a fixed microvolume, with microscanning of the specimen being used to profile its interior. The tomography-like profiles exploit scattering-cross-section variations, and can be contrast enhanced by separately monitoring scattering from different crystal structures. The

M. Croft; I. Zakharchenko; Z. Zhong; Y. Gurlak; J. Hastings; J. Hu; R. Holtz; M. Dasilva; T. Tsakalakos

2002-01-01

159

Lensless Diffractive Imaging Using Tabletop Coherent High-Harmonic Soft-X-Ray Beams  

SciTech Connect

We present the first experimental demonstration of lensless diffractive imaging using coherent soft x rays generated by a tabletop soft-x-ray source. A 29 nm high harmonic beam illuminates an object, and the subsequent diffraction is collected on an x-ray CCD camera. High dynamic range diffraction patterns are obtained by taking multiple exposures while blocking small-angle diffraction using beam blocks of varying size. These patterns reconstruct to images with 214 nm resolution. This work demonstrates a practical tabletop lensless microscope that promises to find applications in materials science, nanoscience, and biology.

Sandberg, Richard L.; Paul, Ariel; Raymondson, Daisy A.; Haedrich, Steffen; Gaudiosi, David M.; Holtsnider, Jim; Tobey, Ra'anan I.; Cohen, Oren; Murnane, Margaret M.; Kapteyn, Henry C.; Song, Changyong; Miao Jianwei; Liu Yanwei; Salmassi, Farhad [JILA and Department of Physics, University of Colorado and NSF Engineering Research Center in Extreme Ultraviolet Science and Technology, Boulder, Colorado 80309 (United States); Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Center for X-Ray Optics, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2007-08-31

160

Correction of scattered radiation for cone-beam computed tomography at high X-ray energies  

Microsoft Academic Search

Cone-beam computed tomography (CT) using X-ray tubes of high energy (450 keV) faces the problem of strong artifacts and a significant contrast degradation in reconstructed images. System components of cone-beam CT scanners operating at high X-ray energies have to be optimized to reduce the amount of scattered photons hitting the detector. In addition it is mandatory to apply scatter correction

Alexander Flisch; Alice Miceli; Raphael Thierry; Jilrgen Hofmann

2008-01-01

161

Ultra fast electron beam X-ray tomography and its application to multiphase flow measurement  

Microsoft Academic Search

An ultra fast electron beam CT scanner is introduced which has been developed for flow measurement applications. Its basic design comprises an electron gun with beam optics and fast electromagnetic deflection system and an ultra fast X-ray detector based on room-temperature semiconductor converters. As in other tomographic imaging modalities radiographic projections are generated by a moving X-ray source, in this

Uwe Hampel; Frank Fischer

2008-01-01

162

Single-component chemically amplified resist materials for electron-beam and x-ray lithography  

Microsoft Academic Search

Copolymers of 4-tert-butoxycarbonyloxystyrene (TBS) and sulfur dioxide (SO2) have been found to act as sensitive x-ray ((lambda) equals 14 angstrom) and moderately sensitive electron-beam, single component, chemically amplified, aqueous base soluble positive acting resists. The x-ray and electron-beam response of these materials was a function of copolymer composition, where an increase in the sulfur dioxide content enhanced the resist sensitivity.

Anthony E. Novembre; Woon W. Tai; Janet M. Kometani; James E. Hanson; Omkaram Nalamasu; Gary N. Taylor; Elsa Reichmanis; Larry F. Thompson

1991-01-01

163

Simulations of Bragg diffraction of a focused x-ray beam by a single crystal with an epitaxial layer  

SciTech Connect

The Bragg case diffraction of a narrow x-ray beam in a multilayer crystal is studied theoretically. The beam produced by a parabolic refractive lens is Bragg reflected by a crystalline sample and a spatial distribution of the intensity is recorded by a detector placed at the focus of the lens. This x-ray optical scheme represents a topographic technique which is extremely sensitive to a depth variation of a crystalline structure. Simulations of the intensity pattern were performed by using a computational technique based on a convolution of individual propagators by performing a double fast Fourier transform procedure. It was shown that each interface in a multilayer crystal can be observed on the intensity pattern with a contrast depending on the incident angle. Thus, by recording a series of images at different angles, valuable depth sensitive structural information can be obtained.

Kohn, V. G. [Russian Research Center 'Kurchatov Institute', 123182, Moscow (Russian Federation); Kazimirov, A. [Cornell High Energy Synchrotron Source, Cornell University, Ithaca, New York 14853 (United States)

2007-06-01

164

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 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. [Rapiscan Laboratories, Inc., Sunnyvale, CA 94085 (United States); Johnson, William A.; Owen, Roger D. [HESCO/PTSE Inc., Alameda, CA 94501 (United States); Schonberg, Russell G. [Schonberg Research Corporation, Los Altos, CA 94023 (United States)

2009-03-10

165

The Use of Coherent X-Ray Beams to Study the Dynamics of Soft Condensed Matter Systems  

NASA Astrophysics Data System (ADS)

The study of slow dynamics in soft condensed matter systems has been of interest for many years. One of the most powerful techniques for studying dynamics at these time scales has been Dynamical Light Scattering (DLS). However, it was recognized over twenty years ago that a similar application of X-rays in order to achieve shorter length scales and avoid problems of multiple and stray particle scattering, could open up whole new areas of research. The advent of the high-brilliance third generation synchrotron X-ray sources over a decade ago made it possible for the first time to deliver an intense beam of highly coherent X-rays, enabling many new applications of X-ray scattering, some of which will be discussed. In particular, the technique of X-ray Photon Correlation Spectroscopy (XPCS), the X-ray analog of DLS, has now become an exciting new research area with applications primarily in soft condensed matter. In this talk, we shall trace the development of the use of coherent X-ray beams from the early demonstrations at the NSLS, ESRF and APS synchrotron light sources to current applications which include the study of dynamical fluctuations in colloids and polymers and in particular the study of surface fluctuations in liquid films and membranes. We shall show how XPCS has yielded interesting new results on these systems difficult if not impossible to obtain by other techniques. I wish to acknowledge collaborations with Hyunjung Kim, Larry Lurio, Zhang Jiang, Christian Gutt, Metin Tolan, Tuana Ghaderi, Jyotsana Lal, Simon Mochrie, Miriam Rafailovich, Jonathan Sokolov, Chinhua Li, Tadanori Koga, Xuesong Jiao, Suresh Narayanan.

Sinha, Sunil

2007-03-01

166

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

167

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

168

A Diffraction System with an X-ray Beam of a Band of Wavelengths  

SciTech Connect

New diffraction system has been constructed at the Synchrotron Radiation Center at Ritsumeikan University, in which a parallel X-ray beam of a band of wavelengths is produced by reflection from a multilayer monochromator of depth-graded thicknesses. The band width is 0.013 nm and the useful wavelength range is from 0.16 nm to 0.20 nm. Diffraction patterns were taken from a single crystal of an enantiomorphous ferrocene-derivative compound employing an Imaging Plate as a detector. Bragg reflections are seen elongated with a characteristic intensity profile due to anomalous dispersion. Bijvoet pair of reflections show a clear difference in the profile on the short wavelength side of the absorption edge and distinction between the enantiomers can be made more easily than the classical method based on the comparison of integrated intensities.

Koganezawa, T.; Iwasaki, H.; Yoshimura, Y.; Nakamura, N. [Faculty of Science and Engineering, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan); Shoji, T. [X-ray Research Laboratory, RIGAKU Coorporation, Takatsuki, Osaka 569-1146 (Japan)

2004-05-12

169

Determination of multiwavelength anomalous diffraction coefficients at high x-ray intensity  

NASA Astrophysics Data System (ADS)

The high-intensity version of multiwavelength anomalous diffraction (MAD) has a potential for solving the phase problem in femtosecond crystallography with x-ray free-electron lasers (XFELs). For MAD phasing, it is required to calculate or measure the MAD coefficients involved in the key equation, which depend on XFEL pulse parameters. In this work, we revisit the generalized Karle-Hendrickson equation to clarify the importance of configurational fluctuations of heavy atoms induced by intense x-ray pulses, and investigate the high-intensity cases of transmission and fluorescence measurements of samples containing heavy atoms. Based on transmission/fluorescence and diffraction experiments with crystalline samples of known structures, we propose an experimental procedure to determine all MAD coefficients at high x-ray intensity, which can be used in ab initio phasing for unknown structures.

Son, Sang-Kil; Chapman, Henry N.; Santra, Robin

2013-08-01

170

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

171

Recover the phases from intensity data of x-ray diffraction  

NASA Astrophysics Data System (ADS)

For many years, people believed that in conventional x-ray crystallography one can only record the scattering intensities but not the phases. In order to study structures at the atomic scale, one has to use multibeam measurement or to rely on additional knowledge such as bonding length and to fit the intensity data by trial structure models. In this letter, however, we show that the phases are in fact hidden in the intensity data and can be recovered by studying the peak shoulders. To demonstrate, the x-ray diffraction data of aluminum powder were used to recover the phases and to reconstruct the electron density map.

Xu, Gu

1998-08-01

172

Focusing coherent soft-x-ray radiation to a micrometer spot size with an intensity of 10^14 W\\/cm2  

Microsoft Academic Search

We investigate the focusability of intense coherent soft-x-ray radiation generated by high-order harmonic conversion. The 27th-harmonic wave at 29.6 nm is focused by an off-axis parabolic mirror with a SiC\\/Mg multilayer coating. Focal-spot images are observed from the visible fluorescence induced by the soft-x-ray photons on a Ce:YAG scintillator. We demonstrate focusing of the soft-x-ray beam to a 1-µm spot

Hiroki Mashiko; Akira Suda; Katsumi Midorikawa

2004-01-01

173

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

174

Image reconstruction from an in-line X-ray hologram with intensity distribution constraint  

Microsoft Academic Search

An image reconstruction method for in-line soft X-ray holography is presented. The image is reconstructed by a Fresnel phase-retrieval algorithm using a constraint on the intensity distribution. Experimental results show that the introduction of the intensity constraint is effective for eliminating artifacts such as a twin-image.

Iwao Kodama; Masahiro Yamaguchi; Nagaaki Ohyama; Toshio Honda; Kunio Shinohara; Atsushi Ito; Tatsuya Matsumura; Katsuyuki Kinoshita; Keiji Yada

1996-01-01

175

X-ray scattering intensities of water at extreme pressure and temperature  

SciTech Connect

We have calculated the coherent x-ray scattering intensity of several phases of water at 1500 and 2000 K under high pressure, using ab initio Density Functional Theory (DFT). Our calculations span the molecular liquid, ice VII, and superionic solid phases, including the recently predicted symmetrically hydrogen bonded region of the superionic phase. We show that wide angle x-ray scattering intensity could be used to determine phase boundaries between these high pressure phases, and we compare the results for ice VII and superionic water. We compute simulated spectra and provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We show that our modifed atomic form factors allow for a nearly exact comaprison to the total x-ray scattering intensities calculated from DFT. Finally, we analyze the effect our new form factors have on determination of the oxygen-oxygen radial distribution function.

Goldman, N; Fried, L E

2007-01-03

176

An indirect method of X-ray spectra measurement by simultaneous attenuations of the scattered beam  

NASA Astrophysics Data System (ADS)

Direct and indirect methods of X-ray spectra determination present obstacles to their practical use since they must position either the collimator-detector assembly or the attenuators-ionization chamber, respectively, along the X-ray beam direction. These arrangements require considerable space and in many instances the detectors promptly saturate. An indirect procedure, which overcomes the aforementioned problems, is developed. It consists of the scattering of the X-ray beam from a carbon disk, which is detected simultaneously by several detectors placed away from the beam. The X-ray flux reaching each of these detectors is attenuated in metal sheets of different thicknesses, thus obtaining simultaneously the attenuation curve values. A set of analytical equations are derived to calculate attenuation curves by taking into account all the absorption and elastic and inelastic scattering processes that a beam of photons undergoes when going from the X-ray tube to the detector. Users, even those who are not well acquainted with computer programming, can easily obtain the X-ray spectrum by a least square fitting of a measured attenuation curve to a previously derived analytical expression. A simulated Monte Carlo program of photon transport from the X-ray tube to the detector provided simulated attenuation curves data. Analytically calculated and simulated attenuation curves for the same input spectrum wholly overlap and furthermore, reconstructed spectra from both sets of curves for different kilovoltages are also in full agreement. Finally, in addition to the importance of having the detectors out of the beam direction, the proposed arrangement features other main advantages, namely, only one X-ray tube shot is needed to obtain the required data, the physical processes involved are very well known, analytical equations are easily interpreted, and the measuring apparatuses can be comparatively simple to assemble and operate.

Mainardi, Raúl T.; Bonzi, Edgardo V.

2008-05-01

177

Automatic steering of x-ray beams from NSLS insertion devices using closed orbit feedback  

SciTech Connect

By the middle of this year (1989); there will be five insertion devices installed in the NSLS x-ray electron storage ring. X-ray beams from these devices will be stabilized by local automatic steering systems to reduce beam motion at the end of the beamline. Both the position of the source and the direction of the radiation will be controlled using beam position feedback to the closed orbit. Another system will be installed to stabilize the electron orbit for the LEGS Compton backscattering experiment. Each feedback system will employ at least one x-ray beam position detector; some will also utilize rf electron beam positron monitors. Analog hardware with a digital interface has been designed and will be installed in the near future. A totally digital realization of the feedback controller is under consideration. 6 refs., 6 figs.

Nawrocky, R.J.; Galayda, J.; Klein, J.D.; Singh, O.; Yu, L.H.

1989-01-01

178

Performance Characteristics Of An 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 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; Christensen, Phil. A.; Condron, Cathie; Hernandez, Michael; Ingle, Mike; Johnson, William A.; Owen, Roger D.; Ross, Randy; Schonberg, Russell G.

2011-06-01

179

X ray laser  

NASA Astrophysics Data System (ADS)

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

Nilsen, J.

1991-10-01

180

X-ray laser  

DOEpatents

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

Nilsen, J.

1991-10-12

181

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

182

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

183

Effect of high-intensity x-ray radiation on Bragg diffraction in silicon and diamond  

SciTech Connect

We simulated the Bragg reflection of high-intensity short x-ray pulses from single-crystal silicon and diamond by coupling tight-binding-molecular dynamics with a simple atomic kinetics model. We found that even when the pulse-averaged Bragg intensity degrades significantly, the reflectivity drops only slightly at the beginning of the pulse until the lattice is disordered by non-thermal melting. These results suggest that Bragg reflectors could produce shortened x-ray pulses through temporal slicing.

Hau-Riege, Stefan P.; Pardini, Tommaso [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-12-01

184

Production of a keV X-Ray Beam from Synchrotron Radiation in Relativistic Laser-Plasma Interaction  

Microsoft Academic Search

We demonstrate that a beam of x-ray radiation can be generated by simply focusing a single high-intensity laser pulse into a gas jet. A millimeter-scale laser-produced plasma creates, accelerates, and wiggles an ultrashort and relativistic electron bunch. As they propagate in the ion channel produced in the wake of the laser pulse, the accelerated electrons undergo betatron oscillations, generating a

Antoine Rousse; Kim Ta Phuoc; Rahul Shah; Alexander Pukhov; Eric Lefebvre; Victor Malka; Sergey Kiselev; Fréderic Burgy; Jean-Philippe Rousseau; Donald P. Umstadter; Daniéle Hulin

2004-01-01

185

Ultra fast electron beam X-ray computed tomography for two-phase flow measurement  

Microsoft Academic Search

Electron beam X-ray CT is a new technique for a fast measurement of multiphase flows with frame rates of 1000 images per second and more. It gives, in principle, quantitatively accurate images of the flow at high spatial resolution and it is non-intrusive since moderately radiation absorbing vessel walls can be penetrated by X-rays. However, on the road to a

F. Fischer; U. Hampel

2010-01-01

186

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

187

Hard X-ray multilayer coated astronomical mirrors by e-beam deposition  

Microsoft Academic Search

A number of X-ray astronomical missions of near future (Constellation-X, XEUS, Simbol-X) will make use of hard X-rays (10-100 keV) optics with broad-band multilayer coatings. A possible technique under development is based on an extension of the already tested replication of a coated mandrel by e-beam deposition and nickel electroforming already successfully used for the soft (0.1 - 10 keV)

Daniele Spiga; Giovanni Pareschi; Gabriele Grisoni; Giuseppe Valsecchi

2004-01-01

188

Ion beam figuring of nickel mandrels for x-ray replication optics  

Microsoft Academic Search

The x-ray telescopes foreseen for future x-ray missions will need an high number of mirrors. Using for their production the replication method, an high number of mandrels will be necessary. A cost-effective approach that offers accurate control of the mandrels shape is the ion beam figuring. Using this procedure the aluminum-kanigen mandrels are initially optically figured by diamond turning or

Mauro Ghigo; Oberto Citterio; Paolo Conconi; Franco Mazzoleni

2001-01-01

189

Phase retrieval with two-beam off-axis x-ray holography  

Microsoft Academic Search

A wave front dividing x-ray interferometer with a prism was applied to two-beam off-axis holography. Complex amplitudes at the detector plane, which were derived from the hologram using the fringe scanning method, were inversely transformed to those at the exit surface of the specimen. The x-ray phase shift due to the amorphous carbon particles was quantitatively determined with the background

Yoshiki Kohmura; Tatsuyuki Sakurai; Tetsuya Ishikawa; Yoshio Suzuki

2004-01-01

190

Electron-beam lithography of optical elements for x-ray range (Poster Paper)  

Microsoft Academic Search

Experimental investigations and special software for the e-beam exposure system gives the possibility of decreasing the influence of proximity effects and field distortion. The results of creating a focusing element for the soft x-ray range are described: amplitude and phase- contrast Fresnel zone plates as well as reflected Bragg-Fresnel lenses on the base of multilayer x-ray mirrors.

Sergey V. Babin; Alexei I. Erko

1992-01-01

191

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

192

Superficial dosimetry imaging based on C?erenkov emission for external beam radiotherapy with megavoltage x-ray beam.  

PubMed

Purpose: C?erenkov radiation emission occurs in all tissue, when charged particles (either primary or secondary) travel at velocity above the threshold for the C?erenkov effect (about 220 KeV in tissue for electrons). This study presents the first examination of optical C?erenkov emission as a surrogate for the absorbed superficial dose for MV x-ray beams.Methods: In this study, Monte Carlo simulations of flat and curved surfaces were studied to analyze the energy spectra of charged particles produced in different regions near the surfaces when irradiated by MV x-ray beams. C?erenkov emission intensity and radiation dose were directly simulated in voxelized flat and cylindrical phantoms. The sampling region of superficial dosimetry based on C?erenkov radiation was simulated in layered skin models. Angular distributions of optical emission from the surfaces were investigated. Tissue mimicking phantoms with flat and curved surfaces were imaged with a time domain gating system. The beam field sizes (50 × 50-200 × 200 mm(2)), incident angles (0°-70°) and imaging regions were all varied.Results: The entrance or exit region of the tissue has nearly homogeneous energy spectra across the beam, such that their C?erenkov emission is proportional to dose. Directly simulated local intensity of C?erenkov and radiation dose in voxelized flat and cylindrical phantoms further validate that this signal is proportional to radiation dose with absolute average discrepancy within 2%, and the largest within 5% typically at the beam edges. The effective sampling depth could be tuned from near 0 up to 6 mm by spectral filtering. The angular profiles near the theoretical Lambertian emission distribution for a perfect diffusive medium, suggesting that angular correction of C?erenkov images may not be required even for curved surface. The acquisition speed and signal to noise ratio of the time domain gating system were investigated for different acquisition procedures, and the results show there is good potential for real-time superficial dose monitoring. Dose imaging under normal ambient room lighting was validated, using gated detection and a breast phantom.Conclusions: This study indicates that C?erenkov emission imaging might provide a valuable way to superficial dosimetry imaging in real time for external beam radiotherapy with megavoltage x-ray beams. PMID:24089916

Zhang, Rongxiao; Glaser, Adam K; Gladstone, David J; Fox, Colleen J; Pogue, Brian W

2013-10-01

193

High intensity x-ray line emission from aluminum plasmas generated by a 120 TW, 30 fs laser pulse  

SciTech Connect

The K-shell x-ray spectra from the aluminum plasmas generated by the interaction of the 120 TW, 30 fs laser with aluminum targets have been measured by defocusing the laser beam. Laser energy-normalized intensity of the He-a line increases with the laser intensity approximately as a power law {epsilon}{proportional_to}I{sub L}{sup {gamma}} with the much smaller exponent of {gamma}=0.062 compared to {gamma}=0.2{approx}0.5 in the previous experiments, which is caused by the stronger radial thermal diffusivity in the target for the smaller laser spot. Laser-to-He-a line conversion efficiency of up to 1.9x10{sup -3} and as high as about 3x10{sup 13} photons/2{pi} Sr aluminum He-a line x-ray source have been achieved for a single shot due to the preplasma effect and relatively large laser spot and energy for the single shot. The x-ray spectra as a function of the laser intensity are also analyzed to get the electron temperature and density.

Yang Jiamin; Zhang Jiyan; Yang Guohong; Zhang Baohan [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China); National Key Laboratory of High Temperature and Density Plasmas, Mianyang 621900 (China); Hu Zhimin; Zhu Tuo; Zhao Yang; Wen Tianshu; Wang Zhebin; Ding Yaonan; Wei Mingxi [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)

2008-11-15

194

An investigation of dose changes for therapeutic kilovoltage x-ray beams with underlying lead shielding  

SciTech Connect

Kilovoltage x-ray beams are used to treat cancer on or close to the skin surface. Many clinical cases use high atomic number materials as shielding to reduce dose to underlying healthy tissues. In this work, we have investigated the effect on both the surface dose and depth doses in a water phantom with lead shielding at depth in the phantom. The EGSnrc Monte Carlo code was used to simulate the water phantom and to calculate the surface doses and depth doses using primary x-ray beam spectra derived from an analytical model. The x-ray beams were in the energy range of 75-135 kVp with field sizes of 2, 5 and 8 cm diameter. The lead sheet was located beneath the water surface at depths ranging from 0.5-7.5 cm. The surface dose decreased as the lead was positioned closer to the water surface and as the field size was increased. The variation in surface dose as a function of x-ray beam energy was only small but the maximum reduction occurred for the 100 kVp x-ray beam. For the 8 cm diameter field with the lead at 1 cm depth and using the 100 kVp x-ray beam, the surface dose was reduced to 0.898 of the surface dose in the water phantom only. Measured surface dose changes, using a Farmer-type ionization chamber, agreed with the Monte Carlo calculated doses. Calculated depth doses in water with a lead sheet positioned below the surface showed that the dose fall-off increased as the lead was positioned closer to the water surface as compared to the depth dose in the water phantom only. Monte Carlo calculations of the total x-ray beam spectrum at the water surface showed that the total fluence decreased due to a reduction in backscatter from within the water and very little backscatter from the lead. The mean energy of the x-ray spectrum varied less than 1 keV, with the lead at 1 cm beneath the water phantom surface. As the Monte Carlo calculations showed good agreement with the measured results, this method can be used to verify surface dose changes in clinical situations where measurements are difficult. The clinical impact of the use of lead must be considered in the dose prescription for patients being treated with kilovoltage x-ray beams.

Hill, Robin; Healy, Brendan; Holloway, Lois; Baldock, Clive [Institute of Medical Physics, School of Physics, University of Sydney, Australia and Department of Radiation Oncology, Royal Prince Alfred Hospital, Sydney (Australia); Peter MacCallum Cancer Institute, Melbourne, Victoria (Australia); Cancer Therapy Centre, Liverpool Hospital, Sydney, Australia and Institute of Medical Physics, School of Physics, University of Sydney (Australia); Institute of Medical Physics, School of Physics, University of Sydney (Australia)

2007-07-15

195

An investigation of dose changes for therapeutic kilovoltage X-ray beams with underlying lead shielding.  

PubMed

Kilovoltage x-ray beams are used to treat cancer on or close to the skin surface. Many clinical cases use high atomic number materials as shielding to reduce dose to underlying healthy tissues. In this work, we have investigated the effect on both the surface dose and depth doses in a water phantom with lead shielding at depth in the phantom. The EGSnrc Monte Carlo code was used to simulate the water phantom and to calculate the surface doses and depth doses using primary x-ray beam spectra derived from an analytical model. The x-ray beams were in the energy range of 75-135 kVp with field sizes of 2, 5 and 8 cm diameter. The lead sheet was located beneath the water surface at depths ranging from 0.5-7.5 cm. The surface dose decreased as the lead was positioned closer to the water surface and as the field size was increased. The variation in surface dose as a function of x-ray beam energy was only small but the maximum reduction occurred for the 100 kVp x-ray beam. For the 8 cm diameter field with the lead at 1 cm depth and using the 100 kVp x-ray beam, the surface dose was reduced to 0.898 of the surface dose in the water phantom only. Measured surface dose changes, using a Farmer-type ionization chamber, agreed with the Monte Carlo calculated doses. Calculated depth doses in water with a lead sheet positioned below the surface showed that the dose fall-off increased as the lead was positioned closer to the water surface as compared to the depth dose in the water phantom only. Monte Carlo calculations of the total x-ray beam spectrum at the water surface showed that the total fluence decreased due to a reduction in backscatter from within the water and very little backscatter from the lead. The mean energy of the x-ray spectrum varied less than 1 keV, with the lead at 1 cm beneath the water phantom surface. As the Monte Carlo calculations showed good agreement with the measured results, this method can be used to verify surface dose changes in clinical situations where measurements are difficult. The clinical impact of the use of lead must be considered in the dose prescription for patients being treated with kilovoltage x-ray beams. PMID:17822012

Hill, Robin; Healy, Brendan; Holloway, Lois; Baldock, Clive

2007-07-01

196

Characterisation of microfocused beam for synchrotron powder diffraction using a new X-ray camera  

Microsoft Academic Search

The powder diffraction beamline I11, Diamond Light Source, is being continually upgraded as requirements of the user community evolve. Intensities of X-rays from the I11 in-vacuum electron undulator in the 3 GeV synchrotron fall off at higher energies. By focusing higher energy X-rays, we can overcome flux limitations, and open up new diffraction experiments. Here, we describe characterisation of microfocusing

C Thomas; J Potter; C C Tang; A R Lennie

2012-01-01

197

Effects of beam-tube roughness on x-ray free electron laser performance  

Microsoft Academic Search

In an x-ray free electron laser like the Linear Coherent Light Source being designed at SLAC, electron bunches about 70mum FWHM long are sent into a beam tube only 5 mm in internal diameter and more than 100 m in length. Because of the surface roughness of the beam tube, wakefields can be generated that catch up to the bunch

Gennady Stupakov; Ruth Ellen Thomson; Dieter Walz; Roger Carr

1999-01-01

198

Low energy ion beam monitoring system by dosimetry film and particle induced X-ray  

Microsoft Academic Search

A simple monitoring system for a low energy (less than 5 MeV) proton beam by dosimetry film was developed. A few mum thick Ni foil was installed in front of the film to produce X-rays which develop the film. To eliminate heat damage by the ion beam, a Ni foil was prepared on a 500 mum thick graphite sheet which

H. W. Choi; H. J. Woo; J. H. Park; G. H. Lee; G. D. Kim; J. K. Kim; W. Hong; C. H. Eum

2007-01-01

199

Ion Beam Pulse Compression by Its Conversion into Soft X-Ray  

NASA Astrophysics Data System (ADS)

A new method to compress ion beam pulse is proposed, where ion beam of 1013 W/cm2 at 100 ns is converted into a focusable X-ray of 1014 W/cm2 at ˜ 10 ns. The method could be used for an energy focusing into a small volume and used in LIB (Light Ion Beam), HIB (Heavy Ion Beam) and even in KrF laser.

Yabe, Takashi

1984-01-01

200

Pionic x-ray intensities from C, CH2 and CD2  

NASA Astrophysics Data System (ADS)

The relative intensities of the carbon L? and L? pionic X-ray lines from graphite, polythylene, and deuterated polyethylene have been measured. No differences between CH2 and CD2 were observed, but differences were found between graphite and the two polyethylene targets.

Daniel, H.; Hutson, R. L.; Leon, M.; Schillaci, M. E.; Seki, R.

1980-01-01

201

X-rays from high-intensity, short-pulse laser interaction with solids  

NASA Astrophysics Data System (ADS)

Laser pulses with high intensity (up to 1018 W/cm2) and short duration (100 fs) were focused on solids. The result was highly ionized material and hot electrons, along with the emission of short pulse x-rays and unicycle electromagnetic pulses with subpicosecond duration.

Falcone, R. W.; Gordon, S. P.; Hamster, H.; Sullivan, A.

1993-10-01

202

Quasitransient regimes of backward Raman amplification of intense x-ray pulses  

NASA Astrophysics Data System (ADS)

The backward Raman amplification (BRA) of laser pulses is considered under conditions when important features of the transient BRA survive, while BRA is noticeably affected by damping of the Langmuir wave mediating energy transfer from the pump to the pumped pulse. These quasitransient BRA regimes appear to be relevant to possible principle-of-proof experiments on BRA of intense x-ray laser pulses in plasmas. In particular, such experiments found to be feasible within the parameter range of currently built powerful soft x-ray sources.

Malkin, Vladimir; Fisch, Nathaniel

2008-11-01

203

Absorption and x-ray measurements from ultra-intense laser-plasma interactions  

NASA Astrophysics Data System (ADS)

The interaction of subpicosecond 1.06 micrometers laser light at intensities up to 1018 W/cm2 with dense preformed plasmas is investigated by measurements of the absorption of the laser light in the plasma and by measurements of the production of bremsstrahlung x- rays. Absorption measurements are made by collecting the scattered light in an Ulbricht sphere. Light scattered in the backward and specular directions is collected separately. Measurements are presented for both high and low Z targets. X-ray production is measured using a nine channel filter/scintillator spectrometer.

Klem, Daniel E.; Darrow, Christopher B.; Lane, Stephen M.; Perry, Michael D.

1993-07-01

204

Absorption and x-ray measurements from ultra-intense laser-plasma interactions  

SciTech Connect

The interaction of subpicosecond 1.06 mm laser light at intensities up to 10{sup 18} W/cm{sup 2} with dense performed plasmas is investigated by measurements of the absorption of the laser light in the plasma and by measurements of the production of bremsstrahlung x-rays. Absorption measurements are made by collecting the scattered light in an Ulbricht sphere. Light scattered in the backward and specular directions is collected separately. Measurements are presented for both high and low Z targets. X-ray production is measured using a nine channel filter/scintillator spectrometer.

Klem, D.E.; Darrow, C.; Lane, S.; Perry, M.D.

1993-03-01

205

Studies of electron beams and X-Rays within different plasma-focus devices  

NASA Astrophysics Data System (ADS)

The paper presents a summary of investigations, which were performed with two mediumsize Plasma-Focus (PF) facilities, operated at IPJ in Swierk, Poland, during the recent few years. Attention is paid to experiments performed with MAJA-PF and PF-360 devices. which were run within the energy range from 37 kJ to 170 kJ. To analyze the emitted electron beams (e-beams) and X-rays, the use was made of different time-integrated and time-resolved diagnostic techniques, e.g. Cerenkov detectors, magnetic analyzers, vacuum X-ray pinhole cameras and scintillation detectors. A qualitative and quantitative analysis of the obtained results has been performed. The correlation of relativistic e-beams and X-ray pulses with other PF phenomena has also been discussed.

Zebrowski, J.; Sadowski, M. J.; Jakubowski, L.

2004-03-01

206

Expanded beam x-ray optics calibration facility at the Daresbury Synchrotron  

NASA Astrophysics Data System (ADS)

A facility for the calibration of X-ray Space Instrumentation has been established for the Daresbury Synchrotron. The facility provides a continuously tunable beam with (Delta) (lambda) /(lambda) X-rays, approximately 200 mm wide, obtained from an extremely asymmetric reflection in large perfect crystals of Si. The beam is collimated to < 20 arcsec. Data from tests using large (approximately 250 mm long) beam expander crystals in the energy range from 6 - 12 kev are presented. The planned calibration of the two X-ray telescopes (XSPECT/SODART and JET-X) will be described.

Christensen, Finn E.; Hornstrup, Allan; Frederiksen, P. K.; Abdali, Salim; Grundsoe, P.; Schnopper, Herbert W.; Lewis, R. A.; Hall, C. H.; Borozdin, K. N.

1994-02-01

207

Comparison of intensity modulated x-ray therapy and intensity modulated proton therapy for selective subvolume boosting: a phantom study  

NASA Astrophysics Data System (ADS)

Selective subvolume boosting can theoretically improve tumour control probability while maintaining normal tissue complication probabilities similar to those of uniform dose distributions. In this work the abilities of intensity-modulated x-ray therapy (IMXT) and intensity-modulated proton therapy (IMPT) to deliver boosts to multiple subvolumes of varying size and proximities are compared in a thorough phantom study. IMXT plans were created using the step-and-shoot (IMXT-SAS) and helical tomotherapy (IMXT-HT) methods. IMPT plans were created with the spot scanning (IMPT-SS) and distal gradient tracking (IMPT-DGT) methods. IMPT-DGT is a generalization of the distal edge tracking method designed to reduce the number of proton beam spots required to deliver non-uniform dose distributions relative to IMPT-SS. The IMPT methods were delivered over both 180° and 360° arcs. The IMXT-SAS and IMPT-SS methods optimally satisfied the non-uniform dose prescriptions the least and the most, respectively. The IMPT delivery methods reduced the normal tissue integral dose by a factor of about 2 relative to the IMXT delivery methods, regardless of the delivery arc. The IMPT-DGT method reduced the number of proton beam spots by a factor of about 3 relative to the IMPT-SS method.

Flynn, R. T.; Barbee, D. L.; Mackie, T. R.; Jeraj, R.

2007-10-01

208

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 1.4×1012 ph/mm2/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

209

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

210

Ion beam profiling of aspherical X-ray mirrors  

Microsoft Academic Search

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

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

2010-01-01

211

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

212

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

NASA Astrophysics Data System (ADS)

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 1017 W/cm2 to 1018 W/cm2 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.

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

213

High Intensity Light Absorption and Picosecond X-ray Radiation from Microstructured Surfaces  

NASA Astrophysics Data System (ADS)

We have characterized absorption and x-ray conversion efficiency in a novel type of nanostructured metallic surface used as a target for high-intensity laser interaction. The infrared to x-ray conversion efficiencies from the interaction of an intense 1-ps laser pulse with this nanowire structure are factors of 4 and 5 times greater than for comparable flat targets in the spectral ranges around 125 eV and above 1 keV respectively. A comparison of x-ray yield from this new nanostructure and more conventional smoke and grating surfaces was made: streak camera measurements in the 125 eV range show highest intensity emission from the nanowire target; the duration (approx. 25ps) is one third of that measured from a comparable smoke target. The duration of keV emission was less than our resolution of 8 ps. We will describe the spatial distribution of the x-ray emission, the yield dependence on the laser angle of incidence and polarization, and recent laser-light absorption measurements.

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

1996-11-01

214

A framework for 3-D coherent diffraction imaging by focused beam x-ray Bragg ptychography.  

SciTech Connect

We present the framework for convergent beam Bragg ptychography, and, using simulations, we demonstrate that nanocrystals can be ptychographically reconstructed from highly convergent x-ray Bragg diffraction. The ptychographic iterative engine is extended to three dimensions and shown to successfully reconstruct a simulated nanocrystal using overlapping raster scans with a defocused curved beam, the diameter of which matches the crystal size. This object reconstruction strategy can serve as the basis for coherent diffraction imaging experiments at coherent scanning nanoprobe x-ray sources.

Hruszkewycz, S. O.; Holt, M. V.; Tripathi, A.; Maser, J.; Fuoss, P. H. (Center for Nanoscale Materials); ( MSD); (Univ. of California at San Diego)

2011-06-15

215

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

216

Investigation of chemical vapour deposition diamond detectors by X-ray micro-beam induced current and X-ray micro-beam induced luminescence techniques  

NASA Astrophysics Data System (ADS)

Tracking detectors have become an important ingredient in high-energy physics experiments. In order to survive the harsh detection environment of the large hadron collider (LHC), trackers need to have special properties. They must be radiation hard, provide fast collection of charge, be as thin as possible and remove heat from readout electronics. The unique properties of diamond allow it to fulfill these requirements. In this work we present an investigation of the charge transport and luminescence properties of “detector grade” artificial chemical vapour deposition (CVD) diamond devices developed within the CERN RD42 collaboration, performed by means of X-ray micro-beam induced current collection (XBICC) and X-ray micro-beam induced luminescence (XBIL) techniques. XBICC technique allows quantitative estimates of the transport parameters of the material to be evaluated and mapped with micrometric spatial resolution. In particular, the high resolution and sensitivity of the technique has allowed a quantitative study of the inhomogeneity of the charge transport parameter defined as the product of mobility and lifetime for both electron and holes. XBIL represents a technique complementary to ion beam induced luminescence (IBIL), which has already been used by our group, since X-ray energy loss profile in the material is different from that of MeV ions. X-ray induced luminescence maps have been performed simultaneously with induced photocurrent maps, to correlate charge transport and induced luminescence properties of diamond. Simultaneous XBICC and XBIL maps exhibit features of partial complementarity that have been interpreted on the basis of considerations on radiative and non-radiative recombination processes which compete with charge transport efficiency.

Olivero, P.; Manfredotti, C.; Vittone, E.; Fizzotti, F.; Paolini, C.; Lo Giudice, A.; Barrett, R.; Tucoulou, R.

2004-10-01

217

Spectroscopy of X-Ray-Boosted Photoionization with an Intense Laser Pulse  

NASA Astrophysics Data System (ADS)

The present study shows that x-ray photoionization in the presence of an intense laser pulse has interesting energetic and statistical properties due to field modulation and interference between photoelectrons. The spectral cut-off energies, integral, and double integral reflect the strength, time, and interference of the laser field modulation. New methods are proposed for precise intense-laser-pulse measurement in situ. These methods have the advantages of accuracy, simplicity, speed, and large dynamic ranges.

Ge, Yu-Cheng

2013-08-01

218

Diamond monochromator for high heat flux synchrotron x-ray beams  

SciTech Connect

Single crystal silicon has been the material of choice for x-ray monochromators for the past several decades. However, the need for suitable monochromators to handle the high heat load of the next generation synchrotron x-ray beams on the one hand and the rapid and on-going advances in synthetic diamond technology on the other make a compelling case for the consideration of a diamond mollochromator system. In this Paper, we consider various aspects, advantage and disadvantages, and promises and pitfalls of such a system and evaluate the comparative an monochromator subjected to the high heat load of the most powerful x-ray beam that will become available in the next few years. The results of experiments performed to evaluate the diffraction properties of a currently available synthetic single crystal diamond are also presented. Fabrication of diamond-based monochromator is within present technical means.

Khounsary, A.M.; Smither, R.K.; Davey, S.; Purohit, A.

1992-12-01

219

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

SciTech Connect

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-{mu}m-wide beam to a width of 80 {mu}m with a photon flux density gain of 5.6 at an x-ray energy of 10 keV.

Kagoshima, Yasushi; Takano, Hidekazu [Center for Novel Material Science Under Multi-Extreme Conditions, Graduate School of Material Science, University of Hyogo, 3-2-1 Kouto, Kamigori, Ako, Hyogo 678-1297 (Japan); Takeda, Shingo [SPring-8 Service Co., Ltd, 1-20-5 Kouto, Shingu, Tatsuno, Hyogo 679-5165 (Japan)

2012-10-15

220

Generation of Phase-Coherent Soft X-Ray Laser Beams by Seeding Plasma Amplifiers  

NASA Astrophysics Data System (ADS)

Injection seeding of soft x-ray plasma amplifiers with high harmonic pulses offers important advances for applications including full spatial and temporal coherence, reduced divergence, shorter pulsewidth, and increased brightness. We report detailed measurements and simulations of the near-field and far-field beam patterns from a 13.9 nm Ni-like Ag seeded soft x-ray laser. A comparison of the ASE and seeded soft x-ray lasers beam characteristics gives insight into the underlying physics of the plasma amplifier, including the extent and duration of the gain. Model results are compared to 2D model simulations. Work supported by the NSF EUV ERC Award #EEC-0310717. M.B. was supported by DOE CSGF Grant #DE-FG02-97ER25308 References Y. Wang et al., Nature Photonics 2, 94-98 (2008) Y. Wang et al., Physical Review A, 79, 023810 (2009)

Alessi, David; Berrill, Mark; Wang, Yong; Domingue, Scott; Martz, Dale; Kemp, David; Luther, Brad; Rocca, Jorge

2009-11-01

221

Measurement and calculation of escape peak intensities in synchrotron radiation X-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

In synchrotron radiation X-ray fluorescence experiments, the escape peaks, generating from the Si(Li) solid detector, can disrupt seriously the quantitative and qualitative analysis. In this paper, 14 specimens, such as metals, compounds and plants, have been chosen as objectives to determine the intensities and positions of escape peaks. In all, the characteristic X-ray fluorescence peaks and their escape peaks of 12 elements have been measured. Comparing the experimental values with the standard values, the escape peaks can be discriminated. To calculate the ratios of intensities of the escape peaks and their corresponding characteristic X-ray fluorescence peaks, a simplified Si K/? emergent spherical distribution has been put forward. It is found that the experimental results are in accordance with that of calculation, i.e. both the experimental and theoretical ratios decrease from 1% to 0.1% with the increasing atomic number from 18 to 33 (from 1 to 9 keV in X-ray range).

Kang, S. X.; Sun, X.; Ju, X.; Huang, Y. Y.; Yao, K.; Wu, Z. Q.; Xian, D. C.

2002-06-01

222

Utilizing ablation of solids to characterize a focused soft x-ray laser beam  

NASA Astrophysics Data System (ADS)

An advanced time integrated method has been developed for soft X-ray pulsed laser beam characterization. A technique based on poly (methyl methacrylate) - PMMA laser induced ablation has been used for beam investigations of soft X-ray laser sources like FLASH (Free-electron LASer in Hamburg; formerly known as VUV FEL and/or TTF2 FEL) and plasma-based Ne-like Zn laser performed at PALS (Prague Asterix Laser System). For the interaction experiments reported here, the FLASH system provided ultra-short pulses (~10-fs) of 21.7-nm radiation. The PMMA ablation was also induced by plasma-based Ne-like Zn soft X-ray laser pumped by NIR beams at the PALS facility. This quasi-steady-state (QSS) soft X-ray laser provides 100-ps pulses of 21.2-nm radiation, i.e. at a wavelength very close to that of FLASH but with about 5,000 times longer pulses. In both cases, the PMMA samples were irradiated by a single shot with a focused beam under normal incidence conditions. Characteristics of ablated craters obtained with AFM (Atomic Force Microscope) and Nomarski microscopes were utilized for profile reconstruction and diameter determination of the focused laser beams ablating the PMMA surface.

Chalupský, J.; Juha, L.; Kuba, J.; Hájková, V.; Cihelka, J.; Homer, P.; Kozlová, M.; Mocek, T.; Polan, J.; Rus, B.; Krzywinsky, J.; Sobierajski, R.; Wabnitz, H.; Feldhaus, J.; Tiedtke, K.; the, And

2007-05-01

223

Synchrotron white beam X-ray characterization of growth defects in bulk compound semiconductors  

NASA Astrophysics Data System (ADS)

Structural defects and their distributions in bulk II-VI and III-V compound semiconductor crystals grown by different methods under different growth conditions were characterized by synchrotron white beam x-ray topography (SWBXT) and complemented by high resolution triple axis diffraction (HRTXD), optical microscopy and chemical etching techniques. In comparison with ground truth samples, Cd0.96Zn0.04 Te boules grown in microgravity by the Bridgman method exhibited a lower overall dislocation density but dislocation distribution was heterogeneous with a strong dependence on dislocation types involved, amount of wall contact, location of twinned regions and the high post-solidification cooling rates used. High mobilities of Te(g) type dislocations compared to Cd(g) (or Zn(g)) type and screw dislocations lead to different extents of deformation under equal stress levels while non-uniform wall contact produces higher stress levels in regions of wall contact. Combination of these two effects produced asymmetrically distributed deformation structures in microgravity grown crystals. Hg0.8Cd0.2Te crystals grown by the traveling heater method (THM) in a rotating magnetic field (RMF) exhibit compositional inhomogeneities, strains and high dislocation densities. By correlating with a thermo-solutal model, observed defect distribution is shown to be the result of a complex flow pattern in the solvent zone produced by the competing phenomena of buoyancy-driven and RMF-induced convection. In PVT grown ZnSe boules, defect distribution is strongly influenced by seeding and gravity vector orientation with respect to growth direction. Occurrence of twinning indicates a tendency to maintain the approximate growth axis perpendicular to the {111} planes. A novel experimental technique--synchrotron white beam x-ray anomalous scattering has been developed. This technique uses the naturally collimated synchrotron white beam to record diffracted intensities continuously as a function of wavelength and can thus map the intensity variation across the absorption edge. Using this technique, the absolute polarity of the {111} planes in LEC-grown InP has been determined. Formation of edge facets and the nucleation of twins in LEC-grown InP boules has been found to occur preferentially on {111}P faces and this is attributed to their lower surface energies.

Raghothamachar, Balaji

224

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

225

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

226

Coherent-Compton scattering for the assessment of bone mineral content using heavily filtered X-ray beams  

Microsoft Academic Search

The feasibility of using heavily filtered X-ray beams to assess trabecular bone mineral content has been investigated by measuring the ratio of coherent to incoherent scattered X-rays with a high purity Ge detector. The technique uses the strong dependence of coherent scattering on the effective atomic number of the scattering medium. With an X-ray beam filtered with a high-atomic-number filter,

D J Webster; S C Lillicrap

1985-01-01

227

Electron beam requirements for soft x-ray/XUV free-electron lasers  

SciTech Connect

A discussion of the electron beam quality (peak current, energy spread, and transverse emittance) required to drive short-wavelength free-electron lasers in the XUV (10-100 nm) and soft x-ray (<10 nm) optical wavelength ranges is presented.

Goldstein, J.C.

1987-01-01

228

ELECTRON BEAM DIAGNOSTICS WITH TRANSVERSE DEFLECTING STRUCTURES AT THE EUROPEAN X-RAY FREE ELECTRON LASER  

Microsoft Academic Search

The operation of the European X-Ray Free Electron Laser (XFEL) puts stringent demands on the peak cur- rent, transverse slice emittance and slice energy spread of the driving electron beam. For monitoring and stabilizing these parameters, dedicated diagnostic beamlines each in- cluding a horizontally operated transverse deflecting struc- ture (TDS) are planned to be installed. Observation screens downstream of the

M. Rohrs; C. Gerth

229

Microfocused X-rays Beams Using Compound Refractive Lenses: Possibilities for Indus-2  

SciTech Connect

For the generation of micro focused hard x-ray beams on Indus-2, with large depth of focus and large focal lengths, simulation studies have been performed using parabolic Be compound refractive lenses (CRLs). The use of these lenses is expected to open many new experimental possibilities widely used at other synchrotron sources.

Tiwari, M. K.; Lodha, G. S. [Indus Synchrotrons Utilisation Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India)

2011-07-15

230

Experimental ultra fast X-ray computed tomography with a linearly scanned electron beam source  

Microsoft Academic Search

We devised and tested a computed tomography approach that utilises a scanned electron beam X-ray source to produce fast tomographic image sequences of transient density distributions. Potential application areas for this technique are the visualisation and measurement of two-phase and particle flows in thermofluid dynamics research, chemical processes, or transport systems for fluids and bulk solids. In our setup we

U. Hampel; M. Speck; D. Koch; H.-J. Menz; H.-G. Mayer; J. Fietz; D. Hoppe; E. Schleicher; C. Zippe; H.-M. Prasser

2005-01-01

231

Semiconductor X-Ray Spectrometer in a Multicharged Ion Source Beam.  

National Technical Information Service (NTIS)

A Si(Li)-spectrometry technique used to study the X-ray spectra of multicharged ions, generated by an electron-beam ion source is described. The applicability of this method to ion charge state diagnostics in such a source of the type, used in a synchrotr...

V. A. Trifonov G. A. Tutin V. P. Ehjsmont E. D. Donets

1982-01-01

232

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

233

Bunch-purity measurements of synchrotron X-ray beams with an avalanche photodiode detector  

Microsoft Academic Search

The bunch purity of synchrotron X-ray beams has been measured with an avalanche photodiode (APD) detector. The APD detector has several advantages for measurements of the bunch structure in a storage ring: the detector has a good time resolution of 100 ps (FWHM) and very low noise level. Moreover, the peak profile by the present APD device has only a

Shunji Kishimoto

1994-01-01

234

Relativistic-particle beam instabilities and X-ray pulse production by the Crab pulsar  

Microsoft Academic Search

A physical mechanism based on transverse electromagnetic plasma instabilities is used to explain the origin of pulsed optical and X-ray radiation from the pulsar in the Crab Nebula. In the model, relativistic electrons or positrons counterstream or stream through an existing plasma; when the energy density of the beam exceeds the magnetic tension, the instabilities grow faster than competing electrostatic

P. E. Hardee; W. K. Rose

1974-01-01

235

Investigation of tomosynthetic perfusion measurements using the scanning-beam digital x-ray (SBDX) system  

NASA Astrophysics Data System (ADS)

The feasibility of making regional perfusion measurements using a tomosynthetic digital subtraction angiography (TDSA) acquisition has been demonstrated. The study of tomosynthetic perfusion measurements was motivated by the clinical desire for perfusion measurements in an interventional angiography suite. These pilot studies were performed using the scanning-beam digital x-ray (SBDX) system which is an inverse-geometry imaging device which utilizes an electromagnetically-scanned x-ray source, and a small CdTe direct conversion photon counting detector. The scanning electron source was used to acquire planar-tomographic images of a 12.5 x 12.5 cm field of view at a frame rate of 15 frames/sec during dynamic contrast injection. A beagle animal model was used to evaluate the tomosynthetic perfusion measurements. A manual bolus injection of iodinated contrast solution was used in order to resolve the parameters of the contrast pass curve. The acquired planar tomosynthetic dataset was reconstructed with a simple back-projection algorithm. Digital subtraction techniques were used to visualize the change in contrast agent intensity in each reconstructed plane. Given the TDSA images, region of interest based analysis was used in the selection of the image pixels corresponding to the artery and tissue bed. The mean transit time (MTT), regional cerebral blood volume (rCBV) and regional cerebral blood flow (rCBF) were extracted from the tomosynthetic data for selected regions in each of the desired reconstructed planes. For the purpose of this study, the arterial contrast enhancement curve was fit with a combination of gamma variate terms, and the MTT was calculated using a deconvolution based on the singular value decomposition (SVD). The results of the contrast pass curves derived with TDSA were consistent with the results from perfusion measurements as implemented with CT acquisition.

Nett, Brian E.; Chen, Guang-Hong; Van Lysel, Michael S.; Betts, Timothy; Speidel, Michael; Rowley, Howard A.; Aagaard Kienitz, Beverly D.; Mistretta, Charles A.

2004-10-01

236

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

237

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

238

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

239

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

PubMed

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. PMID:23205980

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

2012-11-28

240

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

241

X-ray beam stabilization at BL-17A, the protein microcrystallography beamline of the Photon Factory  

PubMed Central

BL-17A is a new structural biology beamline at the Photon Factory, Japan. The high-brilliance beam, derived from the new short-gap undulator (SGU#17), allows for unique protein crystallographic experiments such as data collection from microcrystals and structural determination using softer X-rays. However, microcrystal experiments require robust beam stability during data collection and minor fluctuations could not be ignored. Initially, significant beam instability was observed at BL-17A. The causes of the beam instability were investigated and its various sources identified. Subsequently, several effective countermeasures have been implemented, and the fluctuation of the beam intensity successfully suppressed to within 1%. Here the instability reduction techniques used at BL-17A are presented.

Igarashi, Noriyuki; Ikuta, Kazuyuki; Miyoshi, Toshinobu; Matsugaki, Naohiro; Yamada, Yusuke; Yousef, Mohammad S.; Wakatsuki, Soichi

2008-01-01

242

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

2013-01-19

243

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

244

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

SciTech Connect

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.

Landheer, Karl [Ottawa Medical Physics Institute and Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, 1125 Colonel By Drive, Ottawa K1S 5B6 (Canada); Johns, Paul C. [Ottawa Medical Physics Institute and Ottawa-Carleton Institute for Physics, Department of Physics, Carleton University, 1125 Colonel By Drive, Ottawa K1S 5B6 (Canada); Department of Radiology, University of Ottawa (Canada)

2012-09-15

245

Intense soft x-rays from RS Ophiuchi during the 1985 outburst  

SciTech Connect

Intense soft x-ray emission with a characteristic temperature of a few million degrees has been detected from the recurrent nova RS Oph approximately two months after its January 1985 optical outburst. This is the first detection of x-rays from such a system at outburst. The x-radiation is interpreted as emission from circumstellar gas that is shock heated by the passage of the blast wave from the nova explosion. The rapid decline of the x-ray flux between about 60 and 90 days after the outburst probably occurs because the blast wave has reached the edge of the volume filled, between outbursts, by the stellar wind of the red giant component of the binary system. Residual x-ray emission detected from RS Oph 250 days after the outburst is interpreted as coming from the surface of a white dwarf, at a temperature of approx.300,000K, where thermonuclear burning is persisting. 7 refs., 3 figs.

Mason, K.O.; Cordova, F.A.; Bode, M.F.; Barr, P.

1985-01-01

246

Studies of LSO:Tb radio-luminescence properties using white beam hard X-ray synchrotron irradiation  

NASA Astrophysics Data System (ADS)

A radio-luminescence set-up was installed at the synchrotron light source ANKA to characterise scintillators under the high X-ray photon flux density of white beam synchrotron radiation. The system allows for investigating the radio-luminescence spectrum of the material under study as well as analysing in situ changes of its scintillation behaviour (e.g. under heat load and/or intensive ionising radiation). In this work we applied the radio-luminescence set-up for investigating the radiation damage effects on the luminescence properties of a new kind of thin single crystal scintillator for high resolution X-ray imaging based on a layer of modified Lu2SiO5 grown by liquid phase epitaxy on a dedicated substrate within the framework of an EC project (SCINTAX).

Cecilia, A.; Rack, A.; Pelliccia, D.; Douissard, P.-A.; Martin, T.; Couchaud, M.; Dupré, K.; Baumbach, T.

247

X-ray scattering intensities of water at extreme pressure and temperature.  

PubMed

We have calculated the coherent x-ray scattering intensity of several phases of water under high pressure using the ab initio density functional theory (DFT). Our calculations span the molecular liquid, ice VII, and superionic solid phases, including the recently predicted symmetrically hydrogen bonded region. We compute simulated spectra for ice VII and superionic water. We provide new atomic scattering form factors for water at extreme conditions, which take into account frequently neglected changes in ionic charge and electron delocalization. We show that our modified atomic form factors allow for a nearly exact comparison with the total x-ray scattering intensities calculated from DFT. Finally, we analyze the effect of their new form factors have on the determination of the oxygen-oxygen radial distribution function from experiment. PMID:17430045

Goldman, Nir; Fried, Laurence E

2007-04-01

248

Vacuum ultraviolet, extreme ultraviolet, and x-ray line intensity normalization technique applied to tokamak plasmas  

NASA Astrophysics Data System (ADS)

An empirical procedure, ``LINT,'' for relating emission line intensities of intrinsic impurity ions to their elemental contributions to the total, bolometric, radiation loss and the volume-averaged effective ion charge, Zeff, has been developed and applied to limiter plasmas in the JET tokamak. In this article we discuss extensions to the data base to include x-ray lines and continua intensities, applicable to a wider range of tokamak plasma configurations such as X-point plasmas and quasi-steady-state, edge-cooled ELMy H modes. Examples are shown of the technique applied to reference discharges during which the plasma configuration is changed continuously. The total data set, comprising line and continua irradiances, tomographic bolometry, and x-ray emission and Zeff imposes constraints on the diffusion parameters used in models of impurity ion transport.

Peacock, N. J.; Lawson, K. D.; Barnsley, R.; Chen, H.

1999-01-01

249

New aspect of diffraction of a highly divergent characteristic X-ray beam  

SciTech Connect

A new way of implementing the diffraction of a highly divergent characteristic X-ray beam has been developed. This method is based on the formation of a diffraction image by the X rays exiting particular (active) points on the crystal surface which lie on hyperbolas. There is a correspondence between the points on the crystal surface and the points in the diffraction image. Local distortions of the crystal structure lead to local deviations of the diffraction lines from proper hyperbolas. This method makes it possible to reveal the block structure of crystals, separate blocks, and estimate the degree of misorientation.

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

2010-09-15

250

Phase retrieval with two-beam off-axis x-ray holography  

NASA Astrophysics Data System (ADS)

A wave front dividing x-ray interferometer with a prism was applied to two-beam off-axis holography. Complex amplitudes at the detector plane, which were derived from the hologram using the fringe scanning method, were inversely transformed to those at the exit surface of the specimen. The x-ray phase shift due to the amorphous carbon particles was quantitatively determined with the background of the phase image being as small as approximately ?/100 at 12.4 keV.

Kohmura, Yoshiki; Sakurai, Tatsuyuki; Ishikawa, Tetsuya; Suzuki, Yoshio

2004-08-01

251

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

252

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

253

Electronic structure and muonic x-ray intensities in isoelectronic series of neon and argon  

Microsoft Academic Search

We report on muonic Lyman-series x-ray intensities measured in gaseous argon and in K+, Cl-, Na+, and F- in the compounds KF and NaCl. The analysis of their structures, including neon, shows that both the spatial symmetry and the binding energy of the electrons of outer shells determine the angular momentum distribution of captured muons. The conclusions are in agreement

R. Jacot-Guillarmod; F. Bienz; M. Boschung; C. Piller; L. A. Schaller; L. Schellenberg; H. Schneuwly; D. Siradovic

1988-01-01

254

Electronic structure and muonic x-ray intensities in isoelectronic series of neon and argon  

NASA Astrophysics Data System (ADS)

We report on muonic Lyman-series x-ray intensities measured in gaseous argon and in K+, Cl-, Na+, and F- in the compounds KF and NaCl. The analysis of their structures, including neon, shows that both the spatial symmetry and the binding energy of the electrons of outer shells determine the angular momentum distribution of captured muons. The conclusions are in agreement with the modified model of ``large mesic molecules.''

Jacot-Guillarmod, R.; Bienz, F.; Boschung, M.; Piller, C.; Schaller, L. A.; Schellenberg, L.; Schneuwly, H.; Siradovic, D.

1988-05-01

255

High-temperature furnace for quantitative x-ray intensity measurements  

Microsoft Academic Search

The construction of a high-temperature diffractometer furnance for quantitative x-ray intensity measurements to above 2000°C is described. The details include descriptions of a new sample holder, the hot-zone geometry and assembly, the radiation shielding, direct temperature measurement and a continuously adjustable specimen rocking device. Emphasis has been placed upon flexibility and reliable high-temperature operation. Although the system is operated with

C R Houska; E J Keplin

1964-01-01

256

Strain analysis by inversion of coherent Bragg X-ray diffraction intensity: the illumination problem  

Microsoft Academic Search

Bragg coherent X-ray diffraction imaging is demonstrated with a micro-focused illumination. The 2D projected density of the 3D nano-crystal is successfully retrieved from the inversion of its diffraction intensity pattern. The analysis of the phase field at the sample position, which holds in principle the strain information, emphasizes the high sensitivity of the technique with regard to the wavefront structure.

V. Chamard; M. Dollé; G. Baldinozzi; F. Livet; M. de Boissieu; S. Labat; F. Picca; C. Mocuta; P. Donnadieu; T. H. Metzger

2010-01-01

257

High resolution electron beam lithography on x ray mask substrates. Effects of electron scattering and membrane heating  

Microsoft Academic Search

The requirements of X-ray masks for a 64 megabit storage in electron beam lithography, with regard to resolution power and positioning accuracy were compared with the present state of electron beam systems. Electron scattering behavior in X-ray mask substrates was examined with special emphasis on the quantification of the proximity effect. A Monte Carlo simulation program was developed. The evaluation

Klaus Reimer

1991-01-01

258

Low energy ion beam monitoring system by dosimetry film and particle induced X-ray  

Microsoft Academic Search

A simple monitoring system for a low energy (less than 5MeV) proton beam by dosimetry film was developed. A few ?m thick Ni foil was installed in front of the film to produce X-rays which develop the film. To eliminate heat damage by the ion beam, a Ni foil was prepared on a 500?m thick graphite sheet which stops the

H. W. Choi; H. J. Woo; J. H. Park; G. H. Lee; G. D. Kim; J. K. Kim; W. Hong; C. H. Eum

2007-01-01

259

Optical Design of High-Performance Beam Lines for X-Ray Lithography  

Microsoft Academic Search

In this paper is presented an optical design of high-performance beam lines for synchrotron-radiation-based X-ray lithography. The optical system is composed of a single toroidal scanning mirror and a movable beryllium window whose motions are synchronized. The use of a toroidal scanning mirror is thought to cause excessive deformation of beam shape during scanning and to suppress the light-condensing capacity.

Eijiro Toyota

1999-01-01

260

Beam characterization of a lab bench cold cathode ultra-soft X-ray generator  

NASA Astrophysics Data System (ADS)

Characterization of both spatial and dosimetric features of the beam of a customized lab bench cold-cathode ultra-soft X-ray source.Dosimetric films of GAFCHROMIC HD-810 are used to estimate both the photon spatial distribution and fluence rate of the beam.Mono-energetic source for radiobiology with an energy centred at 1.5 keV and dose rate of about 2 Gy/min.

Ounoughi, N.; Mavon, C.; Belafrites, A.; Groetz, J.-E.; Fromm, M.

2013-06-01

261

Use of Fan Beam Dual Energy X- Ray Absorptiometry to Measure Body Composition of Piglets  

Microsoft Academic Search

A piglet model was used to determine whether the fan beam dual energy X-ray absorptiometry technique (DXA) could be adapted for the measurement of body composition of small subjects. Commercial domestic swine piglets (n 14) with weights between 1.95 and 21.1 kg had duplicate fan beam-DXA scans followed by chemi- cal analysis of body composition. Each scan required 2-3 min

Winston W. K. Koo; Mouhanad Hammami; Elaine M. Hockman

262

Thermal Acoustic Sensor for High Pulse Energy X-ray FEL Beams  

SciTech Connect

The pulse energy density of X-ray FELs will saturate or destroy conventional X-ray diagnostics, and the use of large beam attenuation will result in a beam that is dominated by harmonics. We present preliminary results at the LCLS from a pulse energy detector based on the thermal acoustic effect. In this type of detector an X-ray resistant material (boron carbide in this system) intercepts the beam. The pulse heating of the target material produces an acoustic pulse that can be detected with high frequency microphones to produce a signal that is linear in the absorbed energy. The thermal acoustic detector is designed to provide first- and second-order calorimetric measurement of X-ray FEL pulse energy. The first-order calorimetry is a direct temperature measurement of a target designed to absorb all or most of the FEL pulse power with minimal heat leak. The second-order measurement detects the vibration caused by the rapid thermoelastic expansion of the target material each time it absorbs a photon pulse. Both the temperature change and the amplitude of the acoustic signal are directly related to the photon pulse energy.

Smith, T.J.; Frisch, J.C.; Kraft, E.M.; Loos, J.; /SLAC; Bentsen, G.S.; /Rochester U.

2011-12-13

263

Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-ray Preheat  

SciTech Connect

To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, <<10{sup 13} W/cm{sup 2}, compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flashcoating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe.

Colvin, J D; Kalantar, D H

2005-08-29

264

Scaling of Pressure with Intensity in Laser-Driven Shocks and Effects of Hot X-Ray Preheat  

SciTech Connect

To drive shocks into solids with a laser we either illuminate the material directly, or to get higher pressures, illuminate a plastic ablator that overlays the material of interest. In both cases the illumination intensity is low, <<1013 W/cm2, compared to that for traditional laser fusion targets. In this regime, the laser beam creates and interacts with a collisional, rather than a collisionless, plasma. We present scaling relationships for shock pressure with intensity derived from simulations for this low-intensity collisional plasma regime. In addition, sometimes the plastic-ablator targets have a thin flash-coating of Al on the plastic surface as a shine-through barrier; this Al layer can be a source of hot x-ray preheat. We discuss how the preheat affects the shock pressure, with application to simulating VISAR measurements from experiments conducted on various lasers on shock compression of Fe.

Colvin, Jeffrey D.; Kalantar, Daniel H. [Lawrence Livermore National Laboratory, L-356, P.O. Box 808, Livermore, CA 94551 (United States)

2006-07-28

265

Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy  

Microsoft Academic Search

At the time of the submission of the original proposal more than 7 years ago, the X-11 PRT had set as a goal to develop one of the leading and most comprehensive x-ray absorption beam lines in the world. By any measure we have been successful. As is well documented in previous annual progress report and in the NSLS annual

1989-01-01

266

Compact plasma focus soft x-ray source with high repetition rate and high intensity  

NASA Astrophysics Data System (ADS)

We have developed two compact plasma focus devices operating in neon with high repetition rate capacity to be used as a repetitive pulse soft x-ray (SXR) source for lithography. A single capacitor module 1-1-1 was used to test high repetitive rate capability and was observed to produce soft x-rays in the wavelength range of 0.8-1.4 nm at up to 10 Hz. The discharge current rises in 1.2 us to peak value of 140 kA at 15 kV charge. The soft x-ray yield varies with the pressure of working gas, the value and polarity of voltage applied to capacitor.On the basis of this module we have designed a our module test system for SXR designated as the NX1. The peak discharge current is 270 kA when the capacitor bank is charged to 12kV. It produces 100J of soft x-ray per shot in single shot mode, in the wavelength range of 0.8 to 1.4nm and a spot size of below 1mm viewed end on. With a repetitive rate of up to 3Hz this gives 300W of average SXR power. The NX2 is a second system that has been designed and constructed. It will be operated at peak currents in excess of 300kA into water-cooled electrodes at repetitive rates up to 20Hz to produce 300W SXR in burst durations of up to 5 minutes. It is estimated that with such a SXR yield into a well designed beamline and a reasonably sensitive resist an exposure could be made in less than 10 seconds. Pushing such x-ray sources further to 2 kW output will make their intensity sufficient for SXR lithography with reasonably high throughput to be of industrial interest.

Lee, Sing; Lee, Paul; Zhang, G. X.; Feng, X.; Serban, A.; Liu, M. H.; Wong, Terence K.; Selvam, C.; Thang, A.

1997-08-01

267

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 is considered. The importance of the time-resolved studies of matter at picosecond (ps), femtosecond (fs), and atttosecond (as) time scales using x-rays has been widely recognized including by award of a Nobel Prize in 1999 [Zewa]. Extensive reviews of scientific drivers can be found in [BES1, BES2, BES3, Lawr, Whit]. Several laser-based techniques have been used to generate ultrashort x-ray pulses including laser-driven plasmas [Murn, Alte, Risc, Rose, Zamp], high-order harmonic generation [Schn, Rund, Wang, Arpi], and laser-driven anode sources [Ande]. In addition, ultrafast streak-camera detectors have been applied at synchrotron sources to achieve temporal resolution on the picosecond time scale [Wulf, Lind1]. In this paper, we focus on a different group of techniques that are based on the use of the relativistic electron beam produced in conventional accelerators. In the first part we review several techniques that utilize spontaneous emission of electrons and show how solitary sub-ps x-ray pulses can be obtained at existing storage ring based synchrotron light sources and linacs. In the second part we consider coherent emission of electrons in the free-electron lasers (FELs) and review several techniques for a generation of solitary sub-fs x-ray pulses. Remarkably, the x-ray pulses that can be obtained with the FELs are not only significantly shorter than the ones considered in Part 1, but also carry more photons per pulse by many orders of magnitude.

Zholents, A.; Accelerator Systems Division (APS)

2010-09-30

268

Electron Beam-Target Interaction and Spot Size Stabilization in Flash X-Ray Radiography*  

NASA Astrophysics Data System (ADS)

The Dual Axis Radiographic Hydro-Test (DARHT) facility is one of the most important capabilities in science based stockpile stewardship program of the US Department of Energy. DARHT uses an intense relativistic electron beam (20 MeV, 2-4 kA) to provide the necessary dose and a very small radiation spot size ( 1 mm) to achieve the desired optical resolution. Linear induction accelerator technology and electron beam diode technology can produce beams with the desirable characteristics. However, the high current densities at the converter target will cause strong nonlinear effects, which can adversely influence the radiographic performance. Over a time scale of tens of nanoseconds, intense space charge fields of the electron beam will extract positively charged ions from the vaporized target. These ions will partially neutralize the electron beam, reducing its Coulomb self-repulsive force. Initially the beam will pinch near the target, giving a favorable reduction in spot size but possibly degrading the beam quality. The ion column will then propagate upstream, moving the location of the pinch away from the target. The beam will pinch on axis and expand, producing a progressive increase in spot size as the pinch migrates upstream. This phenomenon can severely degrade resolution. In multiple-pulse applications where longer time scale phenomena become important, the expanding plasma plume of the vaporized target material can cause disruption of subsequent electron beam pulses. In this study, we investigate the physics of beam transport and explore methods for mitigating the undesirable effects. Theoretical models have been developed and validated against available experimental data from the Los Alamos Integrated Test Stand (ITS). It is shown that ion propagation can be suppressed by applying a negative bias potential to the target. The ions then become trapped in the target vicinity and actually reduce the spot size rather than increasing it due to the additional ion focusing. The negative bias can be created by inductively isolating the target, by an external voltage source, or most simply by using charge deposition from the electron beam itself to resistively bias the target. An alternative approach utilizes a very thin upstream barrier foil that is transparent to the incoming electron beam but opaque to the lower-velocity ions. Simulations indicate that any of these methods can effectively stabilize the beam spot size. The self-biasing target concept was implemented and tested on the ITS machine and performed as predicted. Computer simulations and data from these experiments allowed us to predict the time scale for ion emission and identify the ion species present. Another key factor is the influence of beam pinch and emittance growth on the radiative output. Results from our beam transport calculations have been linked to a Monte Carlo code to analyze the quantitative impact on the x-ray output spectrum. The presentation will focus on the physics of converter targets and on designs applicable to the DARHT radiographic facility.

Kwan, Thomas J. T.

1999-11-01

269

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

PubMed

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. PMID:19810470

Hill, Robin; Mo, Zhao; Haque, Mamoon; Baldock, Clive

2009-09-01

270

Simulations of a Johann/Johansson diffraction spectrometer for x-ray experiments at an electron beam ion source  

NASA Astrophysics Data System (ADS)

The ray tracing simulations of x-ray spectra for a compact six-crystal Johann/Johansson diffraction spectrometer covering a wide photon energy range (70 eV-15 keV), i.e. from the extended ultraviolet to the hard x-ray region, are discussed in the context of x-ray experiments at an electron beam ion source facility. In particular, the x-ray line profiles and energy resolution for different diffraction crystals and multilayers were studied, and the effects of extension of x-ray source size and misalignment were investigated. The simulations were also performed for x-ray emission from solid targets bombarded by electrons, which will be used for calibration of the x-ray spectrometer.

Jab?o?ski, ?.; Jagodzi?ski, P.; Bana?, D.; Pajek, M.

2013-09-01

271

Tomographic imaging of coherent x-ray scatter momentum transfer distribution using spectral x-ray detection and polycapillary optic  

Microsoft Academic Search

Quantitation of coherent x-ray scatter traditionally involves measuring the intensity of the scattered x-ray over a range of angles (theta) from the illuminating monochromatic x-ray beam. Spectral x-ray imaging produces the same information at a single theta when bremsstrahlung x-ray exposure is used. We used a 200mum thick sheet-illumination of a phantom (lucite cylinder containing holes with water, polyethylene, collagen,

Diane R. Eaker; Steven M. Jorgensen; Anthony P. H. Butler; Erik L. Ritman

2010-01-01

272

Effect of powder sample granularity on fluorescent intensity and on thermal parameters in x-ray diffraction Rietveld analysis.  

National Technical Information Service (NTIS)

The effect of sample granularity on diffracted x-ray intensity was evaluated by measuring the 2(theta) dependence of x-ray fluorescence from various samples. Measurements were made in the symmetric geometry on samples ranging from single crystals to highl...

C. J. Sparks E. D. Specht G. E. Ice R. Kumar P. Zschack

1991-01-01

273

New method for calculating the intensities of X rays and thermal neutrons diffracted in single crystals with defects  

SciTech Connect

A new method is proposed to calculate the intensities of X rays and thermal neutrons diffracted in single crystals with defects. This method is based on comparing the dynamic theory of the Bragg diffraction of X rays and thermal neutrons in perfect single crystals with the small-angle scattering theory.

Egiazaryan, A. M.; Gevorkyan, K. M., E-mail: konstantin@iapp.sci.am; Atanesyan, A. K. [National Academy of Sciences of the Republic of Armenia, Institute of Applied Problems of Physics (Armenia)

2011-05-15

274

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

275

Shearing interferometer for quantifying the coherence of hard x-ray beams.  

PubMed

We report a quantitative measurement of the full transverse coherence function of the 14.4 keV x-ray radiation produced by an undulator at the Swiss Light Source. An x-ray grating interferometer consisting of a beam splitter phase grating and an analyzer amplitude grating has been used to measure the degree of coherence as a function of the beam separation out to 30 microm. Importantly, the technique provides a model-free and spatially resolved measurement of the complex coherence function and is not restricted to high resolution detectors and small fields of view. The spatial characterization of the wave front has important applications in discovering localized defects in beam line optics. PMID:15904233

Pfeiffer, F; Bunk, O; Schulze-Briese, C; Diaz, A; Weitkamp, T; David, C; van der Veen, J F; Vartanyants, I; Robinson, I K

2005-04-26

276

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation  

SciTech Connect

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization.

Ice, Gene E [ORNL; Larson, Ben C [ORNL; Liu, Wenjun [ORNL; Barabash, Rozaliya [ORNL; Specht, Eliot D [ORNL; Pang, Judy [ORNL; Budai, John D [ORNL; Tischler, Jonathan Zachary [ORNL; Khounsary, Ali [Argonne National Laboratory (ANL); Liu, Chian [Argonne National Laboratory (ANL); Macrander, Albert T. [Argonne National Laboratory (ANL); Assoufid, Lahsen [Argonne National Laboratory (ANL)

2007-01-01

277

Multi-species beam hardening calibration device for x-ray microtomography  

NASA Astrophysics Data System (ADS)

Impact-source X-ray microtomography (XMT) is a widely-used benchtop alternative to synchrotron radiation microtomography. Since X-rays from a tube are polychromatic, however, greyscale `beam hardening' artefacts are produced by the preferential absorption of low-energy photons in the beam path. A multi-material `carousel' test piece was developed to offer a wider range of X-ray attenuations from well-characterised filters than single-material step wedges can produce practically, and optimization software was developed to produce a beam hardening correction by use of the Nelder-Mead optimization method, tuned for specimens composed of other materials (such as hydroxyapatite [HA] or barium for dental applications.) The carousel test piece produced calibration polynomials reliably and with a significantly smaller discrepancy between the calculated and measured attenuations than the calibration step wedge previously in use. An immersion tank was constructed and used to simplify multi-material samples in order to negate the beam hardening effect of low atomic number materials within the specimen when measuring mineral concentration of higher-Z regions. When scanned in water at an acceleration voltage of 90 kV a Scanco AG hydroxyapatite / poly(methyl methacrylate) calibration phantom closely approximates a single-material system, producing accurate hydroxyapatite concentration measurements. This system can then be corrected for beam hardening for the material of interest.

Evershed, Anthony N. Z.; Mills, David; Davis, Graham

2012-10-01

278

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

279

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

SciTech Connect

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.

1995-08-01

280

X-RAY IMAGING OF THE APS STORAGE RING BEAM STABILITY EFFECTS: FROM THE ALASKAN EARTHQUAKE TO UNDULATOR FIELD CHANGES  

Microsoft Academic Search

The Advanced Photon Source (APS) 7-GeV storage ring serves as a national x-ray synchrotron radiation user facility. The stability and beam quality of the electron beam, and hence the photon beams, are monitored continuously by an array of diagnostics. In particular, x- ray imaging techniques are employed in the diagnostics EXPERIMENTAL BACKGROUND sector of the ring to characterize beam position,

A. H. Lumpkin; B. X. Yang; C. Y. Yao; L. Emery

2002-01-01

281

X-ray imaging of the APS storage ring beam stability effects: from the Alaskan earthquake to undulator field changes  

Microsoft Academic Search

The Advanced Photon Source (APS) 7-GeV storage ring serves as a national X-ray synchrotron radiation user facility. The stability and beam quality of the electron beam, and hence the photon beams, are monitored continuously by an array of diagnostics. In particular, X-ray imaging techniques are employed in the diagnostics sector of the ring to characterize beam position, size, and emittance.

A. H. Lumpkin; B. X. Yang; C. Y. Yao; L. Emery

2003-01-01

282

LabVIEW control software for scanning micro-beam X-ray fluorescence spectrometer.  

PubMed

Confocal micro-beam X-ray fluorescence microscope was constructed. The system was assembled from commercially available components - a low power X-ray tube source, polycapillary X-ray optics and silicon drift detector - controlled by an in-house developed LabVIEW software. A video camera coupled to optical microscope was utilized to display the area excited by X-ray beam. The camera image calibration and scan area definition software were also based entirely on LabVIEW code. Presently, the main area of application of the newly constructed spectrometer is 2-dimensional mapping of element distribution in environmental, biological and geological samples with micrometer spatial resolution. The hardware and the developed software can already handle volumetric 3-D confocal scans. In this work, a front panel graphical user interface as well as communication protocols between hardware components were described. Two applications of the spectrometer, to homogeneity testing of titanium layers and to imaging of various types of grains in air particulate matter collected on membrane filters, were presented. PMID:22483897

Wrobel, Pawel; Czyzycki, Mateusz; Furman, Leszek; Kolasinski, Krzysztof; Lankosz, Marek; Mrenca, Alina; Samek, Lucyna; Wegrzynek, Dariusz

2012-02-11

283

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

2012-10-24

284

Simulation study of a quasi-monochromatic beam for x-ray computed mammotomography.  

PubMed

The purpose of this simulation study was to evaluate the feasibility, benefits, and potential operating parameters of a quasi-monochromatic beam from a tungsten-target x-ray source yielding projection images. The application is intended for newly developed cone beam computed mammotomography (CmT) of an uncompressed breast. The value of a near monochromatic x-ray source for a fully 3D CmT application is the expected improved ability to separate tissues with very small differences in attenuation coefficients. The quasi-monochromatic beam is expected to yield enhanced tomographic image quality along with a low dose, equal to or less than that of dual view x-ray mammography. X-ray spectra were generated with a validated projection x-ray simulation tool (XSpect) for a range of tungsten tube potentials (40-100 kVp), filter materials (Z=51-65), and filter thicknesses (10th to 1000th value layer determined at 60 kVp). The breast was modeled from ICRU-44 breast tissue specifications, and a breast lesion was modeled as a 0.5 cm thick mass. The detector was modeled as a digital flat-panel detector with a 0.06 cm thick CsI x-ray absorption layer. Computed figures of merit (FOMs) included the ratio of mean beam energy post-breast to pre-breast and the ratio of lesion contrasts for edge-located and center-located lesions as indices of breast beam hardening, and SNR2/exposure and SNR2/dose as indices of exposure and dose efficiencies. The impact of optimization of these FOMs on lesion contrast is also examined. For all simulated filter materials at each given attenuation thickness [10th, 100th, 500th, 1000th value layers (VLs)], the mean and standard deviation of the pre-breast spectral full-width at tenth-maximum (FWTM) were 16.1 +/- 2.4, 10.3 +/- 2.2, 7.3 +/- 1.4, and 6.5 +/- 1.5 keV, respectively. The change in beam width at the tenth maximum from pre-breast to post-breast spectra ranged from 4.7 to 1.1 keV, for the thinnest and thickest filters, respectively. The higher Z filters (Z=57-63) produced a quasi-monochromatic beam that allowed the widest tube potential operating range (50-70 kVp) while maintaining minimal beam hardening and maximal SNR2/exposure and SNR2/dose, and providing a contrast greater than that obtained in the unfiltered case. Figures of merit improved with increasing filter thickness, with diminishing returns beyond the 500th value layer attenuation level. Operating parameters required to produce optimal spectra, while keeping exposures equal to that of dual view mammography, are within the capability of the commercial x-ray tube proposed for our experimental study, indicating that use of these highly attenuating filters is viable. Additional simulations comparing Mo/Mo, Mo/Rh, and W/Rh target/filter combinations indicate that they exhibit significantly lower SNR2/exposure than the present approach, precluding them from being used for computed mammotomography, while maintaining dose limitations and obtaining sufficient SNR. Beam hardening was also much higher in the existing techniques (17%-42%) than for our technique (2%). Simulations demonstrate that this quasi-monochromatic x-ray technique may enhance tissue separation for a newly developed cone beam computed mammotomography application for an uncompressed breast. PMID:15124997

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

2004-04-01

285

Applications of pixellated GaAs X-ray detectors in a synchrotron radiation beam  

NASA Astrophysics Data System (ADS)

Hybrid semiconductor pixel detectors are being investigated as imaging devices for radiography and synchrotron radiation beam applications. Based on previous work in the CERN RD19 and the UK IMPACT collaborations, a photon counting GaAs pixel detector (PCD) has been used in an X-ray powder diffraction experiment. The device consists of a 200?m thick SI-LEC GaAs detector patterned in a 64×64 array of 170?m pitch square pixels, bump-bonded to readout electronics operating in single photon counting mode. Intensity peaks in the powder diffraction pattern of KNbO3 have been resolved and compared with results using the standard scintillator, and a PCD predecessor (the ?3). The PCD shows improved speed, dynamic range, 2-D information and comparable spatial resolution to the standard scintillator based systems. It also overcomes the severe dead time limitations of the ?3 by using a shutter based acquisition mode. A brief demonstration of the possibilities of the system for dental radiography and image processing are given, showing a marked reduction in patient dose and dead time compared with film.

Watt, J.; Bates, R.; Campbell, M.; Mathieson, K.; Mikulec, B.; O'Shea, V.; Passmore, M.-S.; Schwarz, C.; Smith, K. M.; Whitehill, C.; XIMAGE Project

2001-03-01

286

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

287

Comparison of neutron and high-energy X-ray dual-beam radiography for air cargo inspection.  

PubMed

Dual-beam radiography techniques utilising various combinations of high-energy X-rays and neutrons are attractive for screening bulk cargo for contraband such as narcotics and explosives. Dual-beam radiography is an important enhancement to conventional single-beam X-ray radiography systems in that it provides additional information on the composition of the object being imaged. By comparing the attenuations of transmitted dual high-energy beams, it is possible to build a 2D image, colour coded to indicate material. Only high-energy X-rays, gamma-rays and neutrons have the required penetration to screen cargo containers. This paper reviews recent developments and applications of dual-beam radiography for air cargo inspection. These developments include dual high-energy X-ray techniques as well as fast neutron and gamma-ray (or X-ray) radiography systems. High-energy X-ray systems have the advantage of generally better penetration than neutron systems, depending on the material being interrogated. However, neutron systems have the advantage of much better sensitivity to material composition compared to dual high-energy X-ray techniques. In particular, fast neutron radiography offers the potential to discriminate between various classes of organic material, unlike dual energy X-ray techniques that realistically only offer the ability to discriminate between organic and metal objects. PMID:18054493

Liu, Y; Sowerby, B D; Tickner, J R

2007-10-22

288

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

PubMed

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. PMID:23736396

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

2013-05-20

289

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

290

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

291

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)

1999-01-01

292

CdZnTe detector array for a scanning-beam digital x-ray system  

Microsoft Academic Search

The Scanning-Beam Digital X-ray (SBDX) system promises low-dose cardiac fluoroscopy and angiography with excellent image quality. The system demands a detector capable of high count rates and excellent detection efficiency. Cadmium zinc telluride (CdZnTe) is well suited to these requirements. The SBDX detector comprises sixteen 3-mm-thick, 13.5 mm x 13.5 mm tiles arranged in a 4x4 array. Each tile has

Joseph A. Heanue; David A. Pearson; Robert E. Melen

1999-01-01

293

CdZnTe detector array for a scanning-beam digital x-ray system  

Microsoft Academic Search

The Scanning-Beam Digital X-ray (SBDX) system promises low- dose cardiac fluoroscopy and angiography with excellent image quality. The system demands a detector capable of high count rates and excellent detection efficiency. Cadmium zinc telluride (CdZnTe) is well suited to these requirements. The SBDX detector comprises sixteen 3-mm-thick, 13.5 mm X 13.5 mm tiles arranged in a 4 X 4 array.

Joseph A. Heanue; David A. Pearson; Robert E. Melen

1999-01-01

294

Design and performance of a focused beam line for surface x-ray diffraction  

Microsoft Academic Search

Focusing optics have been installed on the 5.0 T Wiggler beam line of the SRS at Daresbury Laboratory for use with x-ray diffraction measurements of surfaces and interfaces. A significant increase in the flux has been achieved without excessive degradation of the resolution in the vertical plane. The full width at half-maximum of the focused image compares well with the

C. Norris; M. S. Finney; G. F. Clark; G. Baker; P. R. Moore; R. van Silfhout

1992-01-01

295

Diffraction of a focused X-ray beam by surface acoustic waves  

Microsoft Academic Search

This paper reports the first attempt to carry out a focusing followed by a space-time scanning of a synchrotron X-ray beam. The focusing is performed through an elliptical multilayer Bragg-Fresnel lens while the space-time scanning is due to the grazing incidence diffraction on the YZ-cut of a LiNbO3 crystal modulated by pulsed surface acoustic waves. It opens the field of

R. Tucoulou; I. A. Schelokov; D. V. Roschchupkin; M. Brunel; L. Ortega; P. Chevallier

1995-01-01

296

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

297

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

298

Synchrotron radiation: micrometer-sized x-ray beams as fine tools for macromolecular crystallography.  

PubMed

Structural data play a central role in understanding biological function at the molecular level. At present, the majority of high-resolution structural data about biological macromolecules and their complexes originates from crystallography. In crystal structure determination, the major hurdle to overcome is the production of crystals of sufficient size and quality. High-flux x-ray beams with diameters of a few micrometers or less help to alleviate this problem as small beams allow the use of small crystals or scanning of large crystals for regions of acceptable diffraction. Using sophisticated x-ray optics and mechanics with submicrometer precision, Riekel et al.[Acta Crystallogr., Sect. D: Biol. Crystallogr., 64, 158-166 (2008)], have recently demonstrated that an x-ray beam of 1 mum can be used to determine the crystal structure of a protein to a resolution of 1.5 A. The smallest volume from which usable diffraction data were collected amounted to 20 mum(3), corresponding to not more than 2x10(8) unit cells. In a diffraction volume of micrometer dimensions, radiation damage is expected to be reduced with respect to large volumes as a significant fraction of the photoelectrons produced by the incident radiation escapes from the diffracting volume before dissipating their energy. The possibility to make use of small andor inhomogeneous crystals in combination with a possible reduction in radiation damage due to size effects has the potential to make many more systems amenable to crystal structure analysis. PMID:19436492

Schneider, Thomas R

2008-10-17

299

Resonant Auger Decay of Molecules in Intense X-Ray Laser Fields: Light-Induced Strong Nonadiabatic Effects  

SciTech Connect

The resonant Auger process is studied in intense x-ray laser fields. It is shown that the dressing of the initial and decaying states by the field leads to coupled complex potential surfaces which, even for diatomic molecules, possess intersections at which the nonadiabatic couplings are singular. HCl is studied as an explicit showcase example. The exact results differ qualitatively from those without rotations. A wealth of nonadiabatic phenomena is expected in decay processes in intense x-ray fields.

Cederbaum, Lorenz S.; Chiang, Ying-Chih; Demekhin, Philipp V. [Theoretische Chemie, Universitaet Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg (Germany); Moiseyev, Nimrod [Schulich Faculty of Chemistry and Minerva Center, Technion--Israel Institute of Technology, Haifa 32000 (Israel)

2011-03-25

300

Comparing different approaches to characterization of focused X-ray laser beams  

NASA Astrophysics Data System (ADS)

X-ray lasers represent a powerful tool to explore matter under extreme conditions. A rigorous characterization of their output parameters is, therefore, of substantial importance for the purposes of the experiments being conducted at these sources. A profound knowledge of the spatial, temporal, spectral, statistical, coherence, and wavefront beam properties may protect us from an unwanted misinterpretation of the experimental data. We present an experimental technique of the spatial (transverse and longitudinal) characterization of the beam profile. Investigating ablative imprints in various materials, we evaluate the spatial properties of the incident beam, namely, the beam waist radius and position, the Rayleigh range, M2 parameter, and divergence. In this paper, we recall briefly our recent work at the transverse beam profile reconstruction. A newly developed method of the longitudinal beam profile characterization is the main subject of this work.

Chalupsky, J.; Bohacek, P.; Hajkova, V.; Hau-Riege, S. P.; Heimann, P. A.; Juha, L.; Krzywinski, J.; Messerschmidt, M.; Moeller, S. P.; Nagler, B.; Rowen, M.; Schlotter, W. F.; Swiggers, M. L.; Turner, J. J.

2011-03-01

301

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

302

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

303

Supershort avalanche electron beams and x-ray in high-pressure nanosecond discharges  

NASA Astrophysics Data System (ADS)

Since 2003, an interest to investigation of e-beams generation in gas-filled diodes with high pressures has been rekindled. In 2005, the advanced recording methods of electron beams and the use of digital oscilloscopes with wide bandwidth provided the measurements of the beam current duration with time resolution of sim 100 ps. In this paper, the recent measurement results on duration and amplitude of a beam, generated at a nanosecond discharge in different gases have been summarized (Tarasenko et al. 2005, Baksht et al. 2007, Tarasenko et al. 2008). Voltage pulses sim 25, sim 150 and sim 250 kV in amplitude were applied to the gas gap with inhomogeneous electric field. It is presented that the current of supershort avalanche electrons beam (SAEB) recording through a area with a small diameter the pulse duration behind a foil from the gas diode with air at atmospheric pressure is no more than 90 ps. For recording, the pulse shape it is necessary to use a small-sized coaxial collector, loaded to a high-frequency cable, and the same collector is used for taking the charge density distribution over the foil surface in order to determine the SAEB amplitude. The electron distribution over the foil section should be compared with a per pulse distribution. In these experiments, we have compared the distributions obtained per pulse on a RF-3 and luminophore films, placed behind a foil. Besides that, intensity distribution of X-ray radiation at the gas diode output was recorded by using a multi-channel detection device based on microstrip arsenide-gallium detectors of ionizing radiation. An analysis of those data shows that at the beam current duration (FWHM) of sim 90 ps the beam current amplitude behind the 10- mu m thickness Al-foil at atmospheric pressure of air is sim 50 A. Discharge formation and SAEB generation in sulfur hexafluoride and xenon at pressure of 0.01-2.5 atm and helium of 10^-4 - 12 atm have been investigated. The beam of runaway electrons behind 45 mu m Al-Be foil was observed at sulfur hexafluoride and xenon pressure up to 2 atm. It was found that the SAEB duration (FWHM) increased with sulfur hexafluoride pressure in the range 1-2 atm. Spectra of a diffuse and contracted discharges in sulfur hexafluoride are presented. Waveforms of the electrons beams generated in helium at pressure 10^-4 - 12 atm were registered. Therewith the electrons beam in helium at p = 12 atm was obtained for the first time. Complex dependence of the electrons beam current amplitude from helium pressure was obtained. Three peaks of the current were observed at pressure 0.01, sim 0.07 and sim 3 atm.

Tarasenko, V.

2008-07-01

304

X-ray study of a test quadrant of the SODART telescopes using the expanded beam x-ray optics facility at the Daresbury synchrotron  

Microsoft Academic Search

The imaging properties of a test model of the SODART telescopes have been studied using an expanded beam X-ray facility at the Daresbury synchrotron. The encircled power and the point spread function at three energies 6.627 keV, 8.837 keV and 11.046 keV have been measured using 1D and 2D position sensitive detectors. The data have been used to calculate the

Finn E. Christensen; Allan Hornstrup; P. K. Frederiksen; Carl C. Budtz-Joergensen; Salim Abdali; P. Jonasson; P. Grundsoe; Josef Polny; N. J. Westergaard; H. U. Norgaard-Nielsen; Herbert W. Schnopper; K. N. Borozdin; C. H. Hall; R. A. Lewis

1994-01-01

305

X-ray study of a SODART flight telescope using the expanded beam x-ray optics beamline at the Daresbury synchrotron  

Microsoft Academic Search

The on- and off-axis imaging properties of the first of two SODART flight telescopes have been studied using the expanded beam x-ray facility at the Daresbury synchrotron. From on- axis measurements the encircled power distribution and the point spread function at three energies 6.627 keV, 8.837 keV, and 11.046 keV have been measured using a one dimensional position sensitive detector.

Finn E. Christensen; Allan Hornstrup; P. K. Frederiksen; Salim Abdali; P. Grundsoe; Josef Polny; N. J. Westergaard; H. U. Norgaard-Nielsen; Herbert W. Schnopper; C. Hall; R. Lewis

1995-01-01

306

Studies of electron beams and X-Rays within different plasma-focus devices  

Microsoft Academic Search

The paper presents a summary of investigations, which were performed with two mediumsize Plasma-Focus (PF) facilities, operated\\u000a at IPJ in Swierk, Poland, during the recent few years. Attention is paid to experiments performed with MAJA-PF and PF-360\\u000a devices. which were run within the energy range from 37 kJ to 170 kJ. To analyze the emitted electron beams (e-beams) and\\u000a X-rays,

J. Zebrowski; M. J. Sadowski; L. Jakubowski

2004-01-01

307

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 (??˜10eV). 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

308

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

309

An x-ray microprobe beam line for trace element analysis  

SciTech Connect

The application of synchrotron radiation to an x-ray microprobe for trace element analysis is a complementary and natural extension of existing microprobe techniques using electrons, protons, and heavier ions as excitation sources for x-ray fluorescence. The ability to focus charged particles leads to electron microprobes with spatial resolutions in the sub-micrometer range and down to 100 ppM detection limits and proton microprobes with micrometer resolution and ppM detection limits. The characteristics of synchrotron radiation that prove useful for microprobe analysis include a broad and continuous energy spectrum, a relatively small amount of radiation damage compared to that deposited by charged particles, a highly polarized source which reduces background scattered radiation in an appropriate counting geometry, and a small vertical divergence angle of approx.0.2 mrad which allows for focussing of the light beam into a small spot with high flux. The features of a dedicated x-ray microprobe beam line developed at the National Synchrotron Light Source (NSLS) are described. 4 refs., 3 figs.

Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kwiatek, W.M.; Long, G.J.; Pounds, J.G.; Schidlovsky, G.; Spanne, P.; Rivers, M.L.; Sutton, S.R.

1987-01-01

310

Multi-beam x-ray source breast tomosynthesis reconstruction with different algorithms  

NASA Astrophysics Data System (ADS)

Digital breast tomosynthesis is a new technique to improve the early detection of breast cancer by providing threedimensional reconstruction volume of the object with limited-angle projection images. This paper investigated the image reconstruction with a standard biopsy training breast phantom using a novel multi-beam X-ray sources breast tomosynthesis system. Carbon nanotube technology based X-ray tubes were lined up along a parallel-imaging geometry to decrease the motion blur. Five representative reconstruction algorithms, including back projection (BP), filtered back projection (FBP), matrix inversion tomosynthesis (MITS), maximum likelihood expectation maximization (MLEM) and simultaneous algebraic reconstruction technique (SART), were investigated to evaluate the image reconstruction of the tomosynthesis system. Reconstructed images of the masses and micro-calcification clusters embedded in the phantom were studied. The evaluated multi-beam X-ray breast tomosynthesis system is able to generate three-dimensional information of the breast phantom with clearly-identified regions of the masses and calcifications. Future study will be done soon to further improve the imaging parameters' measurement and reconstruction.

Zhou, Weihua; Qian, Xin; Lu, Jianping; Zhou, Otto; Chen, Ying

2010-03-01

311

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

312

Effects of beam-tube roughness on x-ray free electron laser performance  

NASA Astrophysics Data System (ADS)

In an x-ray free electron laser like the Linear Coherent Light Source being designed at SLAC, electron bunches about 70?m FWHM long are sent into a beam tube only 5 mm in internal diameter and more than 100 m in length. Because of the surface roughness of the beam tube, wakefields can be generated that catch up to the bunch and interact with it, causing energy spread and emittance growth. The strength of this effect depends on the details of the roughness of the surface. We present here a study in which the roughness of the beam tube was measured and the longitudinal impedance of the tube was calculated. Our result shows that a commercially available beam tube can be made smooth enough so the resulting wakefield effects are within the tolerance determined by the requirement that the induced relative energy spread of the beam be less than 5×10-4.

Stupakov, Gennady; Thomson, Ruth Ellen; Walz, Dieter; Carr, Roger

1999-06-01

313

The beam-based calibration of an X-ray pinhole camera at SSRF  

NASA Astrophysics Data System (ADS)

A pinhole camera for imaging X-ray synchrotron radiation from a dipole magnet is now in operation at the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. The electron beam size is derived by unfolding the radiation image and the point spread function (PSF) with deconvolution techniques. The performance of the pinhole is determined by the accuracy of the PSF measurement. This article will focus on a beam-based calibration scheme to measure the PSF system by varying the beam images with different quadrupole settings and fitting them with the corresponding theoretical beam sizes. Applying this method at SSRF, the PSF value of the pinhole is revised from 37 to 44 ?m. The deviation in beam size between the theoretical value and the measured value is minimized to 4% after calibration. This optimization allows us to observe the horizontal disturbance due to injection down to as small as 0.5 ?m.

Leng, Yong-Bin; Huang, Guo-Qing; Zhang, Man-Zhou; Chen, Zhi-Chu; Chen, Jie; Ye, Kai-Rong

2012-01-01

314

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

Microsoft Academic Search

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

Eun-San Kim

2007-01-01

315

Research Into Characteristics of X-Ray Emission Laser Beams from Solid-State Cathode Medium of High-Current Glow Discharge  

NASA Astrophysics Data System (ADS)

X-ray emissions ranging 1.2-3.0 keV with dose rate up to 1.0 Gy/s have been registered in experiments with high-current Glow Discharge. The emissions energy and intensity depend on the cathode material, the kind of plasma-forming gas, and the discharge parameters. The experiments were carried out on the high-current glow discharge device using D2, H2, Kr, and Xe at pressure up to 10 Torr, as well as cathode samples made from Al, Sc, Ti, Ni, Nb, Zr, Mo, Pd, Ta, W, Pt, at current up to 500 mA, and discharge voltage of 500-2500 V. Two emission modes were revealed under the experiments: (1) Diffusion X-rays was observed as separate X-ray bursts (up to 5 × 105 bursts a second and up to 106 X-ray quanta in a burst), (2) X-rays in the form of laser microbeams (up to 104 beams a second and up to 1010 X-ray of quanta in a beam, angular divergence was up to 10-4, the duration of the separate laser beams must be ? = 3 × 10-13-3 × 10-14 s, the separate beam power must be 107-108 W). The emission of the X-ray laser beams occurred when the discharge occurred and within 100 ms after turning off the current. The results of experimental research into the characteristics of secondary penetrating radiation occurring when interacting primary X-ray beams from a solid-state cathode medium with targets made of various materials are reported. It was shown that the secondary radiation consisted of fast electrons. Secondary radiation of two types was observed: (1) The emission with a continuous temporal spectrum in the form of separate bursts with intensity up to 106 fast electrons a burst. (2) The emission with a discrete temporal spectrum and emission rate up to 1010 fast electrons a burst. A third type of the penetrating radiation was observed as well. This type was recorded directly by the photomultiplier placed behind of the target without the scintillator. The abnormal high penetrating ability of this radiation type requires additional research to explain. The obtained results show that creating optically active medium with long-living metastable levels with the energy of 1.0-3.0 keV and more is possible in the solid state.

Karabut, Alexander B.

2006-02-01

316

On-axis viewing: Sample visualization along the synchrotron X-ray beam  

NASA Astrophysics Data System (ADS)

The SBC on-axis visualization system allows viewing of biological crystal samples along the X-ray beam direction, without image degradation and without parallax distortion. The on-axis system was constructed using a long working distance Maksutov-Cassegrain (MC) reflective microscope, and a right angle (45°) externally reflecting mirror. The minimum size of the right angle mirror and the maximum size of the hole through which X-rays pass depend on the sample to mirror distance as well as the required field of view and optics working distance. The on-axis system allows biological crystal visualization during diffraction data collection with full Kappa geometry without image degradation (paraxial cone rays are excluded from the image plane). On the basis of these observations it is recommended that users seriously consider on-axis reflective rather than refractive optics as the primary visualization technique.

Gofron, K. J.; Molitsky, M.; Alkire, R. W.; Joachimiak, A.

2011-09-01

317

Conceptual design of a novel instrument for producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements  

SciTech Connect

A novel bench-top device for producing intense, fast pulses of x-rays has been designed with 10 ps fwhm (full-width at half-maximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes three sections: (1) an electron gun that generates 5 ns wide pulses of 120 keV electrons at 100 kHz; (2) solenoidal magnetic lenses and deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing pulses of x-rays. At a sweeping rate of 10{sup 13} V/s, the electron pulses and resulting x-ray pulses are reduced to about 10 ps. The design process used EGUN (an electron optics and gun design program) electron trajectory simulations, including calculation of important space charge effects. When built, this instrument will be used to excite new, fast, bright scintillator samples in crystal or powdered form, allowing fluorescent lifetimes and spectra to be measured with a microchannel PMT. The very narrow 10 ps x-ray pulse width is necessary for accurate measurements of the risetimes of very fast scintillators (e.g., BaF{sub 2}). In addition, the large x-ray flux (1 A peak current) is advantageous when using a reflection grating monochromator to measure decay times at different wavelengths.

Gruber, G.J.

1996-05-01

318

X-ray and electron scattering intensities of molecules calculated using density functional theory  

NASA Astrophysics Data System (ADS)

The elastic and total intensities for x-ray and high-energy electron scattering from the ten-electron hydride series has been calculated from Kohn-Sham orbitals using the BLYP, B3LYP and LSDA functionals, and compared to the previous Hartree-Fock and singles and doubles configuration interaction (SDCI) results of Wang [J. Wang, A. N. Tripathi, and V. H. Smith, Jr., J. Chem. Phys. 101, 4842 (1994)] in the same basis. In those cases where density functional theory (DFT) provides a significantly better electron density than Hartree-Fock, the pair density and hence total scattering intensity for x-rays is also better reproduced, especially in the low s region. The asymptotic behavior of the scattering curves from the DFT methods is poorer than Hartree-Fock due to the inability of DFT to reliably predict the density at the nucleus, the electron-electron distribution at zero-electron separation, and the second moment of the electron-electron distribution.

Smith, Garry T.; Tripathi, Awadh N.; Smith, Vedene H.

1999-05-01

319

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

320

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

321

X-ray wave guiding using three-beam Bragg-surface diffraction  

NASA Astrophysics Data System (ADS)

A diffraction-type of X-ray wave guide, in contrast to refraction-type, is proposed using three-beam diffraction geometry to generate a surface diffracted beam propagating along the direction of the wave guide. The three-beam Bragg-Surface diffraction involves a symmetric Bragg reflection and a surface diffraction. The former is used to guide a wide-angle incident beam into a silicon crystal. The simultaneously occurring surface diffraction then guides the diffracted beam propagating along the direction of the wave guide that is parallel to the crystal surface. A wave guide with a shallow ditch is then manufactured along the direction of the surface diffraction using the conventional lithographic technique. As a whole the wave guide consists of a three-layer structure of tantalum/photon resist (PMMA)/tantalum, on the Silicon substrate. The surface diffracted X-rays can then be confined in and guided along the layer of photon resist. Details of the design of the wave guide and synchrotron diffraction experiments will be reported.

Chang, Shih-Lin; Zheng, Yan-Zong

2012-02-01

322

Hard X-ray generation from solids driven by relativistic intensity in the lambda-cubed regime  

NASA Astrophysics Data System (ADS)

Interaction of relativistic intensity laser pulses encompassed at focus by a volume of a few wavelengths cubed with solids is examined. Spectroscopy of hard X-rays of several metallic targets, including Cu, Ge, Mo, Ag, and Sn, irradiated in this regime at a high repetition rate (0.4 kHz), has been experimentally studied. The K? and K? peaks of all targets were obtained. Averaged electron temperatures of several tens of keV and total X-ray conversion efficiencies up to 0.02% are calculated. The X-ray source size is measured to be ˜10 micron with varying elliptical shape.

Hou, B.; Nees, J.; Mordovanakis, A.; Wilcox, M.; Mourou, G.; Chen, L. M.; Kieffer, J.-C.; Chamberlain, C. C.; Krol, A.

2006-04-01

323

Short-wavelength soft-x-ray laser pumped in double-pulse single-beam non-normal incidence  

NASA Astrophysics Data System (ADS)

We demonstrated a 7.36 nm Ni-like samarium soft-x-ray laser, pumped by 36 J of a neodymium:glass chirped-pulse amplification laser. Double-pulse single-beam non-normal-incidence pumping was applied for efficient soft-x-ray laser generation. In this case, the applied technique included a single-optic focusing geometry for large beam diameters, a single-pass grating compressor, traveling-wave tuning capability, and an optimized high-energy laser double pulse. This scheme has the potential for even shorter-wavelength soft-x-ray laser pumping.

Zimmer, D.; Ros, D.; Guilbaud, O.; Habib, J.; Kazamias, S.; Zielbauer, B.; Bagnoud, V.; Ecker, B.; Hochhaus, D. C.; Aurand, B.; Neumayer, P.; Kuehl, T.

2010-07-01

324

Time-resolved investigation of nanometer scale deformations induced by a high flux x-ray beam.  

PubMed

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. PMID:21934914

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

325

Study of X-ray polarization and e-beams generation during hot-spots formation in PF-discharges  

SciTech Connect

Strong turbulence phenomena, as observed within dense magnetized plasmas, are of interest for theoretical and experimental studies. This paper concerns the filamentation and formation of 'hot-spots' in high current PF-type discharges, as well as the emission of fast electron beams and X-ray pulses. The generation of oriented e-beams can induce the polarization of X-rays, as observed within the MAJA-PF facility at SINS.

Jakubowski, L.; Sadowski, M. [Soltan Institute for Nuclear Studies (SINS), 05-400 Otwock-Swierk (Poland); Baronova, E. O.; Vikhrev, V. V. [Nuclear Fusion Institute, RRC Kurchatov Institute, 123182 Moscow (Russian Federation)

1997-05-05

326

Generation of Powerful SubNanosecond E-Beams and X-Rays in Gas Discharges Under Atmospheric Pressure  

Microsoft Academic Search

Summary form only given. This paper reports on experimental studies the generation of sub-nanosecond electron beams and X-rays in gas discharges under atmospheric pressure (Tarasenko et al., 2005). The properties of runaway electrons and X-ray radiation produced using a nanosecond volume discharge are examined. An electron beam with amplitude of ~100 A has been obtained. Pulse duration of the fast

V. F. Tarasenko

2007-01-01

327

Radiological characterization and water equivalency of genipin gel for x-ray and electron beam dosimetry.  

PubMed

The genipin radiochromic gel offers enormous potential as a three-dimensional dosimeter in advanced radiotherapy techniques. We have used several methods (including Monte Carlo simulation), to investigate the water equivalency of genipin gel by characterizing its radiological properties, including mass and electron densities, photon interaction cross sections, mass energy absorption coefficient, effective atomic number, collisional, radiative and total mass stopping powers and electron mass scattering power. Depth doses were also calculated for clinical kilovoltage and megavoltage x-ray beams as well as megavoltage electron beams. The mass density, electron density and effective atomic number of genipin were found to differ from water by less than 2%. For energies below 150 keV, photoelectric absorption cross sections are more than 3% higher than water due to the strong dependence on atomic number. Compton scattering and pair production interaction cross sections for genipin gel differ from water by less than 1%. The mass energy absorption coefficient is approximately 3% higher than water for energies <60 keV due to the dominance of photoelectric absorption in this energy range. The electron mass stopping power and mass scattering power differ from water by approximately 0.3%. X-ray depth dose curves for genipin gel agree to within 1% with those for water. Our results demonstrate that genipin gel can be considered water equivalent for kilovoltage and megavoltage x-ray beam dosimetry. For megavoltage electron beam dosimetry, however, our results suggest that a correction factor may be needed to convert measured dose in genipin gel to that of water, since differences in some radiological properties of up to 3% compared to water are observed. Our results indicate that genipin gel exhibits greater water equivalency than polymer gels and PRESAGE formulations. PMID:21734335

Gorjiara, Tina; Hill, Robin; Kuncic, Zdenka; Bosi, Stephen; Davies, Justin B; Baldock, Clive

2011-07-06

328

Efficient E-Beam Lithography Exposure Strategies for Diffractive X-ray Optics  

SciTech Connect

Exposure of structures with rotational symmetry by means of electron beam lithography is not trivial, because the e-beam writers are usually designed to deal with the data defined in Cartesian coordinates. Fabrication of circular nanostructures like Fresnel zone plates (FZPs) for x-ray microscopy applications requires exposures with resolution well below 1 nm. Therefore, special attention has to be paid to the efficient exposure data preparation, which will guarantee required precision and allow keeping the exposure time low. In this article, we describe in detail an optimized strategy that was applied for exposure of FZPs by the Vistec EBPG5000Plus e-beam lithography tool. Direct programming of exposure files allowed us to use fully the capabilities of this e-beam writer to expose efficiently and reproducibly FZPs with desired characteristics in both positive and negative tone resists.

Guzenko, V. A.; Vila-Comamala, J.; Gorelick, S.; David, C. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Romijn, J. [Vistec Lithography B.V., 5684 PS Best (Netherlands)

2011-09-09

329

Effect of powder sample granularity on fluorescent intensity and on thermal parameters in x-ray diffraction Rietveld analysis  

Microsoft Academic Search

The effect of sample granularity on diffracted x-ray intensity was evaluated by measuring the 2θ dependence of x-ray fluorescence from various samples. Measurements were made in the symmetric geometry on samples ranging from single crystals to highly absorbing coarse powders. A characteristic shape for the absorption correction was observed. A demonstration of the sensitivity of Rietveld refined site occupation parameters

C. J. Sparks; E. D. Specht; G. E. Ice; R. Kumar; P. Zschack; T. Shiraishi; K. Hisatsune

1991-01-01

330

MSGC tests with X-rays  

NASA Astrophysics Data System (ADS)

Tests of MSGC detectors using an X-ray generator are reported. Results are presented for gas mixtures composed of Ar or Ne and dimethylether. The influence of the drift field and of the X-ray beam intensity is investigated.

Boulogne, Isabelle; Daubie, Evelyne

1998-02-01

331

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

332

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

333

An MCNP-based model of a linear accelerator x-ray beam.  

PubMed

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. PMID:10368014

Lewis, R D; Ryde, S J; Hancock, D A; Evans, C J

1999-05-01

334

Submicron stabilization of the x-ray beam position on long beamlines (abstract)  

NASA Astrophysics Data System (ADS)

The stability of the particle beam position and angle on third generation synchrotron sources such as the Advanced Photon Source (APS) at Argonne National Laboratory is extremely good. However, because of the long length of beamlines (50-70 m) at such sources, small perturbations of the particle beam angle can result in undesirable beam movement in the experimental end station. Additionally, instabilities in the beamline optics may also result in beam movement. At the BioCAT undulator source beamline at the APS, we have employed an x-ray beam position monitor (BPM) [R. Alkire, G. Rosenbaum, and G. Evans, J. Synchrotron Radiat. 7, 61 (2000)] in the experimental station at 61 m from the source to record the real time beam position in both the horizontal and vertical directions. A comparison of the rf-BPM in the storage ring and the x-ray BPM in the beamline confirm that positional changes of +/-20 ?m in the experimental end station can be traced to angular changes of +/-0.3 ?rad in the particle beam angle. Motion on this scale is particularly undesirable for small angle and solution scattering experiments that require small focal sizes on the order of 50 ?m and positional stability on the order of 5 ?m. In this article we demonstrate that the vertical beam position can be stabilizing to better than +/-1 ?m at distances of 60-70 m from the source. This was accomplished by using the position output in a closed loop feedback system to drive a piezo translator effecting the Bragg angle of the second crystal of the double crystal monochromator.

Fischetti, R. F.; Heurich, R.; Perry, D.; Stepanov, S.; Kondrashkina, E.; Rosenbaum, G.

2002-03-01

335

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.

336

Fast X-Ray Fluorescence Camera Combined with Wide Band Pass Monochromatic Synchrotron Beam  

SciTech Connect

A double W/B4C multilayer monochromator (2d=50.4A) was commissioned for non-scanning X-ray fluorescence (XRF) imaging experiments. The combination of a brilliant multi-pole wiggler source and the present wide band pass monochromator permits 1.2 x 1013 photons/sec at the sample position for 8.04 keV X-rays. Energy resolution {delta}E and {delta}E/E are 300{approx}500 eV and {approx}5%, respectively. The exit beam height is constant for X-ray energy ranging from 5.5 to 13.0 keV. Indirect cooling of the 1st multilayer works successfully. In addition, a new fast CCD camera was developed for quick readout and transfer of the image data. It was found that the typical exposure time for one XRF image with 1000 x 1000 pixels is 0.03{approx}1 sec. This permits in-situ movie recording for the distribution of elements.

Sakurai, Kenji; Mizusawa, Mari [National Institute for Materials Science, 1-2-1, Sengen, Tsukuba, Ibaraki, 305-0047 (Japan)

2004-05-12

337

Modeling of megavoltage and low energy focused x-ray beams using MCNP5  

NASA Astrophysics Data System (ADS)

In this thesis 6 and 18 MV photon beams for a Varian linear accelerator were simulated using a general purpose Monte Carlo code MCNP5 (Monte Carlo N-Particle Transport Code). The potential of MCNP5 is explored to calculate the dose in high dose gradient regions. In addition, MCNP5 was used to model another geometry, low energy focused x ray beams created with polycapillary optics, to explore their potential to provide a different skin-sparing technique for radiation therapy. Modeling was benchmarked by adjusting electron beam energy and diameter to match calculations with ionization chamber (with 0.125 cm3 sensitive volume) measurements of percent depth doses (PDDs) beyond d max and cross dose profiles at dmax and 10 cm depths for 5x5, 10x10 and 30x30 cm2 field sizes. For comparison in the buildup region, the MCNP5 voxel was reduced to 1 mm, with extrapolation to find surface dose. In this region a plane parallel chamber (with 0.055 cm3 sensitive volume) was used to measure PDDs at 0, 2 and 4 mm depths for the three field sizes, using the Khan over-response correction. Calculations and cylindrical chamber measurements for PDDs beyond d max agree within 2% for all field sizes and energies. Dose profiles agree within 2% in the flat region and within 10% in the penumbra region for all field sizes and energies. In the buildup region, the maximum deviation between MCNP5 calculations and the plane parallel PDD measurements at 18 MV is 3.8% for 30x30 cm2 at 2 mm depth. The deviation is within 3% for all other field sizes and depths for both beam energies. For 18 MV, the extrapolation of the MCNP5 PDD overestimates the surface dose for the 30x30 cm2 field size, and is within 4.6% for all other field sizes at both beam energies. A focused beam obtained with polycapillary optics was simulated using MCNP5. Low energy focused x ray beams could be used to irradiate the tumors inside soft tissue within 5 cm of the surface. A better skin sparring compared to megavoltage photon beams can be achieved by the low energy focused x ray beam inside soft tissues.

Abbas, Hassan

338

Strain field and scattered intensity profiling with energy dispersive x-ray scattering  

NASA Astrophysics Data System (ADS)

Two powerful synchrotron x-ray scattering techniques for residual strain depth-profiling and tomography-like scatter-intensity profiling of materials are presented. The techniques utilize energy dispersive x-ray scattering, from a fixed microvolume, with microscanning of the specimen being used to profile its interior. The tomography-like profiles exploit scattering-cross-section variations, and can be contrast enhanced by separately monitoring scattering from different crystal structures. The strain profiling technique is shown to finely chronicle the internal strain variation over several mm of steel. Detailed strain profiling for a cantilever spring demonstrates the interplay of residual and external stresses in elastic/plastic deformation. Since surface compression, by shot peening, is a classic method to fortify against fatigue failure, the strain profile for a shot-peened, surface-toughened material is determined and discussed in terms of a simple elastic-plastic stress/strain model. Finally the lattice strains in a WC/Co coated steel composite material are discussed.

Croft, M.; Zakharchenko, I.; Zhong, Z.; Gurlak, Y.; Hastings, J.; Hu, J.; Holtz, R.; Dasilva, M.; Tsakalakos, T.

2002-07-01

339

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

SciTech Connect

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 {mu}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 deg. can be achieved without shadowing effects and integration on-chip mixing and spectroscopy appears straightforward.

Vig, Asger Laurberg; Enevoldsen, Nikolaj; Thilsted, Anil Haraksingh; Eriksen, Johan; Kristensen, Anders [Department of Micro and Nanotechnology, DTU Nanotech, Technical University of Denmark, Building 345east, Orsteds Plads, DK-2800 Kongens Lyngby (Denmark); Haldrup, Kristoffer; Feidenhans'l, Robert; Nielsen, Martin Meedom [Centre for Molecular Movies, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen East (Denmark)

2009-11-15

340

Model independent means of categorizing X-ray binaries - I. Colour-colour-intensity diagrams  

NASA Astrophysics Data System (ADS)

The diverse behaviours displayed by X-ray binaries make it difficult to determine the nature of the underlying compact objects. In particular, identification of systems containing black holes is currently considered robust only if a dynamical mass is obtained. We explore a model-independent means of identifying the central bodies - neutron stars or black holes - of accreting binary systems. We find that four categories of object (classic black holes, GRS 1915-like black holes, pulsars and non-pulsing neutron stars) occupy distinct regions in a 3D colour-colour-intensity (CCI) diagram. Assuming that this clustering effect is due to intrinsic properties of the sources (such as mass-accretion rate, binary separation, mass ratio, magnetic field strength, etc.), we suggest possible physical effects that drive each object to its specific location in the CCI phase space. We also suggest a surface in this space which separates systems that produce jets from those which do not, and demonstrate the use of CCI for identifying X-ray pulsars where a period has not been established. This method can also be used to study subclustering within a category and may prove useful for other classes of objects, such as cataclysmic variables and active galactic nuclei.

Vrtilek, Saeqa Dil; Boroson, Bram Seth

2013-02-01

341

Dynamics of accelerated electron beams and X rays in solar flares with sub-THz radiation  

NASA Astrophysics Data System (ADS)

Unique measurements by a solar submillimeter radio telescope (SST) have been carried out in the sub-THz radiation at 212 and 405 THz over the past decade. The spectrum of RF radiation in this region increased with frequency for the three flares of November 2 and 4, 2003, and December 6, 2006, and the flux value reached 5 × 103-2 × 104 sfu at 405 GHz (Kaufman et al., 2009). In this work, we consider a set of nonlinear equations for an accelerated electrons beam and the Langmuir wave energy density. The distribution functions of the accelerated electron beam and wave energy density are calculated taking into account Coulomb collisions, electron scattering by waves, and wave scattering by plasma ions. In addition, the source of accelerated particles and the heat level of the Langmuir turbulence are specified. The beam and plasma parameters are chosen based on the aims of a problem. The plasma concentration varies from n = 1013 to 1015 cm-3, the electron plasma frequency f p = (3 × 1010-3 × 1011) Hz in this case. The ratio of plasma and beam concentrations, sufficient to explain the value of the radio flux at a frequency of 300 GHz, is n b/ n = 10-3. The Langmuir turbulence is excited due to the instability of the accelerated electron beam with an initial distribution function of the "bump-in-tail" type. Then, the parameters of radiowaves are calculated in the sub-THz range under the assumption of coalescence of two plasma waves. The calculation results show that a sub-THz radio flux can be obtained under the condition of injection of accelerated electrons. The fine time structure of radio flux observed is easily simulated based on this statement by the pulsed time structure of electron beams and their dynamics in overdense plasma. X-ray and gamma radiation was recorded during the events under study. Hard X-ray radiation is bremsstrahlung radiation from accelerated electron beams.

Vatagin, P. V.; Charikov, Yu. E.; Stepanov, A. V.; Kudryavtsev, I. V.

2012-12-01

342

Wide angle x-ray scattering of proteins : effect of beam exposure on protein integrity.  

SciTech Connect

Wide-angle X-ray scattering patterns from proteins in solution contain information relevant to the determination of protein fold. At relevant scattering angles, however, these data are weak, and the degree to which they might be used to categorize the fold of a protein is unknown. Preliminary work has been performed at the BioCAT insertion-device beamline at the Advanced Photon Source which demonstrates that one can collect X-ray scattering data from proteins in solution to spacings of at least 2.2 {angstrom} (q = 2.8 {angstrom}-1). These data are sensitive to protein conformational states, and are in good agreement with the scattering predicted by the program CRYSOL using the known three-dimensional atomic coordinates of the protein. An important issue in the exploitation of this technique as a tool for structural genomics is the extent to which the high intensity of X-rays available at third-generation synchrotron sources chemically or structurally damage proteins. Various data-collection protocols have been investigated demonstrating conditions under which structural degradation of even sensitive proteins can be minimized, making this technique a viable tool for protein fold categorization, the study of protein folding, unfolding, protein-ligand interactions and domain movement.

Fischetti, R. F.; Rodi, D. J.; Mirza, A.; Makowski, L.; Illinois Inst. of Tech.

2003-01-01

343

New configuration of photoconductive-type diamond detector head for X-ray beam position monitors  

SciTech Connect

We designed and fabricated new diamond detector head for an X-ray beam position monitor (XBPM). This monitor operates in photoconductive mode, and is shaped into a blade in order to reduce heat load. A pair of aluminum electrodes is formed on both sides of the diamond blade. The profile of the detection efficiency inside the diamond detector head was measured. The signal current is generated only between the pair of electrodes. The bias voltage dependence of signal current along a section of the detector head is also measured. The results show that the detector head operates in photoconductive mode. We demonstrated that this detector head is feasible for the XBPM.

Aoyagi, Hideki; Kudo, Togo; Tanida, Hajime [SPring-8 / JASRI, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); Kitamura, Hideo [SPring-8 / JASRI, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan); SPring-8 / RIKEN, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo 679-5148 (Japan)

2004-05-12

344

A portable molecular beam epitaxy system for in situ x-ray investigations at synchrotron beamlines  

SciTech Connect

A portable synchrotron molecular beam epitaxy (MBE) system is designed and applied for in situ investigations. The growth chamber is equipped with all the standard MBE components such as effusion cells with shutters, main shutter, cooling shroud, manipulator, reflection high energy electron diffraction setup, and pressure gauges. The characteristic feature of the system is the beryllium windows which are used for in situ x-ray measurements. An UHV sample transfer case allows in vacuo transfer of samples prepared elsewhere. We describe the system design and demonstrate its performance by investigating the annealing process of buried InGaAs self-organized quantum dots.

Slobodskyy, T. [Institute for Synchrotron Radiation, Karlsruhe Institute of Technology - 76344 Eggenstein-Leopoldshafen (Germany); Institut fuer Angewandte Physik und Zentrum fuer Mikrostrukturforschung, Jungiusstrasse 11, D-20355 Hamburg (Germany); Schroth, P.; Grigoriev, D.; Minkevich, A. A.; Baumbach, T. [Institute for Synchrotron Radiation, Karlsruhe Institute of Technology - 76344 Eggenstein-Leopoldshafen (Germany); Hu, D. Z.; Schaadt, D. M. [Institute for Applied Physics/DFG-Center for Functional Nanostructures, Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany); Institute for Energy Research and Physical Technologies, Technical University Clausthal, Am Stollen 19B, 38640 Goslar (Germany)

2012-10-15

345

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

346

Application of CdTe and CZT detectors in ultra fast electron beam X-ray tomography  

Microsoft Academic Search

Ultra fast electron beam tomography has been developed as a novel tool for visualization of fast processes. As in medical electron beam computed tomography (CT) this technique is based on the generation of images from radiographs produced with a rapidly scanned electron beam. Scanning frequencies of few thousand frames per second require X-ray detectors which can be read out at

Uwe Hampel; Frank Fischer

2008-01-01

347

Supershort avalanche electron beams and x-ray in high-pressure nanosecond discharges  

NASA Astrophysics Data System (ADS)

The properties of a supershort avalanche electron beam (S AEB) and X-ray radiation produced using a nanosecond volume discharge are examined. An electron beam of the runaway electrons with amplitude of ~ 50 A has been obtained in air atmospheric pressure. It is reported that S AEB is formed in the angle above 2? sr. Three groups of the runaway electrons are formed in a gas diode under atmospheric air pressure, when nanosecond voltage pulses with amplitude of hundreds of kilovolts are applied. The electron beam has been generated behind a 45 ?m thick AlBe foil in SF6 and Xe under the pressure of 2 arm, and in He under the pressure of about 12 atm. The paper gives the analysis of a generation mechanism of SAEB.

Tarasenko, V. F.; Baksht, E. H.; Kostyrya, I. D.; Lomaev, M. I.; Rybka, D. V.

2008-10-01

348

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

349

Investigation on the properties of a laminar grating as a soft x-ray beam splitter.  

PubMed

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 13.9 nm. 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. PMID:20697449

Liu, Ying; Fuchs, Hans-Jörg; Liu, Zhengkun; Chen, Huoyao; He, Shengnan; Fu, Shaojun; Kley, Ernst-Bernhard; Tünnermann, Andreas

2010-08-10

350

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

351

Determination of electron energy, spectral width, and beam divergence at the exit window for clinical megavoltage x-ray beams  

SciTech Connect

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 degree sign at 6 MV and 1.8 deg. 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 deg. at 6 MV and 0.1 deg. 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. [Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero Street, San Francisco, California 94143 (United States)

2009-03-15

352

Degradation of poly(methylmethacrylate) by deep ultraviolet, x-ray, electron beam, and proton beam irradiations  

Microsoft Academic Search

The chemical changes in poly(methylmethacrylate) (PMMA) caused by irradiation with deep ultraviolet (UV), x-ray, electron, and proton beams were studied by gel permeation chromatography, Fourier-transform infrared, and UV spectroscopy. The quantitative analysis of spectroscopic changes (Beer's law) demonstrated a 1:1 correspondence between the disappearance of ester groups and the generation of double bonds in the polymer chain by all types

J. O. Choi; J. A. Moore; J. C. Corelli; J. P. Silverman; H. Bakhru

1988-01-01

353

X-ray spectropolarimeter.  

PubMed

We have constructed a novel single-crystal x-ray spectropolarimeter that separates spatially the two perpendicularly polarized components of an x-ray beam. We have tested this device by using an x-ray tube, and confirmed its performance to be satisfactory as expected from its design. PMID:19044334

Baronova, E O; Stepanenko, M M; Stepanenko, A M

2008-08-01

354

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

355

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

356

Glass capillary optics for making x-ray beams of 0.1 to 50 microns diameter  

Microsoft Academic Search

We have fabricated a unique computerized glass puller that can make parabolic or elliptically tapered glass capillaries for microbeam x-ray experiments from hollow glass tubing. We have produced optics that work in a single-bounce imaging mode or in a multi-bounce condensing mode. The imaging-mode capillaries have been used to create 20 to 50 micron diameter x-ray beams at 12 keV

Donald H. Bilderback; Ernest Fontes

1997-01-01

357

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

358

Effects of radiation quality on the calibration of kerma-area product meters in x-ray beams  

Microsoft Academic Search

The calibration coefficients of kerma-area product meters significantly depend on the energy spectrum of the x-ray beam. This effect was examined by measuring the calibration coefficients for several radiation qualities in the range generally used in diagnostic x-ray imaging. The intention was to determine the calibration coefficients for other radiation qualities by interpolation between the measured values, relative to one

P. Toroi; T. Komppa; A. Kosunen; M. Tapiovaara

2008-01-01

359

Radiation-Induced Acid Generation Reactions in Chemically Amplified Resists for Electron Beam and X-Ray Lithography  

Microsoft Academic Search

The radiation-induced reactions of onium salts in some kinds of solutions and model compound solutions of chemically amplified electron beam (EB) and X-ray resists have been studied by means of picosecond and nanosecond pulse radiolysis. The following reaction mechanisms of the chemically amplified EB and X-ray resists have been elucidated. The radiation-induced reaction mechanisms are complicated due to the presence

Takahiro Kozawa; Yoichi Yoshida; Mitsuru Uesaka; Seiichi Tagawa

1992-01-01

360

Interaction of clusters with intense soft x-ray radiation from the VUV-FEL  

NASA Astrophysics Data System (ADS)

The interaction of rare gas clusters with intense vacuum ultraviolett radiation from the DESY TTF1 FEL operating at 100 nm wavelength has yielded many surprising results. For rare gas clusters unexpected high energy absorption was measured and thermionic electron emission was observed. Already at 10^13 W/cm^2 the clusters completely disintegrated in a coulomb explosion. These results indicate that for cluster in intense laser fields down to 100 nm very efficient energy absorption mechanisms exist. From a theoretical point of view new explanations for the observed energy absorption were suggested, including atomic corrections to the inverse Bremsstrahlung potentials or high intermediate charge states in the cluster. In fall 2005 the DESY VUV-FEL became operational, currently producing intense soft x-ray radiation with 32 nm wavelength and power densities of up to 10^14 W/cm^2. In the talk first results of the laser cluster interaction at this reduced wavelength will be presented. The data show less efficient energy absorption from the laser field and no thermionic electrons. The results will be discussed and compared to the 100 nm experiments.

Bostedt, Christoph

2006-05-01

361

Applications of parametric X-rays for X-ray diffraction analysis  

Microsoft Academic Search

Until now parametric X-rays (PXR) have not had practical applications because of the lack of a modern compact accelerator providing the required beam current and consequently high X-ray photon flux. PXR sources even with the intensities achievable at present may be applied to a number of X-ray reflectometry and diffractometry measurements which are important for the characterization of crystals and

I. D. Feranchuk; A. S. Lobko

2008-01-01

362

Compact soft x-ray spectrometer for plasma diagnostics at the Heidelberg Electron Beam Ion Trap.  

PubMed

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/Deltalambda approximately =130 at 2 nm and of lambda/Deltalambda approximately =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. PMID:18163718

Lapierre, A; Crespo López-Urrutia, J R; Baumann, T M; Epp, S W; Gonchar, A; González Martínez, A J; Liang, G; Rohr, A; Soria Orts, R; Simon, M C; Tawara, H; Versteegen, R; Ullrich, J

2007-12-01

363

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

Microsoft Academic Search

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

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

2004-01-01

364

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

365

X-ray imaging of a small electron beam in a low-emittance synchrotron light source  

NASA Astrophysics Data System (ADS)

We have developed the X-ray beam imager (XBI) at the SPring-8 storage ring to observe transverse profiles of a small electron beam in a low-emittance synchrotron light source. The XBI is based on a single Fresnel zone plate (FZP) and an X-ray zooming tube (XZT). The X-ray image of the electron beam moving in a bending magnet is obtained by the FZP, and it is enlarged by the XZT. Monochromatic X-rays are selected by a double crystal monochromator to avoid the effect of chromatic aberration of the FZP. The XBI has achieved a 1? spatial resolution of approximately 4 ?m, and a time resolution of 1 ms. Its field of view, which is free from vignetting, is larger than 1.5 mm in diameter on the coordinates of the electron beam. With the XBI, we have successfully measured the profiles of the electron beam of the SPring-8 and have found a vertical emittance lower than 10 pm rad at 10 mA circulating current. By utilizing the fast time resolution, we were able to study the transient behaviors of the effective beam profiles after beam injections in top-up operation at the SPring-8. In order to demonstrate the full two-dimensional imaging capability of the XBI, we also observed the dependence of the electron beam profile on the horizontal and the vertical betatron tunes.

Takano, Shiro; Masaki, Mitsuhiro; Ohkuma, Haruo

2006-01-01

366

Evaluation of soft x-ray average recombination coefficient and average charge for metallic impurities in beam-heated plasmas  

SciTech Connect

The soft x-ray continuum radiation in TFTR low density neutral beam discharges can be much lower than its theoretical value obtained by assuming a corona equilibrium. This reduced continuum radiation is caused by an ionization equilibrium shift toward lower states, which strongly changes the value of the average recombination coefficient of metallic impurities anti ..gamma.., even for only slight changes in the average charge, anti Z. The primary agent for this shift is the charge exchange between the highly ionized impurity ions and the neutral hydrogen, rather than impurity transport, because the central density of the neutral hydrogen is strongly enhanced at lower plasma densities with intense beam injection. In the extreme case of low density, high neutral beam power TFTR operation (energetic ion mode) the reduction in anti ..gamma.. can be as much as one-half to two-thirds. We calculate the parametric dependence of anti ..gamma.. and anti Z for Ti, Cr, Fe, and Ni impurities on neutral density (equivalent to beam power), electron temperature, and electron density. These values are obtained by using either a one-dimensional impurity transport code (MIST) or a zero-dimensional code with a finite particle confinement time. As an example, we show the variation of anti ..gamma.. and anti Z in different TFTR discharges.

Sesnic, S.S.; Bitter, M.; Hill, K.W.; Hiroe, S.; Hulse, R.; Shimada, M.; Stratton, B.; von Goeler, S.

1986-05-01

367

In situ x-ray study of oxide superlattice growth in reactive molecular-beam epitaxy  

NASA Astrophysics Data System (ADS)

Improper ferroelectrity found in ultrashort period PbTiO3/SrTiO3 superlattices has attracted interests as one of new `interfacially engineered' materials.[1] At the interface of PbTiO3/SrTiO3 superlattices, the coupling between the ferroelectric mode and antiferrodistortive rotations of oxygen octahedra creates improper ferroelectricity with a large dielectric constant. PbTiO3/SrTiO3 superlattices were grown using reactive molecular-beam epitaxy in a chamber with in situ x-ray diffraction capability at the Advanced Photon Source. The use of in situ surface x-ray diffraction allows one to study the evolution of oxide heterostructures. Here we present initial studies of PbTiO3 and SrTiO3 single layers as well as superlattices. [1] E. Bousquet, M. Dawber, N. Stucki, C. Lichtensteiger, P. Hermet, S. Gariglio, J.-M. Triscone, and P. Ghosez, Nature 452, 732 (2008).

Lee, June Hyuk; Chang, Seo Hyoung; Tung, I.-Cheng; Eastman, Jeff; Fong, Dillon; Freeland, John; Hong, Hawoong

2012-02-01

368

Modeling of heat-bump formation in x-ray optics under SR beams  

NASA Astrophysics Data System (ADS)

We have used a direct optical measurement of the distortion of the first silicon crystal of the CHESS A2 monochromator. The total X-ray power absorbed by the crystal was in the range of 2 to 190 Watts. The X-ray powers measured by a bolometer were in good agreement with the XOP calculations. In-situ optical measurements were used to measure the deformation of the crystal under the heat load between a 3-15° angle of incidence. Simultaneously, ANSYS modeling of the effect of the heat load on the monochromator crystal with the cooling assembly was done. The measured slope error and the surface deformation profiles were in good agreement with the ANSYS simulations. A rocking curve method was used to measure the effect of a heat load on the diffraction properties of the monochromator for a range of beam-defining slit widths. We have found a good correlation between the FWHM of the rocking curves and the slope errors from the optical measurements.

Revesz, Peter; Kazimirov, Alexander; Savino, James J.; Macgahan, Christopher J.; Windisch, Emmett L.

2009-08-01

369

Charge exchange measurements with an x-ray calorimeter at an electron beam ion trap  

NASA Astrophysics Data System (ADS)

We present K-shell x-ray spectra of highly ionized Mg acquired with the EBIT calorimeter spectrometer at a resolution of 4.5 eV in charge exchange recombination experiments using the LLNL EBIT-I electron beam ion trap. We measured the Doppler width of Mg11+ Ly? in the same experiments using a high resolution crystal spectrometer, giving an estimate of the ion temperature. We find hardness ratios for Mg11+ ranging from 0.6 to 1.6, depending on the neutral gas target. In most of the experiments, the ion temperature was ˜ 10-15 eV?amu-1, indicating that the variations in hardness ratio are intrinsic to the choice of neutral target gas, and are not simply a consequence of variations in the collision velocity resulting from evaporative cooling of the trapped ions. The spectral variations show that high resolution x-ray spectroscopy is highly diagnostic of charge exchange reactions, but requires well-developed theory to interpret.

Leutenegger, Maurice A.; Betancourt-Martinez, Gabriele L.; Beiersdorfer, Peter; Brown, Gregory V.; Kelley, Richard L.; Kilbourne, Caroline A.; Porter, F. Scott

2013-09-01

370

Strict X-ray beam collimation for facial bones examination can increase lens exposure  

PubMed Central

Objectives It is well accepted that collimation is a cost-effective dose-reducing tool for X-ray examinations. This phantom-based study investigated the impact of X-ray beam collimation on radiation dose to the lenses of the eyes and thyroid along with the effect on image quality in facial bone radiography. Methods A three-view series (occipitomental, occipitomental 30 and lateral) was investigated, and radiation doses to the lenses and thyroid were measured using an Unfors dosemeter. Images were assessed by six experienced observers using a visual grading analysis and a total of 5400 observations were made. Results Strict collimation significantly (p<0.0001) reduced the radiation dose to the lenses of the eyes and thyroid when using a fixed projection-specific exposure. With a variable exposure technique (fixed exit dose, to simulate the behaviour of an automatic exposure control), while strict collimation was again shown to reduce thyroid dose, higher lens doses were demonstrated when compared with larger fields of exposure. Image quality was found to significantly improve using strict collimation, with observer preference being demonstrated using visual grading characteristic curves. Conclusion The complexities of optimising radiographic techniques have been shown and the data presented emphasise the importance of examining dose-reducing strategies in a comprehensive way.

Powys, R; Robinson, J; Kench, P L; Ryan, J; Brennan, P C

2012-01-01

371

X-ray zone plate fabrication using a focused ion beam  

SciTech Connect

An x-ray zone plate was fabricated using the novel approach of focused ion beam (FIB) milling. The FIB technique was developed in recent years, it has been successfully used for transmission electron microscopy (TEM) sample preparation, lithographic mask repair, and failure analysis of semiconductor devices. During FIB milling, material is removed by the physical sputtering action of ion bombardment. The sputter yield is high enough to remove a substantial amount of material, therefore FIB can perform a direct patterning with submicron accuracy. The authors succeeded in fabricating an x-ray phase zone plate using the Micrion 9500HT FIB station, which has a 50 kV Ga{sup +} column. Circular Fresnel zones were milled in a 1.0-{micro}m-thick TaSiN film deposited on a silicon wafer. The outermost zone width of the zone plate is 170 nm at a radius of 60 {micro}m. An achieved aspect ratio was 6:1.

Ilinski, P. P.; Lai, B.; Bassom, N. J.; Donald, J.; Athas, G.

2000-08-16

372

Intensity-modulated x-ray (IMXT) versus proton (IMPT) therapy for theragnostic hypoxia-based dose painting  

NASA Astrophysics Data System (ADS)

In this work the abilities of intensity-modulated x-ray therapy (IMXT) and intensity-modulated proton therapy (IMPT) to deliver boosts based on theragnostic imaging were assessed. Theragnostic imaging is the use of functional or molecular imaging data for prescribing radiation dose distributions. Distal gradient tracking, an IMPT method designed for the delivery of non-uniform dose distributions, was assessed. Dose prescriptions for a hypoxic region in a head and neck squamous cell carcinoma patient were designed to either uniformly boost the region or redistribute the dose based on positron emission tomography (PET) images of the 61Cu(II)-diacetyl-bis(N4-methylthiosemicarbazone) (61Cu-ATSM) hypoxia surrogate. Treatment plans for the prescriptions were created for four different delivery methods: IMXT delivered with step-and-shoot and with helical tomotherapy, and IMPT delivered with spot scanning and distal gradient tracking. IMXT and IMPT delivered comparable dose distributions within the boost region for both uniform and redistributed theragnostic boosts. Normal tissue integral dose was lower by a factor of up to 3 for IMPT relative to the IMXT. For all delivery methods, the mean dose to the nearby organs at risk changed by less than 2 Gy for redistributed versus uniform boosts. The distal gradient tracking method resulted in comparable plans to the spot scanning method while reducing the number of proton beam spots by a factor of over 3.

Flynn, Ryan T.; Bowen, Stephen R.; Bentzen, Søren M.; Rockwell Mackie, T.; Jeraj, Robert

2008-08-01

373

A soft X-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter  

NASA Astrophysics Data System (ADS)

A soft X-ray, beam-splitting, multilayer optic has been developed for the Bragg Reflection Polarimeter (BRP) on the NASA Gravity and Extreme Magnetism Small Explorer Mission (GEMS). The optic is designed to reflect 0.5 keV X-rays through a angle to the BRP detector, and transmit 2-10 keV X-rays to the primary polarimeter. The transmission requirement prevents the use of a thick substrate, so a 2 ?m thick polyimide membrane was used. Atomic force microscopy has shown the membrane to possess high spatial frequency roughness less than 0.2 nm rms, permitting adequate X-ray reflectance. A multilayer thin film was especially developed and deposited via magnetron sputtering with reflectance and transmission properties that satisfy the BRP requirements and with near-zero stress. Reflectance and transmission measurements of BRP prototype elements closely match theoretical predictions, both before and after rigorous environmental testing.

Allured, Ryan; Fernández-Perea, Mónica; Soufli, Regina; Alameda, Jennifer B.; Pivovaroff, Michael J.; Gullikson, Eric M.; Kaaret, Philip

2013-08-01

374

Comparison of SOFC Cathode Microstructure Quantified using X-ray Nanotomography and Focused Ioni Beam-scanning Electron Microscopy  

SciTech Connect

X-ray nanotomography and focused ion beam scanning electron microscopy (FIB-SEM) have been applied to investigate the complex 3D microstructure of solid oxide fuel cell (SOFC) electrodes at spatial resolutions of 45 nm and below. The application of near edge differential absorption for x-ray nanotomography and energy selected backscatter detection for FIB-SEM enable elemental mapping within the microstructure. Using these methods, non-destructive 3D x-ray imaging and FIB-SEM serial sectioning have been applied to compare three-dimensional elemental mapping of the LSM, YSZ, and pore phases in the SOFC cathode microstructure. The microstructural characterization of an SOFC cathode is reported based on these measurements. The results presented demonstrate the viability of x-ray nanotomography as a quantitative characterization technique and provide key insights into the SOFC cathode microstructure.

G Nelson; W Harris; J Lombardo; J Izzo Jr.; W Chiu; P Tanasini; M Cantoni; J Van herle; C Comninellis; et al.

2011-12-31

375

A soft x-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter  

NASA Astrophysics Data System (ADS)

A soft X-ray, beam-splitting, multilayer optic has been developed for the Bragg Reflection Polarimeter on the NASA Gravity and Extreme Magnetism Small Explorer Mission (GEMS). The optic is designed to reflect 0.5 keV X-rays through a 90 degree angle to the BRP detector, and transmit 2-10 keV X-rays to the primary polarimeter. A transmission requirement prevents the use of a thick substrate, so a 2 µm thick polyimide membrane was used. Atomic force microscopy has shown the membrane to possess high spatial frequency roughness less than 0.2 nm rms, permitting adequate X-ray reflectance. A multilayer thin film was especially developed with reflectance and transmission properties that satisfy the BRP requirements and with near-zero stress. Multilayer depositions for prototype reflectors have been performed via magnetron sputtering. Reflectivity and transmission measurements closely match theoretical predictions, both before and after rigorous environmental testing.

Allured, Ryan; Fernández-Perea, Mónica; Soufli, Regina; Alameda, Jennifer B.; Maxwell, Alicia; Pivovaroff, Michael J.; Gullikson, Eric M.; Kaaret, Philip

2012-10-01

376

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

377

Experimental spectral measurements of heavy K-edge filtered beams for x-ray computed mammotomography  

PubMed Central

A dual modality computed mammotomography (CmT) and single photon emission computed tomography (SPECT) system for dedicated 3D breast imaging is in development. Using heavy K-edge filtration, the CmT component narrows the energy spectrum of the cone-shaped x-ray beam incident on the patient’s pendant, uncompressed breast. This quasi-monochromatic beam is expected to improve discrimination of tissue with similar attenuation coefficients while restraining absorbed dose to below that of dual view mammography. Previous simulation studies showed the optimal energy that maximizes dose efficiency for a 50/50% adipose/glandular breast is between 30 and 40 keV. This study experimentally validates these results using pre-breast and post-breast spectral measurements made under tungsten tube voltages between 40 and 100 kVp using filter materials with K-edge values ranging from 15 to 70 keV. Different filter material thicknesses are used, approximately equivalent to the 200th and 500th attenuating value layer (VL) thickness. Cerium (K = 40.4 keV) filtered post-breast spectra for 8–18 cm breasts are measured for a range of breast compositions. Figures of merit include mean beam energy, spectral full-width at tenth-maximum, beam hardening and dose for the range of breast sizes. Measurements corroborate simulation results, indicating that for a given dose, a 200th VL of cerium filtration may have optimal performance in the dedicated mammotomography paradigm.

Crotty, D J; McKinley, R L; Tornai, M P

2012-01-01

378

Intense nanosecond duration source of x rays for resolving cavitation-induced trauma in human tissue  

NASA Astrophysics Data System (ADS)

A pulsed nanosecond x-ray generator based on an actively pumped field emission x-ray tube is described. The x-ray source is based on a high voltage Marx generator that drives a field emission tube without the need for an intermediate energy store. The Marx generator stores 12 Joules in ceramic capacitors and produces a voltage pulse > 380 kilovolts with a rise time of < 4 nanoseconds from an equivalent generator-impedance of 52 W. A numerical model is used in which the x-ray tube's cathode width and anode-cathode gap (AK) are permitted to change with time while electron current between the cathode and anode is treated as non relativistic and space-charge-limited (SCL). By coupling this model to an equivalent circuit representation of the Marx generator a calculation of the cathode current, anode-cathode potential and the output x-ray spectrum can be made. The radiation dose is 55 millirems at 30.4 cm from the anode of the x-ray tube and is Gaussian in shape with a 35 nanosecond (full width at half maximum) FWHM. The measured x-ray dose, pulse shape and width are consistent with model predictions. The source was successfully used to study high-velocity projectile induced cavatation in human tissue.

Boyer, Craig N.; Holland, Glenn E.; Seely, John F.

2004-11-01

379

Phase Contrast Cone Beam Tomography with an X-Ray Grating Interferometer  

NASA Astrophysics Data System (ADS)

We report on our recent developments of reconstruction algorithms for Differential Phase Contrast X-ray Computed Tomography (DPC CT). DPC images provide information about the real and imaginary part of the refractive index which is an advantage when objects with poor absorption but good phase contrast are inspected. In order to promote DPC CT for industrial applications we developed an adapted Feldkamp algorithm which allows reconstructing the three-dimensional image of the refractive index of an object from the DPC projections obtained with our large field of view, high energy grating interferometer set up in a cone beam geometry. We present slice images of a test object and show different ways of visualization of the phase and absorption information.

Jerjen, I.; Revol, V.; Kottler, C.; Luethi, Th.; Sennhauser, U.; Kaufmann, R.; Urban, C.

2010-04-01

380

A Vlasov Solver for Longitudinal Dynamcis in Beam Delivery Systemsfor X-Ray FELs  

SciTech Connect

Direct numerical methods for solving the Vlasov equationoffer some advantages over macroparticle simulations, as they do notsuffer from the consequences of the statistical fluctuations inherent inusing a number of macroparticles smaller than thebunch population.Unfortunately these methods are more time-consuming and generallyconsidered impractical in a full 6D phase space. However, in alower-dimension phase space they may become attractive if the beamdynamics is sensitive to the presence of small charge-densityfluctuations and a high resolution is needed. In this paper we present a2D Vlasov solverfor studying the longitudinal beam dynamics insingle-pass systems of interest for X-Ray FELs, where characterization ofthe microbunching instability stemming from self-field amplified noise isof particular relevance.

Venturini, Marco; Warnock, Robert; Zholents, Alexander

2007-05-09

381

Development of X-ray Beam Position Monitors for Superconducting Wiggler  

SciTech Connect

For the development of an X-ray beam position monitor (XBPM) for the superconducting wiggler (SW) at the NSRRC, two XBPM are installed in the SW front end. The blades of the XBPM were manufactured with material of three types; tungsten, Glidcop and aluminium, to test the effect of the material on the performance of the XBPM. These three materials are compared with blades of molybdenum that were previously installed. The vibration and thermal expansion of the pillar of a XBPM affects the position reading of the XBPM. For pillars of XBPM of various designs, each type has a distinct thermal isolating material and is filled with a separate damping material for comparison. The design requirements of these XBPM include high spatial resolution of the monitor and mechanical stability of the structure with a large thermal load. The design, fabrication and measurement results are presented here.

Kuan, C.-K.; Sheng, I. C.; Lai, W.-Y.; Cheng, Y.-T.; Chen, C.-L.; Hsiung, G.-Y. [National Synchrotron Radiation Research Center, 101 Hsin-ann Road, Hsinchu Science Park, Hsinchu, 30076 Taiwan (China); Chen, J.-R. [National Synchrotron Radiation Research Center, 101 Hsin-ann Road, Hsinchu Science Park, Hsinchu, 30076 Taiwan (China); Department of Biomedical Engineering and Environmental Sciences, National Tsing-Hua University, Hsinchu, 30013 Taiwan (China)

2010-06-23

382

Particle-induced x-ray emission in stainless steel using 30 keV Ga{sup +} focused ion beams  

SciTech Connect

Characteristic x-ray emission from a well grounded stainless steel specimen using standard 30 keV Ga{sup +} focused ion beam instrumentation is demonstrated. X-ray yields are found to be on the order of 10{sup -10} per incident ion, consistent with previous studies of low energy, high mass ion-solid interactions. X-ray yields were found to be highest for low energy transitions or low atomic number target atoms. Bremsstrahlung x-ray emission was found to be minimal, possibly increasing detectability compared with electron beam induced x-rays. Yields were also estimated to be on the order of 10{sup -11} per sputtered atom, or approximately one x-ray per sputtered monolayer. While velocity coupling between the primary ion beam and target atom electrons is not possible under these experimental conditions, it is argued that x-ray emission is, in fact, due to recoil effects of the ion-solid interaction.

Giannuzzi, Lucille A.; Gorman, Brian P. [FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, Oregon 97124 (United States); Department of Materials Science and Engineering, University of North Texas, 1155 Union Circle 305310, Denton, Texas 76203 (United States)

2009-07-15

383

Time-resolved x-ray line emission studies of thermal transport in multiple beam uv-irradiated targets  

SciTech Connect

Thermal transport in spherical targets irradiated with multiple, nanosecond duration laser beams, has been a topic of much discussion recently. Different inferences on the level of thermal flux inhibition have been drawn from plasma velocity and x-ray spectroscopic diagnostics. We present new measurements of thermal transport on spherical targets made through time-resolved x-ray spectroscopic measurements of the progress of the ablation surface through thin layers of material on the surface of the target. These measurements, made with 6 and 12 uv (351 nm) nanosecond beams from OMEGA, will be compared to previous thermal transport measurements. Transparencies of the conference presentation are given.

Jaanimagi, P.A.; Henke, B.L.; Delettrez, J.; Richardson, M.C.

1984-01-01

384

A simple soft X-ray (1 < ? < 11 nm) spectrometer for relative line intensity measurements in charge exchange studies  

NASA Astrophysics Data System (ADS)

We describe a simple plane crystal spectrometer specially built for charge exchange study through soft X-ray deexcitation of highly charged ions. The use of low energy, highly charged ions incident on He and H2 targets decreases the number of processes leading to photon emission. Thus, the X-ray spectra are simple and we demonstrate that a moderate resolution spectrometer is sufficient. The instrumental relative sensitivity has been measured in the 1 to 11 nm wavelength range and a good agreement has been found with calculated values. Using the ``linear mix'' deconvolution procedure described by Henke, we made accurate measurements for the X-ray transition intensities in N7+, O8+, Ne8+ -He, H2 collision cases.

Fleury, A.; Debernardi, J.; Bonnefoy, M.; Bliman, S.; Bonnet, J. J.; Chassevent, M.

1986-03-01

385

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

386

Hot electron and x-ray production from intense laser irradiation of wavelength-scale polystyrene spheres  

NASA Astrophysics Data System (ADS)

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 2×1017 W/cm2 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 ?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.

2007-06-01

387

Bremsstrahlung X ray mappings of an intense, widespread, and pulsating electron precipitation event following a sudden commencement  

SciTech Connect

For the first time, remote bremsstrahlung X ray spatial, temporal, and spectral mappings from a satellite are presented for a strong energetic electron precipitation event following a sudden commencement. After the sudden commencement of July 13, 1982, and at the beginning of a magnetospheric substorm, X rays were observed over a period of more than 4 min from the P78-1 spacecraft at 600-km altitude. The X rays above 21 keV were emitted over a magnetic local time (MLT) interval spanning 6 hours. Five precipitating temporal spikes were observed with coherency over wide longitude intervals of 3 hours or more in MLT near midnight. The energy spectra over broad longitude intervals tended to be harder simultaneously at the times of greatest X ray intensity. The power input to the atmosphere from precipitating electrons that produced the X rays emitted within 2200--2230 MLT is estimated to have reached values of 5 x 10/sup 16/ ergs/s over an area of about 3 x 10/sup 4/ km/sup 2/, leading to an average energy deposition rate of about 160 ergs/cm/sup 2/ s. The precipitation inputs at other magnetic local times displayed nearly simultaneous sharp maxima in time but with lower power inputs. copyright American Geophysical Union 1987

Imhof, W.L.; Voss, H.D.; Mobilia, J.; Datlowe, D.W.

1987-02-01

388

Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber  

SciTech Connect

Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton{sup Registered-Sign} windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup.

Manova, D.; Bergmann, A.; Maendl, S.; Neumann, H.; Rauschenbach, B. [Leibniz-Institut fuer Oberflaechenmodifizierung e. V., Permoserstr. 15, 04318 Leipzig (Germany)

2012-11-15

389

Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber.  

PubMed

Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton(®) windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup. PMID:23206070

Manova, D; Bergmann, A; Mändl, S; Neumann, H; Rauschenbach, B

2012-11-01

390

Theoretical polarization-dependent X-ray spectra of Be-like Fe calculated for different electron beam densities  

NASA Astrophysics Data System (ADS)

We study theoretically the polarization properties of X-ray spectra of Be-like Fe ions excited through resonant capture by an electron beam with different electron densities. Our previous work in this area was related to the study of polarization of dielectronic satellite lines of Fe ions excited by a low-density electron beam. (A.S. Shlyaptseva, R.C. Mancini, P. Neill, P. Beiersdorfer, J.R. Crespo López-Urrutia, and K. Widmann, Phys. Rev. A, 57), 888 (1998) Here we extend our work to the case of higher-density electron beams. As the density of the electron beam increases, new channels of electron capture appear. Thus the atomic and polarization characteristics of the satellite lines change. Moreover, additional X-ray satellite lines will appear. Using the density matrix formalism, we calculate the polarization characteristics and polarization-dependent spectra of dielectronic satellite lines of Be-like Fe produced at different energies and densities of the electron beam. We compare the results of the present work with our previous ones for low-density electron beams. These results are relevant to the identification of X-ray polarization-dependent spectral features and for X-ray line polarization spectroscopy.

Shlyaptseva, Alla; Mancini, Roberto

1998-05-01

391

Above-threshold double ionization of helium with attosecond intense soft x-ray pulses  

SciTech Connect

We theoretically study a process in which helium is doubly ionized by absorbing two soft x-ray (91.45 eV) photons from attosecond, intense high-order harmonic sources. We directly solve the time-dependent Schroedinger equation and obtain electron energy distribution in the double continuum. Our results show that between the two peaks in electron energy spectra, expected for usual sequential ionization, an additional component (anomalous component) is present. The total two photon above-threshold double ionization yield including the anomalous component is explained by sequential processes: the two electrons are ejected one by one, absorbing a single photon each. This observation rejects the intuition that nonsequential double ionization would be responsible for the anomalous component. With the help of simple semiclassical stochastic models, we discuss two possible origins of the anomalous component, namely, postionization energy exchange and second ionization during core relaxation, of which the latter is more plausible: the ionization interval is so short that the second electron is ejected while the two electrons are still exchanging energy.

Ishikawa, Kenichi L.; Midorikawa, Katsumi [Department of Quantum Engineering and Systems Science, Graduate School of Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan); Laser Technology Laboratory, RIKEN, Institute of Physical and Chemical Research, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan)

2005-07-15

392

X-ray beam-position monitoring in the sub-micrometre and sub-second regime.  

PubMed

It is demonstrated that X-ray beam positions can be extracted from two-dimensional profiles with sub-pixel resolution. Beam-position measurements utilizing a self-designed low-cost two-dimensional detector have been performed at two synchrotron radiation beamlines of the Swiss Light Source. The effective detector pixel size was 4.8 microm and the resolution achieved for the beam position was about 5 nm. At a data rate of 25 frames per second, periodic variations of the beam position could be detected with a frequency resolution below 0.1 Hz. This allowed, for example, the influence of a turbo-pump in the X-ray optics hutch on the beam position to be quantified, and even minute variations related to the electron beam in the storage ring could be detected. PMID:16239750

Bunk, Oliver; Pfeiffer, Franz; Stampanoni, Marco; Patterson, Bruce D; Schulze-Briese, Clemens; David, Christian

2005-10-18

393

Phase retrieval in x-ray lensless holography by reference beam tuning  

SciTech Connect

We show the ability to determine the relative phase between the object and a reference scatterer by tuning the overall intensity and phase of the reference wave. The proposed reference-guided phase retrieval algorithm uses the relative phase as a constraint to iteratively reconstruct the object and the reference simultaneously, and thus does not require precisely defined reference structures. The algorithm also features rapid and reliable convergence and overcomes the uniqueness problem. The method is demonstrated by a soft-x-ray coherent imaging experiment that utilizes a large micrometer-sized reference structure that can be turned on and off, yielding an object image with resolution close to the reconstruction pixel size of 21 nm.

Zhu, D. L.

2010-02-24

394

Experimental two-phase flow measurement using ultra fast limited-angle-type electron beam X-ray computed tomography  

Microsoft Academic Search

An experimental evaluation of a novel limited-angle-type ultra fast electron beam X-ray computed tomography approach for the\\u000a visualization and measurement of a gas–liquid two-phase flow is reported here. With this method, a simple linear electron\\u000a beam scan is used to produce instantaneous radiographic views of a two-phase flow in a pipe segment of a flow loop. Electron\\u000a beam scanning can

M. Bieberle; F. Fischer; E. Schleicher; D. Koch; H.-J. Menz; H.-G. Mayer; U. Hampel

2009-01-01

395

Periodic Modulation of X-Ray Intensity from Coronal Loops – Heating by Resonant Absorption?  

Microsoft Academic Search

We have applied time-series analysis to sequences of coronal loop images obtained with the Yohkoh soft X-ray telescope (SXT). Using images obtained in fast-cadence mode (d t = 4 s), we have generated X-ray light curves and power spectra for multiple subregions of a number of coronal loops. Our analysis indicates that out of 544 spectra of loops which range

D. E. McKenzie; D. J. Mullan

1997-01-01

396

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 inertial confinement fusion (ICF). Z pinches can provide x-ray powers of 200 TW and x-ray energies approaching 2 MJ. Computational capabilities have advanced to the point that 2-D radiation magneto-hydrodynamics computer codes can be used as detailed design tools. Several ICF configurations have been proposed. The z-pinch

R B Spielman; C Deeney; M R Douglas; G A Chandler; M E Cuneo; T J Nash; J L Porter; L E Ruggles; T W L Sanford; W A Stygar; K W Struve; M K Matzen; D H McDaniel; D L Peterson; J H Hammer

2000-01-01

397

Spectroscopic Analysis of Electron Beam Diodes for Flash X-ray Radiography at Sandia National Laboratories*  

NASA Astrophysics Data System (ADS)

Experiments were performed on RITS-3, a Marx driven, three stage IVA (5.5MV, 120kA), and are continuing on RITS-6, a six stage IVA (10MV, 120kA), to study the role of plasma formation and propagation on electron beam focusing for flash x-ray radiography. It is believed that plasmas formed on electrodes or by interactions with background gases limit e-beam focusing and stability and cause pulse shortening of the diode. These are concerns as higher doses (1000 Rad at 1m) from smaller sources (2mm dia.) are required for future radiographic applications. Diagnostics include time and space resolved visible and uv emission spectra using 1 meter Czerny-Turner monochromators equipped with framing and streak cameras. Line and continuum analysis are conducted using a time-dependent CR model. Self-consistent line shape calculations measure Stark, Doppler, and opacity broadening. Electron density and temperature determinations as well as neutral and ion species parameters are obtained. Such data is crucial to the fundamental understanding of electron beam diode behavior and aids in the continued development of these sources. *Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94-AL85000.

Johnston, M. D.; Oliver, B. V.; Hahn, K.; Rovang, D.; Maenchen, J. E.; Droemer, D.; Welch, D. R.; Maron, Y.

2006-10-01

398

Low-intensity x-ray-imaging scope (Lixiscope)Its applications in sports medicine and orthopaedic surgery  

Microsoft Academic Search

The low-intensity x-ray imaging scope (Lixiscope) is a hand-held, totally portable fluorescopic device utiliz ing a low-energy, low-intensity y source of 125I. The unit was developed at the Goddard Space Flight Cen ter for the National Aeronautics and Space Adminis tration. It has become apparent that there is increasing use of this tool, especially in sports medicine, to diagnose and

William J. Tansey

1981-01-01

399

Glass capillary optics for making x-ray beams of 0.1 to 50 microns diameter  

SciTech Connect

We have fabricated a unique computerized glass puller that can make parabolic or elliptically tapered glass capillaries for microbeam x-ray experiments from hollow glass tubing. We have produced optics that work in a single-bounce imaging mode or in a multi-bounce condensing mode. The imaging-mode capillaries have been used to create 20 to 50 micron diameter x-ray beams at 12 keV that are quite useful for imaging diffraction patterns from tiny bundles of carbon and Kevlar fibers. The condensing-mode capillaries are useful for creating submicron diameter beams and show great promise in x-ray fluorescence applications with femtogram sensitivity for patterned Er and Ti dopants diffused into an optically-active lithium niobate wafer.

Bilderback, Donald H.; Fontes, Ernest [Cornell High Energy Synchrotron Source (CHESS) and School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853 (United States)

1997-07-01

400

Shielding requirements for constant-potential diagnostic x-ray beams determined by a Monte Carlo calculation.  

PubMed

A Monte Carlo calculation has been performed to determine the transmission of broad constant-potential x-ray beams through Pb, concrete, gypsum wallboard, steel and plate glass. The EGS4 code system was used with a simple broad-beam geometric model to generate exposure transmission curves for published 70, 100, 120 and 140-kVcp x-ray spectra. These curves are compared to measured three-phase generated x-ray transmission data in the literature and found to be reasonable. For calculation ease the data are fit to an equation previously shown to describe such curves quite well. These calculated transmission data are then used to create three-phase shielding tables for Pb and concrete, as well as other materials not available in Report No. 49 of the NCRP. PMID:2917843

Simpkin, D J

1989-02-01

401

A new bend magnet beam line for scanning transmission x-ray microscopy at the Advanced Light Source  

SciTech Connect

The high brightness of the bend magnets at the Advanced Light Source has been exploited to illuminate a Scanning Transmission X-ray Microscope (STXM). This is the first diffraction-limited scanning x-ray microscope to operate with useful count rate on a synchrotron bend magnet source. A simple, dedicated beam line has been built covering the range of photon energy from 250 eV to 600 eV. Ease of use and operational availability are radically improved compared to previous installations using undulator beams. This facility provides radiation for C 1s, N 1s and O 1s near edge x-ray absorption spectro-microscopy with a spectral resolution up to about 1:5000 and with STXM count rates in excess of 1 MHz.

Warwick, Tony; Ade, Harald; Kilcoyne, A.L. David; Kritscher, Michael; Tylisczcak, Tolek; Fakra, Sirine; Hitchcock, Adam P.; Hitchcock, Peter; Padmore, Howard A.

2001-12-12

402

Focused ion beam patterned Fe thin films A study by selective area Stokes polarimetry and soft x-Ray microscopy  

SciTech Connect

We demonstrate the potential to modify 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 chemical change to the 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, P. J.; Shen, T. H.; Grundy, P. J.; Im, M.-Y.; Fischer, P.; Morton, S. A.; Kilcoyne, A. L. D.

2010-11-14

403

Radiation background and beam quality in secondary X-ray imaging for human angiography with Au as contrast agent  

NASA Astrophysics Data System (ADS)

A calculation is carried out to assess the capabilities of Secondary X-ray Imaging (SXI). Human angiography is used as an example. An originally well focused primary photon pencil beam is rastered through the target (the human heart) in two dimensions. The signal consists of fluorescent photons from a contrast agent, registered by a wide angle (of order ? steradians) detector. The primary photons may be significantly more energetic than the signal photons. The last two features result in clearer images and a reduction of shadowing by obstructions inside the body. Sharp imaging is compatible with locally quantitative measurements, and with pixel-by-pixel elemental analysis. The detector need not be position sensitive. Most primary photons will be (predominantly Compton) scattered before they reach the target, the scattered photons form a broad halo around the unscattered primary beam, which remains sharp and well focused. To discriminate against scattered background, the photons have to pass through a position/momentum selector, a W Hf absorber shield, and a time window. The calculation gives the approximate energy spectrum for the scattered photons generated, for the photons passing through the position/momentum selector, and for those arriving at the far side of the absorber shield, the last two evaluated for various time windows in the 1000 167ps range. The surviving background will cause relative image intensity fluctuations of the order of a percent. The primary beam intensity required for SXI is comparable or less than the intensity needed for the usual K-edge subtraction (KES) imaging process. However, for SXI the primary photon energy spread may be one or two orders higher than needed for KES, thus relaxing the requirements on the primary photon source. If an undulator is used, monochromatization may not be needed. That further reduces cost and demands on the photon source, which may be a small low energy electron ring. To realize the full potential of the method (beyond that stated above), would require a new type of detector.

Csonka, Paul L.

2006-01-01

404

Noise reduction by projection direction dependent diffusion for low dose fan-beam x-ray computed tomography  

NASA Astrophysics Data System (ADS)

We propose a novel method to reduce the noise in fan-beam computed tomography (CT) imaging. First, the inverse Radon transform is induced for a family of differential expression of projection function. Second, the diffusion partial differential equation (PDE) is generalized from image space to projection space in parallel-beam geometry. Third, the diffusion PDE is further induced from parallel-beam geometry to fan-beam geometry. Finally, the projection direction dependent diffusion is developed to reduce CT noise, which arises from the quantum variation in the low dose exposure of a medical x-ray CT (XCT) system. The proposed noise reduction processes projections iteratively and dependently on x-ray path position, followed by a general CT reconstruction. Numerical simulation studies have demonstrated its feasibility in the noise reduction of low dose fan-beam XCT imaging.

Tang, Shaojie; Mou, Xuanqin; Zhang, Yanbo; Yu, Hengyong

2011-03-01

405

X-ray detection by direct modulation of an optical probe beam-Radsensor: Progress on development for imaging applications  

SciTech Connect

We present a progress report on our new x-ray detection technique based on optical measurement of the effects of x-ray absorption and electron hole pair creation in a direct band-gap semiconductor. The electron-hole pairs create a frequency dependent shift in optical refractive index and absorption. This is sensed by simultaneously directing an optical probe beam through the same volume of semiconducting medium that has experienced an x-ray induced modulation in the electron-hole population. If the wavelength of the optical probe beam is close to the semiconductor band-edge, the optical probe will be modulated significantly in phase and amplitude. We have analyzed the physics of the imaging radsensor, developed modeling tools for device design, and are cautiously optimistic that we will achieve single x-ray photon sensitivity, and picosecond response. These predictions will be tested with Cu K{alpha} xrays at the LLNL USP facility this spring and summer, with a cavity-based radsensor detector suitable for use in x-ray imagers.

Lowry, Mark E.; Bennett, Corey V.; Vernon, Stephen P.; Stewart, Richard; Welty, Rebecca J.; Heebner, John; Landen, Otto L.; Bell, Perry M. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States)

2004-10-01

406

3D-CT imaging using characteristic X-rays and visible lights produced by ion micro-beam bombardment  

NASA Astrophysics Data System (ADS)

We improved the spatial resolution of a 3D-CT imaging system consisting of a micro-beam and an X-ray CCD camera of 1 mega pixels (Hamamatsu photonics C8800X), whose element size is 8 ?m × 8 ?m providing an image size of 8 mm × 8 mm. A small ant of ˜6 mm body length was placed in a small tube, rotated by a stepping motor, and a spatial resolution of 4 ?m for X-ray micron-CT using characteristic Ti-K-X-rays (4.558 keV) produced by 3 MeV proton micro-beams was obtained. We applied the X-ray micron-CT to a small ant’s head and obtained the fine structures of the head’s interior. Because the CCD is sensitive to visible light, we also examined the capability of light micron-CT using visible red light from an Al2O3(Cr) ruby scintillator and applied the micron-CT to a small red tick. Though the red tick is highly transparent to Ti-K-X-rays, visible red light does not penetrate through the red tick. The most serious problem was dispersion of lights due to Thomson scattering resulting in obscure projection images.

Ishii, K.; Matsuyama, S.; Yamazaki, H.; Watanabe, Y.; Kawamura, Y.; Yamaguchi, T.; Momose, G.; Kikuchi, Y.; Terakawa, A.; Galster, W.

2006-08-01

407

X-ray and gamma-ray intensity measurements in 131I, 166Ho, 198Au and 199Au decays  

NASA Astrophysics Data System (ADS)

Relative intensities of X- and gamma rays emitted in the decays of 131I, 166Ho, 198Au and 199Au have been measured precisely using a set of five detectors: 96.0 cm3 and 57.1 cm3 coaxial HPGe detectors, a 28.27 mm2 × 5.0 mm vertical planar HPGe detector and two 28.27 mm2 × 5.5 mm Si(Li) detectors. The measured values of X-ray intensities are, in general, in good agreement with the theoretically calculated values. The intensities of different components of K and L X-rays in the above mentioned decays have been measured for the first time.

Chand, Bakhshish; Goswamy, Jatinder; Mehta, Devinder; Singh, Nirmal; Trehan, P. N.

1989-12-01

408

Optimization for Single-Spike X-Ray FELs at LCLS with a Low Charge Beam  

Microsoft Academic Search

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

Lanfa

2011-01-01

409

Tissue-Sparing Effect of X-ray Microplanar Beams Particulary in the CNS: Is a Bystander Effect Involved?  

SciTech Connect

Normal tissues, including the central nervous system, tolerate single exposures to narrow planes of synchrotron-generated x-rays (microplanar beams; microbeams) up to several hundred Gy. The repairs apparently involve the microvasculature and the glial system. We evaluate a hypothesis on the involvement of bystander effects in these repairs.

Dilmanian,A.; Qu, Y.; Feinendegen, L.; Pena, L.; Bacarian, T.; Henn, F.; Kalef-Ezra, J.; Liu, S.; Zhong, Z.; McDonald, J.

2007-01-01

410

Electron-beam-deposited Mo\\/Si and MoxSiy\\/Si multilayer x-ray mirrors and gratings  

Microsoft Academic Search

For the wavelength region above the Si-L edge normal incidence, soft x-ray mirrors are produced with peak reflectivities close to 60 percent. The multilayer systems consist of molybdenum and silicon and are fabricated by electron beam evaporation in ultrahigh vacuum. A smoothing of the boundaries, and thereby a drastic enhancement of the reflectivity, is obtained by thermal treatment of the

Bernt Schmiedeskamp; Andreas Kloidt; Hans-Juergen Stock; Ulf Kleineberg; Thorsten Doehring; Michael Proepper; Steffen Rahn; Kerstin Hilgers; Bernhard Heidemann; Thorsten Tappe; Ulrich Heinzmann; Michael K. Krumrey; Peter Mueller; Frank Scholze; Klaus F. Heidemann

1994-01-01

411

Methods for Assisting Recovery of Damaged Brain and Spinal Cord Using Arrays of X-Ray Microplanar Beams.  

National Technical Information Service (NTIS)

A method of assisting recovery of an injury site of brain or spinal cord injury includes providing a therapeutic dose of X-ray radiation to the injury site through an array of parallel microplanar beams. The dose at least temporarily removes regeneration ...

F. A. Dilmanian

2005-01-01

412

Damage characterization of SiN x-ray mask membrane caused by electron-beam exposure  

Microsoft Academic Search

The effects of exposure damage with an electron beam of 20 to 50 kV acceleration voltage on silicon nitride film prepared by LPCVD system have been investigated. It is shown that the optical and mechanical properties of this material are modified and may potentially limit the use as a membrane in an x-ray mask structure for the high density memory

Sang-Soo Choi; Young-Beom D. Jeon; Jong-Soo Kim; Hai Bin Chung; Sang-Yun Lee; Jong-Hyun Lee; Hyung-Joun Yoo

1996-01-01

413

High-Resolution X-Ray and Light Beam Induced Current (LBIC) Measuremnts of Multicrystalline Silicon Solar Cells.  

National Technical Information Service (NTIS)

High-resolution, spatially-resolved x-ray Laue patterns and high-resolution light beam induced current (LBIC) measurements are combined to study two multicrystalline solar cells made from the Heat Exchanger Method (HEM) and the Sting Ribbon Growth techniq...

A. Rohatgi C. E. Duty C. J. C. Bennett G. E. Jellison J. D. Budai J. Z. Tischler V. Yelundur

2010-01-01

414

A Monte Carlo approach for simulating the propagation of partially coherent x-ray beams  

NASA Astrophysics Data System (ADS)

Advances at SR sources in the generation of nanofocused beams with a high degree of transverse coherence call for effective techniques to simulate the propagation of partially coherent X-ray beams through complex optical systems in order to characterize how coherence properties such as the mutual coherence function (MCF) are propagated to the exit plane. Here we present an approach based on Monte Carlo sampling of the Green function. A Gauss-Shell Stochastic Source with arbitrary spatial coherence is synthesized by means of the Gaussian copula statistical tool. The Green function is obtained by sampling Huygens-Fresnel waves with Monte Carlo methods and is used to propagate each source realization to the detector plane. The sampling is implemented with a modified Monte Carlo ray tracing scheme where the optical path of each generated ray is stored. Such information is then used in the summation of the generated rays at the observation plane to account for coherence properties. This approach is used to simulate simple models of propagation in free space and with reflective and refractive optics.

Prodi, A.; Knudsen, E.; Willendrup, P.; Schmitt, S.; Ferrero, C.; Feidenhans'l, R.; Lefmann, Kim

2011-09-01

415

Parameterized algorithms for quantitative differentials in spectrally equivalent medical diagnostic x-ray beams  

SciTech Connect

Qualitative and quantitative equivalence of spectra transmitted by two different elemental filters require a good match in terms of shape and size over the entire energy range of 0-150 keV used in medical diagnostic radiology. However, the photoelectric absorptions and Compton scattering involved in the interaction of x rays with matter at these relatively low photon energies differ in a nonuniform manner with energy and atomic number. By careful choice of thicknesses for filter materials with an atomic number between 12 and 39, when compared with aluminum, it is possible to obtain transmitted beams of the same shape (quality) but not of the same size (quantity). In this paper, calculations have been carried out for the matching of the shapes and sizes of beams transmitted through specified thicknesses of aluminium filter and spectrally equivalent thicknesses of other filter materials (different from aluminium) using FORTRAN source codes traceable to the American Association of Physics in Medicine (AAPM), College Park, MD, USA. Parametrized algorithms for the evaluation of quantitative differentials (deficit or surplus) in radiation output (namely, photon fluence, exposure, kerma, energy imparted, absorbed dose, and effective dose) from these transmitted spectrally equivalent beams were developed. These differentials range between 1%, and 4% at 1 mm Al filtration and between 8%, and 25% for filtration of 6 mm Al for different filter materials in comparison with aluminum. Also developed were models for factors for converting measures of photon fluence, exposure-area product, (EAP), and kerma-area product (KAP) to risk related quantities such as energy imparted, absorbed dose, and effective dose from the spectrally equivalent beams. The thicknesses of other filter materials that are spectrally equivalent to given thicknesses of aluminum filter were characterized using polynomial functions. The fact that the use of equivalent spectra in radiological practice can provide means of ranking the differentials in radiographic image quality and stochastic risk is discussed.

Okunade, Akintunde Akangbe [Department of Physics, Obafemi Awolowo University, Ile-Ife, Osun State (Nigeria)

2005-06-15

416

Interlaced X-ray Microplanar Beams: A Radiosurgery Approach with Clinical Potential  

SciTech Connect

Studies have shown that x-rays delivered as arrays of parallel microplanar beams (microbeams), 25- to 90-{micro}m thick and spaced 100-300 {micro}m on-center, respectively, spare normal tissues including the central nervous system (CNS) and preferentially damage tumors. However, such thin microbeams can only be produced by synchrotron sources and have other practical limitations to clinical implementation. To approach this problem, we first studied CNS tolerance to much thicker beams. Three of four rats whose spinal cords were exposed transaxially to four 400-Gy, 0.68-mm microbeams, spaced 4 mm, and all four rats irradiated to their brains with large, 170-Gy arrays of such beams spaced 1.36 mm, all observed for 7 months, showed no paralysis or behavioral changes. We then used an interlacing geometry in which two such arrays at a 90 deg angle produced the equivalent of a contiguous beam in the target volume only. By using this approach, we produced 90-, 120-, and 150-Gy 3.4 x 3.4 x 3.4 mm3 exposures in the rat brain. MRIs performed 6 months later revealed focal damage within the target volume at the 120- and 150-Gy doses but no apparent damage elsewhere at 120 Gy. Monte Carlo calculations indicated a 30-{micro}{micro}m dose falloff (80-20%) at the edge of the target, which is much less than the 2- to 5-mm value for conventional radiotherapy and radiosurgery. These findings strongly suggest potential application of interlaced microbeams to treat tumors or to ablate nontumorous abnormalities with minimal damage to surrounding normal tissue.

Dilimanian,F.; Zhong, Z.; Bacarian, T.; Benveniste, H.; Romanelli, P.; Wang, R.; Welwart, J.; Yuasa, T.; Rosen, E.; Anschel, D.

2006-01-01

417

Operation of beam line facilities for real-time x-ray studies at Sector 7 of the advanced photon source. Final Report  

SciTech Connect

This Final Report documents the research accomplishments achieved in the first phase of operations of a new Advanced Photon Source beam line (7-ID MHATT-CAT) dedicated to real-time x-ray studies. The period covered by this report covers the establishment of a world-class facility for time-dependent x-ray studies of materials. During this period many new and innovative research programs were initiated at Sector 7 with support of this grant, most notably using a combination of ultrafast lasers and pulsed synchrotron radiation. This work initiated a new frontier of materials research: namely, the study of the dynamics of materials under extreme conditions of high intensity impulsive laser irradiation.

Clarke, Roy

2003-09-10

418

High-Resolution X-Ray and Light Beam Induced Current (LBIC) Measurements of Multcrystalline Silicon Solar Cells  

SciTech Connect

High-resolution, spatially-resolved x-ray Laue patterns and high-resolution light beam induced current (LBIC) measurements are combined to study two multicrystalline solar cells made from the Heat Exchanger Method (HEM) and the Sting Ribbon Growth technique. The LBIC measurements were made at 4 different wavelengths (488, 633, 780, and 980 nm), resulting in penetration depths ranging from <1 {mu}m to >100 {mu}m. There is a strong correlation between the x-ray and LBIC measurements, showing that some twins and grain boundaries are effective in the reduction of local quantum efficiency, while others are benign.

Jellison Jr, Gerald Earle [ORNL; Budai, John D [ORNL; Bennett, Charlee J C [ORNL; Tischler, Jonathan Zachary [ORNL; Duty, Chad E [ORNL; Yelundur, V. [Georgia Institute of Technology; Rohatgi, A. [Georgia Institute of Technology

2010-01-01

419

Effect of surface roughness on the spatial coherence of X-ray beams from third-generation synchrotron radiation sources.  

PubMed

The effect of the surface roughness of optical elements, such as Be windows and reflection mirrors, in synchrotron radiation beamlines on the spatial coherence of the X-ray beam is investigated systematically by means of digital simulation, in which a new model for X-ray reflection from a rough surface is proposed. A universal factor is employed to evaluate the spatial coherence quantitatively, based on which critical values for surface roughness are reached. The results from simulation are consistent with those from experiments. PMID:16609197

Wang, Y; Xiao, T; Xu, H

2000-07-01

420

Generating Ultrashort Coherent Soft X-Ray Radiation in Storage Rings Using Angular-Modulated Electron Beams  

SciTech Connect

A technique is proposed to generate ultrashort coherent soft x-ray radiation in storage rings using angular-modulated electron beams. In the scheme a laser operating in the TEM01 mode is first used to modulate the angular distribution of the electron beam in an undulator. After passing through a special beam line with nonzero transfer matrix element R{sub 54}, the angular modulation is converted to density modulation which contains considerable high harmonic components of the laser. It is found that the harmonic number can be 1 or 2 orders of magnitude higher than the standard coherent harmonic generation method which relies on beam energy modulation. The technique has the potential of generating femtosecond coherent soft x-ray radiation directly from an infrared seed laser and may open new research opportunities for ultrafast sciences in storage rings.

Xiang, D.; Wan, W. [SLAC National Accelerator Laboratory, Menlo Park, California, 94025 (United States); Lawrence Berkeley National Laboratory, Berkeley, California, 94720 (United States)

2010-02-26