High energy resolution and first time-dependent positron annihilation induced Auger electron spectroscopty

Energy Technology Data Exchange (ETDEWEB)

Mayer, Jakob

2010-04-03

It was the aim of this thesis to improve the existing positron annihilation induced Auger spectrometer at the highly intense positron source NEPOMUC (NEutron induced POsitron source MUniCh) in several ways: Firstly, the measurement time for a single spectrum should be reduced from typically 12 h to roughly 1 h or even less. Secondly, the energy resolution, which amounted to {delta}E/E{approx}10%, should be increased by at least one order of magnitude in order to make high resolution positron annihilation induced Auger spectroscopy (PAES)-measurements of Auger transitions possible and thus deliver more information about the nature of the Auger process. In order to achieve these objectives, the PAES spectrometer was equipped with a new electron energy analyzer. For its ideal operation all other components of the Auger analysis chamber had to be adapted. Particularly the sample manipulation and the positron beam guidance had to be renewed. Simulations with SIMION {sup registered} ensured the optimal positron lens parameters. After the adjustment of the new analyzer and its components, first measurements illustrated the improved performance of the PAES setup: Firstly, the measurement time for short overview measurements was reduced from 3 h to 420 s. The measurement time for more detailed Auger spectra was shortened from 12 h to 80 min. Secondly, even with the reduced measurement time, the signal to noise ratio was also enhanced by one order of magnitude. Finally, the energy resolution was improved to {delta}E/E < 1. The exceptional surface sensitivity and elemental selectivity of PAES was demonstrated in measurements of Pd and Fe, both coated with Cu layers of varying thickness. PAES showed that with 0.96 monolayer of Cu on Fe, more than 55% of the detected Auger electrons stem from Cu. In the case of the Cu coated Pd sample 0.96 monolayer of Cu resulted in a Cu Auger fraction of more than 30% with PAES and less than 5% with electron induced Auger spectroscopy

The effect of pattern overlap on the accuracy of high resolution electron backscatter diffraction measurements

Energy Technology Data Exchange (ETDEWEB)

Tong, Vivian, E-mail: v.tong13@imperial.ac.uk [Department of Materials, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Jiang, Jun [Department of Materials, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Wilkinson, Angus J. [Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH (United Kingdom); Britton, T. Ben [Department of Materials, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

2015-08-15

High resolution, cross-correlation-based, electron backscatter diffraction (EBSD) measures the variation of elastic strains and lattice rotations from a reference state. Regions near grain boundaries are often of interest but overlap of patterns from the two grains could reduce accuracy of the cross-correlation analysis. To explore this concern, patterns from the interior of two grains have been mixed to simulate the interaction volume crossing a grain boundary so that the effect on the accuracy of the cross correlation results can be tested. It was found that the accuracy of HR-EBSD strain measurements performed in a FEG-SEM on zirconium remains good until the incident beam is less than 18 nm from a grain boundary. A simulated microstructure was used to measure how often pattern overlap occurs at any given EBSD step size, and a simple relation was found linking the probability of overlap with step size. - Highlights: • Pattern overlap occurs at grain boundaries and reduces HR-EBSD accuracy. • A test is devised to measure the accuracy of HR-EBSD in the presence of overlap. • High pass filters can sometimes, but not generally, improve HR-EBSD measurements. • Accuracy of HR-EBSD remains high until the reference pattern intensity is <72%. • 9% of points near a grain boundary will have significant error for 200nm step size in Zircaloy-4.

High-resolution noise substitution to measure overfitting and validate resolution in 3D structure determination by single particle electron cryomicroscopy.

Science.gov (United States)

Chen, Shaoxia; McMullan, Greg; Faruqi, Abdul R; Murshudov, Garib N; Short, Judith M; Scheres, Sjors H W; Henderson, Richard

2013-12-01

Three-dimensional (3D) structure determination by single particle electron cryomicroscopy (cryoEM) involves the calculation of an initial 3D model, followed by extensive iterative improvement of the orientation determination of the individual particle images and the resulting 3D map. Because there is much more noise than signal at high resolution in the images, this creates the possibility of noise reinforcement in the 3D map, which can give a false impression of the resolution attained. The balance between signal and noise in the final map at its limiting resolution depends on the image processing procedure and is not easily predicted. There is a growing awareness in the cryoEM community of how to avoid such over-fitting and over-estimation of resolution. Equally, there has been a reluctance to use the two principal methods of avoidance because they give lower resolution estimates, which some people believe are too pessimistic. Here we describe a simple test that is compatible with any image processing protocol. The test allows measurement of the amount of signal and the amount of noise from overfitting that is present in the final 3D map. We have applied the method to two different sets of cryoEM images of the enzyme beta-galactosidase using several image processing packages. Our procedure involves substituting the Fourier components of the initial particle image stack beyond a chosen resolution by either the Fourier components from an adjacent area of background, or by simple randomisation of the phases of the particle structure factors. This substituted noise thus has the same spectral power distribution as the original data. Comparison of the Fourier Shell Correlation (FSC) plots from the 3D map obtained using the experimental data with that from the same data with high-resolution noise (HR-noise) substituted allows an unambiguous measurement of the amount of overfitting and an accompanying resolution assessment. A simple formula can be used to calculate an

Secondary electron spectroscopy and Auger microscopy at high spatial resolution. Application to scanning electron microscopy

International Nuclear Information System (INIS)

Le Gressus, Claude; Massignon, Daniel; Sopizet, Rene

1979-01-01

Secondary electron spectroscopy (SES), Auger electron spectroscopy (AES) and electron energy loss spectroscopy (ELS) are combined with ultra high vacuum scanning microscopy (SEM) for surface analysis at high spatial resolution. Reliability tests for the optical column for the vacuum and for the spectrometer are discussed. Furthermore the sensitivity threshold in AES which is compatible with a non destructive surface analysis at high spatial resolution is evaluated. This combination of all spectroscopies is used in the study of the beam damage correlated with the well known secondary electron image (SEI) darkening still observed in ultra high vacuum. The darkening is explained as a bulk decontamination of the sample rather than as a surface contamination from the residual vacuum gas [fr

Understanding deformation with high angular resolution electron backscatter diffraction (HR-EBSD)

Science.gov (United States)

Britton, T. B.; Hickey, J. L. R.

2018-01-01

High angular resolution electron backscatter diffraction (HR-EBSD) affords an increase in angular resolution, as compared to ‘conventional’ Hough transform based EBSD, of two orders of magnitude, enabling measurements of relative misorientations of 1 x 10-4 rads (~ 0.006°) and changes in (deviatoric) lattice strain with a precision of 1 x 10-4. This is achieved through direct comparison of two or more diffraction patterns using sophisticated cross-correlation based image analysis routines. Image shifts between zone axes in the two-correlated diffraction pattern are measured with sub-pixel precision and this realises the ability to measure changes in interplanar angles and lattice orientation with a high degree of sensitivity. These shifts are linked to strains and lattice rotations through simple geometry. In this manuscript, we outline the basis of the technique and two case studies that highlight its potential to tackle real materials science challenges, such as deformation patterning in polycrystalline alloys.

Dose-dependent high-resolution electron ptychography

International Nuclear Information System (INIS)

D'Alfonso, A. J.; Allen, L. J.; Sawada, H.; Kirkland, A. I.

2016-01-01

Recent reports of electron ptychography at atomic resolution have ushered in a new era of coherent diffractive imaging in the context of electron microscopy. We report and discuss electron ptychography under variable electron dose conditions, exploring the prospects of an approach which has considerable potential for imaging where low dose is needed

Refinement procedure for the image alignment in high-resolution electron tomography.

Science.gov (United States)

Houben, L; Bar Sadan, M

2011-01-01

High-resolution electron tomography from a tilt series of transmission electron microscopy images requires an accurate image alignment procedure in order to maximise the resolution of the tomogram. This is the case in particular for ultra-high resolution where even very small misalignments between individual images can dramatically reduce the fidelity of the resultant reconstruction. A tomographic-reconstruction based and marker-free method is proposed, which uses an iterative optimisation of the tomogram resolution. The method utilises a search algorithm that maximises the contrast in tomogram sub-volumes. Unlike conventional cross-correlation analysis it provides the required correlation over a large tilt angle separation and guarantees a consistent alignment of images for the full range of object tilt angles. An assessment based on experimental reconstructions shows that the marker-free procedure is competitive to the reference of marker-based procedures at lower resolution and yields sub-pixel accuracy even for simulated high-resolution data. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of a high-resolution electron-beam profile monitor using Fresnel zone plates

International Nuclear Information System (INIS)

Nakamura, Norio; Sakai, Hiroshi; Muto, Toshiya; Hayano, Hitoshi

2004-01-01

We present a high-resolution and real-time beam profile monitor using Fresnel zone plates (FZPs) developed in the KEK-ATF damping ring. The monitor system has an X-ray imaging optics with two FZPs. In this monitor, the synchrotron radiation from the electron beam at the bending magnet is monochromatized by a crystal monochromator and the transverse electron beam image is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. The expected spatial resolution for the selected photon energy of 3.235 keV is less than 1 μm. With the beam profile monitor, we succeeded in obtaining a clear electron-beam image and measuring the extremely small beam size less than 10 μm. It is greatly expected that the beam profile monitor will be used in high-brilliance light sources and low-emittance accelerators. (author)

High-resolution electron collision spectroscopy with multicharged ions in merged beams

Energy Technology Data Exchange (ETDEWEB)

Lestinsky, M.

2007-04-18

The Heidelberg ion storage ring Tsr is currently the only ring equipped with two independent devices for the collinear merging of a cold electron beam with stored ions. This greatly improves the potential of electron-ion collision experiments, as the ion beam can be cooled with one electron beam, while the other one is used as a dedicated target for energy-resolved electron collision processes, such as recombination. The work describes the implementation of this system for rst electron collision spectroscopy experiments. A detection system has been realized including an ion detector and specroscopic beam-control software and instrumentation. Moreover, in order to improve the spectroscopic resolution systematical studies of intrinsic relaxation processes in the electron beam have been carried out. These include the dependence on the electron beam density, the magnetic guiding eld strength, and the acceleration geometry. The recombination measurements on low-lying resonances in lithiumlike Sc{sup 18+} yield a high-precision measurement of the 2s-2p{sub 3/2} transition energy in this system. Operation of the two-electron-beam setup at high collision energy ({approx}1000 eV) is established using resonances of hydrogenlike Mg{sup 11+}, while the unique possibility of modifying the beam-merging geometry con rms its importance for the electron-ion recombination rate at lowest relative energy, as demonstrated on F{sup 6+}. (orig.)

High-resolution electron collision spectroscopy with multicharged ions in merged beams

International Nuclear Information System (INIS)

Lestinsky, M.

2007-01-01

The Heidelberg ion storage ring Tsr is currently the only ring equipped with two independent devices for the collinear merging of a cold electron beam with stored ions. This greatly improves the potential of electron-ion collision experiments, as the ion beam can be cooled with one electron beam, while the other one is used as a dedicated target for energy-resolved electron collision processes, such as recombination. The work describes the implementation of this system for rst electron collision spectroscopy experiments. A detection system has been realized including an ion detector and specroscopic beam-control software and instrumentation. Moreover, in order to improve the spectroscopic resolution systematical studies of intrinsic relaxation processes in the electron beam have been carried out. These include the dependence on the electron beam density, the magnetic guiding eld strength, and the acceleration geometry. The recombination measurements on low-lying resonances in lithiumlike Sc 18+ yield a high-precision measurement of the 2s-2p 3/2 transition energy in this system. Operation of the two-electron-beam setup at high collision energy (∼1000 eV) is established using resonances of hydrogenlike Mg 11+ , while the unique possibility of modifying the beam-merging geometry con rms its importance for the electron-ion recombination rate at lowest relative energy, as demonstrated on F 6+ . (orig.)

High-resolution observation by double-biprism electron holography

International Nuclear Information System (INIS)

Harada, Ken; Tonomura, Akira; Matsuda, Tsuyoshi; Akashi, Tetsuya; Togawa, Yoshihiko

2004-01-01

High-resolution electron holography has been achieved by using a double-biprism interferometer implemented on a 1 MV field emission electron microscope. The interferometer was installed behind the first magnifying lens to narrow carrier fringes and thus enabled complete separation of sideband Fourier spectrum from center band in reconstruction process. Holograms of Au fine particles and single-crystalline thin films with the finest fringe spacing of 4.2 pm were recorded and reconstructed. The overall holography system including the reconstruction process performed well for holograms in which carrier fringes had a spacing of around 10 pm. High-resolution lattice images of the amplitude and phase were clearly reconstructed without mixing of the center band and sideband information. Additionally, entire holograms were recorded without Fresnel fringes normally generated by the filament electrode of the biprism, and the holograms were thus reconstructed without the artifacts caused by Fresnel fringes

OTR profile measurement of a LINAC electron beam with portable ultra high-speed camera

International Nuclear Information System (INIS)

Mogi, T.; Nisiyama, S.; Tomioka, S.; Enoto, T.

2004-01-01

We have studied on and developed a portable ultra high-speed camera, and so applied to measurement of a LINAC electron beam. We measured spatial OTR profiles of a LINAC electron beam using this camera with temporal resolution 80ns. (author)

High spatial resolution upgrade of the electron cyclotron emission radiometer for the DIII-D tokamak.

Science.gov (United States)

Truong, D D; Austin, M E

2014-11-01

The 40-channel DIII-D electron cyclotron emission (ECE) radiometer provides measurements of Te(r,t) at the tokamak midplane from optically thick, second harmonic X-mode emission over a frequency range of 83-130 GHz. The frequency spacing of the radiometer's channels results in a spatial resolution of ∼1-3 cm, depending on local magnetic field and electron temperature. A new high resolution subsystem has been added to the DIII-D ECE radiometer to make sub-centimeter (0.6-0.8 cm) resolution Te measurements. The high resolution subsystem branches off from the regular channels' IF bands and consists of a microwave switch to toggle between IF bands, a switched filter bank for frequency selectivity, an adjustable local oscillator and mixer for further frequency down-conversion, and a set of eight microwave filters in the 2-4 GHz range. Higher spatial resolution is achieved through the use of a narrower (200 MHz) filter bandwidth and closer spacing between the filters' center frequencies (250 MHz). This configuration allows for full coverage of the 83-130 GHz frequency range in 2 GHz bands. Depending on the local magnetic field, this translates into a "zoomed-in" analysis of a ∼2-4 cm radial region. Expected uses of these channels include mapping the spatial dependence of Alfven eigenmodes, geodesic acoustic modes, and externally applied magnetic perturbations. Initial Te measurements, which demonstrate that the desired resolution is achieved, are presented.

Millisecond resolution electron fluxes from the Cluster satellites: Calibrated EDI ambient electron data

Science.gov (United States)

Förster, Matthias; Rashev, Mikhail; Haaland, Stein

2017-04-01

The Electron Drift Instrument (EDI) onboard Cluster can measure 500 eV and 1 keV electron fluxes with high time resolution during passive operation phases in its Ambient Electron (AE) mode. Data from this mode is available in the Cluster Science Archive since October 2004 with a cadence of 16 Hz in the normal mode or 128 Hz for burst mode telemetry intervals. The fluxes are recorded at pitch angles of 0, 90, and 180 degrees. This paper describes the calibration and validation of these measurements. The high resolution AE data allow precise temporal and spatial diagnostics of magnetospheric boundaries and will be used for case studies and statistical studies of low energy electron fluxes in the near-Earth space. We show examples of applications.

On the optical stability of high-resolution transmission electron microscopes

International Nuclear Information System (INIS)

Barthel, J.; Thust, A.

2013-01-01

In the recent two decades the technique of high-resolution transmission electron microscopy experienced an unprecedented progress through the introduction of hardware aberration correctors and by the improvement of the achievable resolution to the sub-Ångström level. The important aspect that aberration correction at a given resolution requires also a well defined amount of optical stability has received little attention so far. Therefore we investigate the qualification of a variety of high-resolution electron microscopes to maintain an aberration corrected optical state in terms of an optical lifetime. We develop a comprehensive statistical framework for the estimation of the optical lifetime and find remarkably low values between tens of seconds and a couple of minutes. Probability curves are introduced, which inform the operator about the chance to work still in the fully aberration corrected state. - Highlights: • We investigate the temporal stability of optical aberrations in HRTEM. • We develop a statistical framework for the estimation of optical lifetimes. • We introduce plots showing the success probability for aberration-free work. • Optical lifetimes in sub-Ångström electron microscopy are surprisingly low. • The success of aberration correction depends strongly on the optical stability

Practical considerations for high spatial and temporal resolution dynamic transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Armstrong, Michael R. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States)], E-mail: armstrong30@llnl.gov; Boyden, Ken [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Browning, Nigel D. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Department of Chemical Engineering and Materials Science, University of California-Davis, One Shields Avenue, Davis, CA 95616 (United States); Campbell, Geoffrey H.; Colvin, Jeffrey D.; De Hope, William J.; Frank, Alan M. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Gibson, David J.; Hartemann, Fred [N Division, Physics and Advanced Technologies Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-280, Livermore, CA 94550 (United States); Kim, Judy S. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States); Department of Chemical Engineering and Materials Science, University of California-Davis, One Shields Avenue, Davis, CA 95616 (United States); King, Wayne E.; La Grange, Thomas B.; Pyke, Ben J.; Reed, Bryan W.; Shuttlesworth, Richard M.; Stuart, Brent C.; Torralva, Ben R. [Materials Science and Technology Division, Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-356, Livermore, CA 94550 (United States)

2007-04-15

Although recent years have seen significant advances in the spatial resolution possible in the transmission electron microscope (TEM), the temporal resolution of most microscopes is limited to video rate at best. This lack of temporal resolution means that our understanding of dynamic processes in materials is extremely limited. High temporal resolution in the TEM can be achieved, however, by replacing the normal thermionic or field emission source with a photoemission source. In this case the temporal resolution is limited only by the ability to create a short pulse of photoexcited electrons in the source, and this can be as short as a few femtoseconds. The operation of the photo-emission source and the control of the subsequent pulse of electrons (containing as many as 5x10{sup 7} electrons) create significant challenges for a standard microscope column that is designed to operate with a single electron in the column at any one time. In this paper, the generation and control of electron pulses in the TEM to obtain a temporal resolution <10{sup -6} s will be described and the effect of the pulse duration and current density on the spatial resolution of the instrument will be examined. The potential of these levels of temporal and spatial resolution for the study of dynamic materials processes will also be discussed.

Practical considerations for high spatial and temporal resolution dynamic transmission electron microscopy

International Nuclear Information System (INIS)

Armstrong, Michael R.; Boyden, Ken; Browning, Nigel D.; Campbell, Geoffrey H.; Colvin, Jeffrey D.; De Hope, William J.; Frank, Alan M.; Gibson, David J.; Hartemann, Fred; Kim, Judy S.; King, Wayne E.; La Grange, Thomas B.; Pyke, Ben J.; Reed, Bryan W.; Shuttlesworth, Richard M.; Stuart, Brent C.; Torralva, Ben R.

2007-01-01

Although recent years have seen significant advances in the spatial resolution possible in the transmission electron microscope (TEM), the temporal resolution of most microscopes is limited to video rate at best. This lack of temporal resolution means that our understanding of dynamic processes in materials is extremely limited. High temporal resolution in the TEM can be achieved, however, by replacing the normal thermionic or field emission source with a photoemission source. In this case the temporal resolution is limited only by the ability to create a short pulse of photoexcited electrons in the source, and this can be as short as a few femtoseconds. The operation of the photo-emission source and the control of the subsequent pulse of electrons (containing as many as 5x10 7 electrons) create significant challenges for a standard microscope column that is designed to operate with a single electron in the column at any one time. In this paper, the generation and control of electron pulses in the TEM to obtain a temporal resolution -6 s will be described and the effect of the pulse duration and current density on the spatial resolution of the instrument will be examined. The potential of these levels of temporal and spatial resolution for the study of dynamic materials processes will also be discussed

High-resolution compact Johann crystal spectrometer with the Livermore electron beam ion trap

International Nuclear Information System (INIS)

Robbins, D.L.; Chen, H.; Beiersdorfer, P.; Faenov, A.Ya.; Pikuz, T.A.; May, M.J.; Dunn, J.; Smith, A.J.

2004-01-01

A compact high-resolution (λ/Δλ≅10 000) spherically bent crystal spectrometer in the Johann geometry was recently installed and tested on the Lawrence Livermore National Laboratory SuperEBIT electron beam ion trap. The curvature of the mica (002) crystal grating allows for higher collection efficiency compared to the flat and cylindrically bent crystal spectrometers commonly used on the Livermore electron beam ion traps. The spectrometer's Johann configuration enables orientation of its dispersion plane to be parallel to the electron beam propagation. Used in concert with a crystal spectrometer, whose dispersion plane is perpendicular to the electron beam propagation, the polarization of x-ray emission lines can be measured

High energy resolution and first time-dependent positron annihilation induced Auger electron spectroscopty

International Nuclear Information System (INIS)

Mayer, Jakob

2010-01-01

It was the aim of this thesis to improve the existing positron annihilation induced Auger spectrometer at the highly intense positron source NEPOMUC (NEutron induced POsitron source MUniCh) in several ways: Firstly, the measurement time for a single spectrum should be reduced from typically 12 h to roughly 1 h or even less. Secondly, the energy resolution, which amounted to ΔE/E∼10%, should be increased by at least one order of magnitude in order to make high resolution positron annihilation induced Auger spectroscopy (PAES)-measurements of Auger transitions possible and thus deliver more information about the nature of the Auger process. In order to achieve these objectives, the PAES spectrometer was equipped with a new electron energy analyzer. For its ideal operation all other components of the Auger analysis chamber had to be adapted. Particularly the sample manipulation and the positron beam guidance had to be renewed. Simulations with SIMION registered ensured the optimal positron lens parameters. After the adjustment of the new analyzer and its components, first measurements illustrated the improved performance of the PAES setup: Firstly, the measurement time for short overview measurements was reduced from 3 h to 420 s. The measurement time for more detailed Auger spectra was shortened from 12 h to 80 min. Secondly, even with the reduced measurement time, the signal to noise ratio was also enhanced by one order of magnitude. Finally, the energy resolution was improved to ΔE/E 2,3 VV-transition with PAES. Thus, within this thesis two objectives were achieved: Firstly, the PAES spectrometer was renewed and improved by at least one order of magnitude with respect to the signal to noise ratio, the measurement time and the energy resolution. Secondly, several measurements have been carried out, demonstrating the high performance of the spectrometer. Amongst them are first dynamic PAES measurements and a high resolution measurement of the CuM 2,3 VV

The measurement and calculation of the X-ray spatial resolution obtained in the analytical electron microscope

International Nuclear Information System (INIS)

Michael, J.R.; Williams, D.B.

1990-01-01

The X-ray microanalytical spatial resolution is determined experimentally in various analytical electron microscopes by measuring the degradation of an atomically discrete composition profile across an interphase interface in a thin-foil of Ni-Cr-Fe. The experimental spatial resolutions are then compared with calculated values. The calculated spatial resolutions are obtained by the mathematical convolution of the electron probe size with an assumed beam-broadening distribution and the single-scattering model of beam broadening. The probe size is measured directly from an image of the probe in a TEM/SETEM and indirectly from dark-field signal changes resulting from scanning the probe across the edge of an MgO crystal in a dedicated STEM. This study demonstrates the applicability of the convolution technique to the calculation of the microanalytical spatial resolution obtained in the analytical electron microscope. It is demonstrated that, contrary to popular opinion, the electron probe size has a major impact on the measured spatial resolution in foils < 150 nm thick. (author)

Quantitative measurement of mean inner potential and specimen thickness from high-resolution off-axis electron holograms of ultra-thin layered WSe{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Winkler, Florian, E-mail: f.winkler@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Tavabi, Amir H. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Gemeinschaftslabor für Elektronenmikroskopie (GFE), RWTH Aachen University, D-52074 Aachen (Germany); Duchamp, Martial [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C), Forschungszentrum Jülich, D-52425 Jülich (Germany); Peter Grünberg Institute 5 (PGI-5), Forschungszentrum Jülich, D-52425 Jülich (Germany); Yucelen, Emrah [FEI Company, Achtseweg Noord 5, Eindhoven 5600 KA (Netherlands); Borghardt, Sven; Kardynal, Beata E. [Peter Grünberg Institute 9 (PGI-9), Forschungszentrum Jülich, D-52425 Jülich (Germany); and others

2017-07-15

The phase and amplitude of the electron wavefunction that has passed through ultra-thin flakes of WSe{sub 2} is measured from high-resolution off-axis electron holograms. Both the experimental measurements and corresponding computer simulations are used to show that, as a result of dynamical diffraction, the spatially averaged phase does not increase linearly with specimen thickness close to an [001] zone axis orientation even when the specimen has a thickness of only a few layers. It is then not possible to infer the local specimen thickness of the WSe{sub 2} from either the phase or the amplitude alone. Instead, we show that the combined analysis of phase and amplitude from experimental measurements and simulations allows an accurate determination of the local specimen thickness. The relationship between phase and projected potential is shown to be approximately linear for extremely thin specimens that are tilted by several degrees in certain directions from the [001] zone axis. A knowledge of the specimen thickness then allows the electrostatic potential to be determined from the measured phase. By using this combined approach, we determine a value for the mean inner potential of WSe{sub 2} of 18.9±0.8 V, which is 12% lower than the value calculated from neutral atom scattering factors. - Highlights: • Quantitative analysis of high resolution electron holograms of WSe{sub 2}. • Local specimen thickness determination and estimation of tilt angle. • Mean inner potential evaluation of WSe2 avoiding dynamical diffraction.

Design and construction of a high-stability, low-noise power supply for use with high-resolution electron energy loss spectrometers

International Nuclear Information System (INIS)

Katz, J.E.; Davies, P.W.; Crowell, J.E.; Somorjai, G.A.

1982-01-01

The design and construction of a high-stability, low-noise power supply which provides potentials for the lens and analyzer elements of a 127 0 Ehrhardt-type high-resolution electron energy loss spectrometer (HREELS) is described. The supply incorporates a filament emission-control circuit and facilities for measuring electron beam current at each spectrometer element, thus facilitating optimal tuning of the spectrometer. Spectra obtained using this supply are shown to have a four-fold improvement in signal-to-noise ratio and a higher resolution of the vibrational loss features when compared with spectra taken using a previously existing supply based on passive potential divider networks

High spatial resolution upgrade of the electron cyclotron emission radiometer for the DIII-D tokamak

Energy Technology Data Exchange (ETDEWEB)

Truong, D. D., E-mail: dtruong@wisc.edu [Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Austin, M. E. [Institute for Fusion Studies, University of Texas, Austin, Texas, 78712 (United States)

2014-11-15

The 40-channel DIII-D electron cyclotron emission (ECE) radiometer provides measurements of T{sub e}(r,t) at the tokamak midplane from optically thick, second harmonic X-mode emission over a frequency range of 83–130 GHz. The frequency spacing of the radiometer's channels results in a spatial resolution of ∼1–3 cm, depending on local magnetic field and electron temperature. A new high resolution subsystem has been added to the DIII-D ECE radiometer to make sub-centimeter (0.6–0.8 cm) resolution T{sub e} measurements. The high resolution subsystem branches off from the regular channels’ IF bands and consists of a microwave switch to toggle between IF bands, a switched filter bank for frequency selectivity, an adjustable local oscillator and mixer for further frequency down-conversion, and a set of eight microwave filters in the 2–4 GHz range. Higher spatial resolution is achieved through the use of a narrower (200 MHz) filter bandwidth and closer spacing between the filters’ center frequencies (250 MHz). This configuration allows for full coverage of the 83–130 GHz frequency range in 2 GHz bands. Depending on the local magnetic field, this translates into a “zoomed-in” analysis of a ∼2–4 cm radial region. Expected uses of these channels include mapping the spatial dependence of Alfven eigenmodes, geodesic acoustic modes, and externally applied magnetic perturbations. Initial T{sub e} measurements, which demonstrate that the desired resolution is achieved, are presented.

Structure Identification in High-Resolution Transmission Electron Microscopic Images

DEFF Research Database (Denmark)

Vestergaard, Jacob Schack; Kling, Jens; Dahl, Anders Bjorholm

2014-01-01

A connection between microscopic structure and macroscopic properties is expected for almost all material systems. High-resolution transmission electron microscopy is a technique offering insight into the atomic structure, but the analysis of large image series can be time consuming. The present ...

Measuring the electron bunch timing with femtosecond resolution at FLASH

International Nuclear Information System (INIS)

Bock, Marie Kristin

2013-03-01

Bunch arrival time monitors (BAMs) are an integral part of the laser-based synchronisation system which is being developed at the Free Electron Laser in Hamburg (FLASH).The operation principle comprises the measurement of the electron bunch arrival time relative to the optical timing reference, which is provided by actively length-stabilised fibre-links of the synchronisation system. The monitors are foreseen to be used as a standard diagnostic tool, not only for FLASH but also for the future European X-Ray Free-Electron Laser (European XFEL). The present bunch arrival time monitors have evolved from proof-of-principle experiments to beneficial diagnostic devices, which are almost permanently available during standard machine operation. This achievement has been a major objective of this thesis. The developments went in parallel to improvements in the reliable and low-maintenance operation of the optical synchronisation system. The key topics of this thesis comprised the characterisation and optimisation of the opto-mechanical front-ends of both, the fibre-links and the BAMs. The extent of applications involving the bunch arrival time information has been enlarged, providing automated measurements for properties of the RF acceleration modules, for instance, the RF on-crest phase determination and the measurement of energy fluctuations. Furthermore, two of the currently installed BAMs are implemented in an active phase and gradient stabilisation of specific modules in order to minimise the arrival time jitter of the electron bunches at the location of the FEL undulators, which is crucial for a high timing resolution of pump-probe experiments.

Measuring the electron bunch timing with femtosecond resolution at FLASH

Energy Technology Data Exchange (ETDEWEB)

Bock, Marie Kristin

2013-03-15

Bunch arrival time monitors (BAMs) are an integral part of the laser-based synchronisation system which is being developed at the Free Electron Laser in Hamburg (FLASH).The operation principle comprises the measurement of the electron bunch arrival time relative to the optical timing reference, which is provided by actively length-stabilised fibre-links of the synchronisation system. The monitors are foreseen to be used as a standard diagnostic tool, not only for FLASH but also for the future European X-Ray Free-Electron Laser (European XFEL). The present bunch arrival time monitors have evolved from proof-of-principle experiments to beneficial diagnostic devices, which are almost permanently available during standard machine operation. This achievement has been a major objective of this thesis. The developments went in parallel to improvements in the reliable and low-maintenance operation of the optical synchronisation system. The key topics of this thesis comprised the characterisation and optimisation of the opto-mechanical front-ends of both, the fibre-links and the BAMs. The extent of applications involving the bunch arrival time information has been enlarged, providing automated measurements for properties of the RF acceleration modules, for instance, the RF on-crest phase determination and the measurement of energy fluctuations. Furthermore, two of the currently installed BAMs are implemented in an active phase and gradient stabilisation of specific modules in order to minimise the arrival time jitter of the electron bunches at the location of the FEL undulators, which is crucial for a high timing resolution of pump-probe experiments.

High-resolution EELS investigation of the electronic structure of ilmenites

NARCIS (Netherlands)

Radtke, G.; Lazar, S.; Botton, G.A.

2006-01-01

The electronic structure of a series of compounds belonging to the ilmenite family is investigated using high resolution electron energy loss spectroscopy (EELS). The energy loss near edge structure (ELNES) of the O-K, Ti-L23 and transition metal L23 edges have been recorded in MnTiO3, FeTiO3,

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

Science.gov (United States)

Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.; Neves, R. F. C.; Lopes, M. C. A.; de Oliveira, E. M.; da Costa, R. F.; Varella, M. T. do N.; Bettega, M. H. F.; Blanco, F.; García, G.; Lima, M. A. P.; Jones, D. B.

2015-10-01

The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5-10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

International Nuclear Information System (INIS)

Ferreira da Silva, F.; Lange, E.; Limão-Vieira, P.; Jones, N. C.; Hoffmann, S. V.; Hubin-Franskin, M.-J.; Delwiche, J.; Brunger, M. J.

2015-01-01

The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range

Electronic excitation of furfural as probed by high-resolution vacuum ultraviolet spectroscopy, electron energy loss spectroscopy, and ab initio calculations

Energy Technology Data Exchange (ETDEWEB)

Ferreira da Silva, F.; Lange, E. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Jones, N. C.; Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Århus C (Denmark); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Institut de Chimie-Bât. B6C, Université de Liège, B-4000 Liège 1 (Belgium); Brunger, M. J., E-mail: plimaovieira@fct.unl.pt, E-mail: michael.brunger@flinders.edu.au, E-mail: maplima@ifi.unicamp.br [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); and others

2015-10-14

The electronic spectroscopy of isolated furfural (2-furaldehyde) in the gas phase has been investigated using high-resolution photoabsorption spectroscopy in the 3.5–10.8 eV energy-range, with absolute cross section measurements derived. Electron energy loss spectra are also measured over a range of kinematical conditions. Those energy loss spectra are used to derive differential cross sections and in turn generalised oscillator strengths. These experiments are supported by ab initio calculations in order to assign the excited states of the neutral molecule. The good agreement between the theoretical results and the measurements allows us to provide the first quantitative assignment of the electronic state spectroscopy of furfural over an extended energy range.

High-resolution electron microscopy and its applications.

Science.gov (United States)

Li, F H

1987-12-01

A review of research on high-resolution electron microscopy (HREM) carried out at the Institute of Physics, the Chinese Academy of Sciences, is presented. Apart from the direct observation of crystal and quasicrystal defects for some alloys, oxides, minerals, etc., and the structure determination for some minute crystals, an approximate image-contrast theory named pseudo-weak-phase object approximation (PWPOA), which shows the image contrast change with crystal thickness, is described. Within the framework of PWPOA, the image contrast of lithium ions in the crystal of R-Li2Ti3O7 has been observed. The usefulness of diffraction analysis techniques such as the direct method and Patterson method in HREM is discussed. Image deconvolution and resolution enhancement for weak-phase objects by use of the direct method are illustrated. In addition, preliminary results of image restoration for thick crystals are given.

Construction of a high resolution electron beam profile monitor

International Nuclear Information System (INIS)

Norem, J.; Dawson, J.; Haberichter, W.; Novak, W.; Reed, L.; Yang, X.F.

1993-01-01

Bremsstrahlung from an electron beam on a heavy target can be used to image the beam profile using collimators and slits. The limiting resolution using this system is determined by Fresnel diffraction, and is ∼ √(λd/2), where λ is the photon wavelength and d is determined by the linear dimensions of the system. For linear colliders this resolution could be a few nm. The highest resolution requires detectors which see only high energy, (small λ), photons, and this is accomplished by converting photons to pairs, and detecting Cherenkov light in a nearly forward angle with a CCD detector or streak camera. Tests are planned at the Argonne APS and SLAC FFTB

An extended model of electrons: experimental evidence from high-resolution scanning tunneling microscopy

International Nuclear Information System (INIS)

Hofer, Werner A

2012-01-01

In a recent paper we introduced a model of extended electrons, which is fully compatible with quantum mechanics in the formulation of Schrödinger. However, it contradicts the current interpretation of electrons as point-particles. Here, we show by a statistical analysis of high-resolution scanning tunneling microscopy (STM) experiments, that the interpretation of electrons as point particles and, consequently, the interpretation of the density of electron charge as a statistical quantity will lead to a conflict with the Heisenberg uncertainty principle. Given the precision in these experiments we find that the uncertainty principle would be violated by close to two orders of magnitude, if this interpretation were correct. We are thus forced to conclude that the density of electron charge is a physically real, i.e. in principle precisely measurable quantity, as derived in a recent paper. Experimental evidence to the contrary, in particular high-energy scattering experiments, is briefly discussed. The finding is expected to have wide implications in condensed matter physics, chemistry, and biology, scientific disciplines which are based on the properties and interactions of electrons.

High-spatial-resolution electron density measurement by Langmuir probe for multi-point observations using tiny spacecraft

Science.gov (United States)

Hoang, H.; Røed, K.; Bekkeng, T. A.; Trondsen, E.; Clausen, L. B. N.; Miloch, W. J.; Moen, J. I.

2017-11-01

A method for evaluating electron density using a single fixed-bias Langmuir probe is presented. The technique allows for high-spatio-temporal resolution electron density measurements, which can be effectively carried out by tiny spacecraft for multi-point observations in the ionosphere. The results are compared with the multi-needle Langmuir probe system, which is a scientific instrument developed at the University of Oslo comprising four fixed-bias cylindrical probes that allow small-scale plasma density structures to be characterized in the ionosphere. The technique proposed in this paper can comply with the requirements of future small-sized spacecraft, where the cost-effectiveness, limited space available on the craft, low power consumption and capacity for data-links need to be addressed. The first experimental results in both the plasma laboratory and space confirm the efficiency of the new approach. Moreover, detailed analyses on two challenging issues when deploying the DC Langmuir probe on a tiny spacecraft, which are the limited conductive area of the spacecraft and probe surface contamination, are presented in the paper. It is demonstrated that the limited conductive area, depending on applications, can either be of no concern for the experiment or can be resolved by mitigation methods. Surface contamination has a small impact on the performance of the developed probe.

Sub-micron resolution selected area electron channeling patterns.

Science.gov (United States)

Guyon, J; Mansour, H; Gey, N; Crimp, M A; Chalal, S; Maloufi, N

2015-02-01

Collection of selected area channeling patterns (SACPs) on a high resolution FEG-SEM is essential to carry out quantitative electron channeling contrast imaging (ECCI) studies, as it facilitates accurate determination of the crystal plane normal with respect to the incident beam direction and thus allows control the electron channeling conditions. Unfortunately commercial SACP modes developed in the past were limited in spatial resolution and are often no longer offered. In this contribution we present a novel approach for collecting high resolution SACPs (HR-SACPs) developed on a Gemini column. This HR-SACP technique combines the first demonstrated sub-micron spatial resolution with high angular accuracy of about 0.1°, at a convenient working distance of 10mm. This innovative approach integrates the use of aperture alignment coils to rock the beam with a digitally calibrated beam shift procedure to ensure the rocking beam is maintained on a point of interest. Moreover a new methodology to accurately measure SACP spatial resolution is proposed. While column considerations limit the rocking angle to 4°, this range is adequate to index the HR-SACP in conjunction with the pattern simulated from the approximate orientation deduced by EBSD. This new technique facilitates Accurate ECCI (A-ECCI) studies from very fine grained and/or highly strained materials. It offers also new insights for developing HR-SACP modes on new generation high-resolution electron columns. Copyright © 2014 Elsevier B.V. All rights reserved.

High resolution surface scanning of Thick-GEM for single photo-electron detection

International Nuclear Information System (INIS)

Hamar, G.; Varga, D.

2012-01-01

An optical system for high resolution scanning of TGEM UV photon detection systems is introduced. The structure exploits the combination of a single Au-coated TGEM under study, and an asymmetric MWPC (Close Cathode Chamber) as post-amplification stage. A pulsed UV LED source with emission down to 240 nm has been focused to a spot of 0.07 mm on the TGEM surface, and single photo-electron charge spectra has been recorded over selected two dimensional regions. This way, the TGEM gain (order of 10–100) and TGEM photo-electron detection efficiency is clearly separated, unlike in case of continuous illumination. The surface structure connected to the TGEM photon detection is well observable, including inefficiencies in the holes and at the symmetry points between holes. The detection efficiency as well as the gas gain are fluctuating from hole to hole. The gain is constant in the hexagon around any hole, pointing to the fact that the gain depends on hole geometry, and less on the position where the electron enters. The detection probability map strongly changes with the field strength above the TGEM surface, in relation to the change of the actual surface field configuration. The results can be confronted with position-dependent simulations of TGEM electron transfer and gas multiplication. -- Highlights: ► First demonstration of Thick GEM surface scanning with single photo-electrons. ► Resolution of 0.1 mm is sufficient to identify structures connected to TGEM surface field structure. ► Gain and detection efficiency and separately measurable. ► Detection efficiency is high in a ring around the holes, and gain is constant in the hexagonal collection regions.

High-resolution x-ray scattering studies of charge ordering in highly correlated electron systems

International Nuclear Information System (INIS)

Ghazi, M.E.

2002-01-01

Many important properties of transition metal oxides such as, copper oxide high-temperature superconductivity and colossal magnetoresistance (CMR) in manganites are due to strong electron-electron interactions, and hence these systems are called highly correlated systems. These materials are characterised by the coexistence of different kinds of order, including charge, orbital, and magnetic moment. This thesis contains high-resolution X-ray scattering studies of charge ordering in such systems namely the high-T C copper oxides isostructural system, La 2-x Sr x NiO 4 with various Sr concentrations (x = 0.33 - 0.2), and the CMR manganite system, Nd 1/2 Sr 1/2 MnO 3 . It also includes a review of charge ordering in a large variety of transition metal oxides, such as ferrates, vanadates, cobaltates, nickelates, manganites, and cuprates systems, which have been reported to date in the scientific literature. Using high-resolution synchrotron X-ray scattering, it has been demonstrated that the charge stripes exist in a series of single crystals of La 2-x Sr x NiO 4 with Sr concentrations (x = 0.33 - 0.2) at low temperatures. Satellite reflections due to the charge ordering were found with the wavevector (2ε, 0, 1) below the charge ordering transition temperature, T CO , where 2ε is the amount of separation from the corresponding Bragg peak. The charge stripes are shown to be two-dimensional in nature both by measurements of their correlation lengths and by measurement of the critical exponents of the charge stripe melting transition with an anomaly at x = 0.25. The results show by decreasing the hole concentration from the x = 0.33 to 0.2, the well-correlated charge stripes change to a glassy state at x = 0.25. The electronic transition into the charge stripe phase is second-order without any corresponding structural transition. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. In a single-crystal of Nd

Measurement of few-electron uranium ions on a high-energy electron beam ion trap

International Nuclear Information System (INIS)

Beiersdorfer, P.

1994-01-01

The high-energy electron beam ion trap, dubbed Super-EBIT, was used to produce, trap, and excite uranium ions as highly charged as fully stripped U 92+ . The production of such highly charged ions was indicated by the x-ray emission observed with high-purity Ge detectors. Moreover, high-resolution Bragg crystal spectromters were used to analyze the x-ray emission, including a detailed measurement of both the 2s 1/2 -2p 3/2 electric dipole and 2p 1/2 -2p 3/2 magnetic dipole transitions. Unlike in ion accelerators, where the uranium ions move at relativistic speeds, the ions in this trap are stationary. Thus very precise measurements of the transition energies could be made, and the QED contribution to the transition energies could be measured within less than 1 %. Details of the production of these highly charged ions and their measurement is given

Impact of measuring electron tracks in high-resolution scientific charge-coupled devices within Compton imaging systems

International Nuclear Information System (INIS)

Chivers, D.H.; Coffer, A.; Plimley, B.; Vetter, K.

2011-01-01

We have implemented benchmarked models to determine the gain in sensitivity of electron-tracking based Compton imaging relative to conventional Compton imaging by the use of high-resolution scientific charge-coupled devices (CCD). These models are based on the recently demonstrated ability of electron-tracking based Compton imaging by using fully depleted scientific CCDs. Here we evaluate the gain in sensitivity by employing Monte Carlo simulations in combination with advanced charge transport models to calculate two-dimensional charge distributions corresponding to experimentally obtained tracks. In order to reconstruct the angle of the incident γ-ray, a trajectory determination algorithm was used on each track and integrated into a back-projection routine utilizing a geodesic-vertex ray tracing technique. Analysis was performed for incident γ-ray energies of 662 keV and results show an increase in sensitivity consistent with tracking of the Compton electron to approximately ±30 o .

Investigations and characterization of the microstructure of special ceramic materials using the high-resolution electron microscope

International Nuclear Information System (INIS)

Kirn, M.

1979-01-01

The possibilities to characterize phases and microstructures by direct lattice imaging are indicated in the following work. Ceramic materials are particularly suitable for this as these exhibit a high mechanical stability in the investigation in the transmission electron microscope. First of all the fundamentals of the high-resolution electron microscopy are introduced and the various resulting possibilities to characterize microstructures are presented. A report then follows on experimental observations on undisturbed crystals of special ceramics on a Si 3 N 4 basis. Furthermore, it is shown that the high-resolution electron microscope provides valuable contributions to the determination of structure, in particular of twin variants. Finally, revealing information on the structure of the interfaces was obtained with the help of high-resolution electron microscopy. (orig./IHOE) [de

Electron beam fabrication and characterization of high-resolution magnetic force microscopy tips

Science.gov (United States)

Rührig, M.; Porthun, S.; Lodder, J. C.; McVitie, S.; Heyderman, L. J.; Johnston, A. B.; Chapman, J. N.

1996-03-01

The stray field, magnetic microstructure, and switching behavior of high-resolution electron beam fabricated thin film tips for magnetic force microscopy (MFM) are investigated with different imaging modes in a transmission electron microscope (TEM). As the tiny smooth carbon needles covered with a thermally evaporated magnetic thin film are transparent to the electron energies used in these TEMs it is possible to observe both the external stray field emanating from the tips as well as their internal domain structure. The experiments confirm the basic features of electron beam fabricated thin film tips concluded from various MFM observations using these tips. Only a weak but highly concentrated stray field is observed emanating from the immediate apex region of the tip, consistent with their capability for high resolution. It also supports the negligible perturbation of the magnetization sample due to the tip stray field observed in MFM experiments. Investigation of the magnetization distributions within the tips, as well as preliminary magnetizing experiments, confirm a preferred single domain state of the high aspect ratio tips. To exclude artefacts of the observation techniques both nonmagnetic tips and those supporting different magnetization states are used for comparison.

Real-time database for high resolution neutron monitor measurements

Energy Technology Data Exchange (ETDEWEB)

Steigies, Christian T.; Rother, Oliver M.; Wimmer-Schweingruber, Robert F.; Heber, Bernd [IEAP, Christian-Albrechts-Universitaet zu Kiel (Germany)

2008-07-01

The worldwide network of standardised neutron monitors is, after 50 years, still the state-of-the-art instrumentation to measure spectral variations of the primary cosmic ray component. These measurements are an ideal complement to space based cosmic ray measurements. Data from the approximately 50 IGY and NM64 neutron monitors is stored locally but also available through data collections sites like the World Data Center (WDC) or the IZMIRAN ftp server. The data from the WDC is in a standard format, but only hourly values are available. IZMIRAN collects the data in the best available time resolution, but the data arrives on the ftp server only hours, sometimes days, after the measurements. Also, the high time-resolution measurements of the different stations do not have a common format, a conversion routine for each station is needed before they can be used for scientific analysis. Supported by the 7th framework program of the European Commission, we are setting up a real-time database where high resolution cosmic ray measurements will be stored and accessible immediately after the measurement. Stations that do not have 1-minute resolution measurements will be upgraded to 1-minute or better resolution with an affordable standard registration system, that will submit the measurements to the database via the internet in real-time.

High resolution surface scanning of Thick-GEM for single photo-electron detection

Energy Technology Data Exchange (ETDEWEB)

Hamar, G., E-mail: hamar.gergo@wigner.mta.hu [Wigner Research Centre for Physics, Budapest (Hungary); Varga, D., E-mail: vdezso@mail.cern.ch [Eoetvoes Lorand University, Budapest (Hungary)

2012-12-01

An optical system for high resolution scanning of TGEM UV photon detection systems is introduced. The structure exploits the combination of a single Au-coated TGEM under study, and an asymmetric MWPC (Close Cathode Chamber) as post-amplification stage. A pulsed UV LED source with emission down to 240 nm has been focused to a spot of 0.07 mm on the TGEM surface, and single photo-electron charge spectra has been recorded over selected two dimensional regions. This way, the TGEM gain (order of 10-100) and TGEM photo-electron detection efficiency is clearly separated, unlike in case of continuous illumination. The surface structure connected to the TGEM photon detection is well observable, including inefficiencies in the holes and at the symmetry points between holes. The detection efficiency as well as the gas gain are fluctuating from hole to hole. The gain is constant in the hexagon around any hole, pointing to the fact that the gain depends on hole geometry, and less on the position where the electron enters. The detection probability map strongly changes with the field strength above the TGEM surface, in relation to the change of the actual surface field configuration. The results can be confronted with position-dependent simulations of TGEM electron transfer and gas multiplication. -- Highlights: Black-Right-Pointing-Pointer First demonstration of Thick GEM surface scanning with single photo-electrons. Black-Right-Pointing-Pointer Resolution of 0.1 mm is sufficient to identify structures connected to TGEM surface field structure. Black-Right-Pointing-Pointer Gain and detection efficiency and separately measurable. Black-Right-Pointing-Pointer Detection efficiency is high in a ring around the holes, and gain is constant in the hexagonal collection regions.

A digital approach for real time high-rate high-resolution radiation measurements

International Nuclear Information System (INIS)

Gerardi, G.; Abbene, L.

2014-01-01

Modern spectrometers are currently developed by using digital pulse processing (DPP) systems, showing several advantages over traditional analog electronics. The aim of this work is to present digital strategies, in a time domain, for the development of real time high-rate high-resolution spectrometers. We propose a digital method, based on the single delay line (SDL) shaping technique, able to perform multi-parameter analysis with high performance even at high photon counting rates. A robust pulse shape and height analysis (PSHA), applied on single isolated time windows of the detector output waveforms, is presented. The potentialities of the proposed strategy are highlighted through both theoretical and experimental approaches. To strengthen our approach, the implementation of the method on a real-time system together with some experimental results are presented. X-ray spectra measurements with a semiconductor detector are performed both at low and high photon counting rates (up to 1.1 Mcps)

A digital approach for real time high-rate high-resolution radiation measurements

Energy Technology Data Exchange (ETDEWEB)

Gerardi, G.; Abbene, L., E-mail: leonardo.abbene@unipa.it

2014-12-21

Modern spectrometers are currently developed by using digital pulse processing (DPP) systems, showing several advantages over traditional analog electronics. The aim of this work is to present digital strategies, in a time domain, for the development of real time high-rate high-resolution spectrometers. We propose a digital method, based on the single delay line (SDL) shaping technique, able to perform multi-parameter analysis with high performance even at high photon counting rates. A robust pulse shape and height analysis (PSHA), applied on single isolated time windows of the detector output waveforms, is presented. The potentialities of the proposed strategy are highlighted through both theoretical and experimental approaches. To strengthen our approach, the implementation of the method on a real-time system together with some experimental results are presented. X-ray spectra measurements with a semiconductor detector are performed both at low and high photon counting rates (up to 1.1 Mcps)

Measurement of high-energy electrons by means of a Cherenkov detector in ISTTOK tokamak

Energy Technology Data Exchange (ETDEWEB)

Jakubowski, L., E-mail: lech.Jjakubowski@ipj.gov.p [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Zebrowski, J. [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Plyusnin, V.V. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049 - 001 Lisboa (Portugal); Malinowski, K.; Sadowski, M.J.; Rabinski, M. [Andrzej Soltan Institute for Nuclear Studies (IPJ), 05-400 Otwock-Swierk (Poland); Fernandes, H.; Silva, C.; Duarte, P. [Association Euratom/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av. Rovisco Pais, 1049 - 001 Lisboa (Portugal)

2010-10-15

The paper concerns detectors of the Cherenkov radiation which can be used to measure high-energy electrons escaping from short-living plasma. Such detectors have high temporal (about 1 ns) and spatial (about 1 mm) resolution. The paper describes a Cherenkov-type detector which was designed, manufactured and installed in the ISTTOK tokamak in order to measure fast runaway electrons. The radiator of that detector was made of an aluminium nitride (AlN) tablet with a light-tight filter on its front surface. Cherenkov signals from the radiator were transmitted through an optical cable to a fast photomultiplier. It made possible to perform direct measurements of the runaway electrons of energy above 80 keV. The measured energy values and spatial characteristics of the recorded electrons appeared to be consistent with results of numerical modelling of the runaway electron generation process in the ISTTOK tokamak.

High resolution electron attachment to molecules of atmospheric relevance

International Nuclear Information System (INIS)

Senn, G.

2000-10-01

This Ph.D. thesis is divided into three parts. The first is an introduction into the field of electron attachment. In the second part the experimental apparatus is described, and in the third part the results are presented. In the present thesis molecules were chosen for our investigations that are not only of academic interest but that also play an important role for applications or even the life on this planet. All the molecules studied in this work are of atmospheric relevance. NO, and OClO, are involved in the ozone depletion of the stratosphere. The D-layer of the ionosphere is an upper boundary of the ozone layer, therefore the interaction of the electrons from the D-layer with O 3 might play an important role for the chemistry in that part of the atmosphere. Especially the interaction of slow electrons (that will be present in the D-layer in large numbers) with ozone was emphasized in the present study. The production of O - and O 2 - by dissociative electron attachment to ozone was measured for incident electron energies between 0 and 10eV. A previously unobserved sharp structure was discovered in the formation of O - ions for electrons with zero kinetic energy. This additional cross section peak has important consequences for the role of ozone in the anion formation process in the ionosphere. Since OClO is a night time reservoir for chlorine atoms (Cl) and chlorine monoxide (ClO) both of which play a critical role in the depletion of the stratospheric ozone, we have studied negative ion formation following electron impact (0-10eV) to OClO. Despite its atmospheric relevance the mechanism of dissociative electron attachment (DEA) to NO is still a matter of controversy. DEA was studied at high energy resolution and with a kinetic-energy analysis of the O - fragment in two independent crossed electron-molecular-beam experiments. The DEA cross section exhibits a vertical onset near 7.45eV that corresponds to the energy threshold of the DEA channel O - ( 2 P

Spectral measurements of few-electron uranium ions produced and trapped in a high-energy electron beam ion trap

International Nuclear Information System (INIS)

Beiersdorfer, P.

1994-01-01

Measurements of 2s l/2 -2p 3/2 electric dipole and 2p 1/2 -2p 3/2 magnetic dipole and electric quadrupole transitions in U 82+ through U 89+ have been made with a high-resolution crystal spectrometer that recorded the line radiation from stationary ions produced and trapped in a high-energy electron beam ion trap. From the measurements we infer -39.21 ± 0.23 eV for the QED contribution to the 2s 1/2 -2p 3/2 transition energy of lithiumlike U 89+ . A comparison between our measurements and various computations illustrates the need for continued improvements in theoretical approaches for calculating the atomic structure of ions with two or more electrons in the L shell

New approach to 3-D, high sensitivity, high mass resolution space plasma composition measurements

International Nuclear Information System (INIS)

McComas, D.J.; Nordholt, J.E.

1990-01-01

This paper describes a new type of 3-D space plasma composition analyzer. The design combines high sensitivity, high mass resolution measurements with somewhat lower mass resolution but even higher sensitivity measurements in a single compact and robust design. While the lower resolution plasma measurements are achieved using conventional straight-through time-of-flight mass spectrometry, the high mass resolution measurements are made by timing ions reflected in a linear electric field (LEF), where the restoring force that an ion experiences is proportional to the depth it travels into the LEF region. Consequently, the ion's equation of motion in that dimension is that of a simple harmonic oscillator and its travel time is simply proportional to the square root of the ion's mass/charge (m/q). While in an ideal LEF, the m/q resolution can be arbitrarily high, in a real device the resolution is limited by the field linearity which can be achieved. In this paper we describe how a nearly linear field can be produced and discuss how the design can be optimized for various different plasma regimes and spacecraft configurations

Intense energetic electron flux enhancements in Mercury's magnetosphere: An integrated view with high-resolution observations from MESSENGER.

Science.gov (United States)

Baker, Daniel N; Dewey, Ryan M; Lawrence, David J; Goldsten, John O; Peplowski, Patrick N; Korth, Haje; Slavin, James A; Krimigis, Stamatios M; Anderson, Brian J; Ho, George C; McNutt, Ralph L; Raines, Jim M; Schriver, David; Solomon, Sean C

2016-03-01

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission to Mercury has provided a wealth of new data about energetic particle phenomena. With observations from MESSENGER's Energetic Particle Spectrometer, as well as data arising from energetic electrons recorded by the X-Ray Spectrometer and Gamma-Ray and Neutron Spectrometer (GRNS) instruments, recent work greatly extends our record of the acceleration, transport, and loss of energetic electrons at Mercury. The combined data sets include measurements from a few keV up to several hundred keV in electron kinetic energy and have permitted relatively good spatial and temporal resolution for many events. We focus here on the detailed nature of energetic electron bursts measured by the GRNS system, and we place these events in the context of solar wind and magnetospheric forcing at Mercury. Our examination of data at high temporal resolution (10 ms) during the period March 2013 through October 2014 supports strongly the view that energetic electrons are accelerated in the near-tail region of Mercury's magnetosphere and are subsequently "injected" onto closed magnetic field lines on the planetary nightside. The electrons populate the plasma sheet and drift rapidly eastward toward the dawn and prenoon sectors, at times executing multiple complete drifts around the planet to form "quasi-trapped" populations.

THE HIGH-RESOLUTION EXTREME-ULTRAVIOLET SPECTRUM OF N{sub 2} BY ELECTRON IMPACT

Energy Technology Data Exchange (ETDEWEB)

Heays, A. N. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Ajello, J. M.; Aguilar, A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Lewis, B. R.; Gibson, S. T., E-mail: heays@strw.leidenuniv.nl [Research School of Physics and Engineering, The Australian National University, Canberra, ACT 0200 (Australia)

2014-04-01

We have analyzed high-resolution (FWHM = 0.2 Å) extreme-ultraviolet (EUV, 800-1350 Å) laboratory emission spectra of molecular nitrogen excited by an electron impact at 20 and 100 eV under (mostly) optically thin, single-scattering experimental conditions. A total of 491 emission features were observed from N{sub 2} electronic-vibrational transitions and atomic N I and N II multiplets and their emission cross sections were measured. Molecular emission was observed at vibrationally excited ground-state levels as high as v'' = 17, from the a {sup 1}Π {sub g} , b {sup 1}Π {sub u} , and b'{sup 1}Σ {sub u} {sup +} excited valence states and the Rydberg series c'{sub n} {sub +1} {sup 1}Σ {sub u} {sup +}, c{sub n} {sup 1}Π {sub u} , and o{sub n} {sup 1}Π {sub u} for n between 3 and 9. The frequently blended molecular emission bands were disentangled with the aid of a sophisticated and predictive quantum-mechanical model of excited states that includes the strong coupling between valence and Rydberg electronic states and the effects of predissociation. Improved model parameters describing electronic transition moments were obtained from the experiment and allowed for a reliable prediction of the vibrationally summed electronic emission cross section, including an extrapolation to unobserved emission bands and those that are optically thick in the experimental spectra. Vibrationally dependent electronic excitation functions were inferred from a comparison of emission features following 20 and 100 eV electron-impact collisional excitation. The electron-impact-induced fluorescence measurements are compared with Cassini Ultraviolet Imaging Spectrograph observations of emissions from Titan's upper atmosphere.

Atomic-resolution transmission electron microscopy of electron beam–sensitive crystalline materials

Science.gov (United States)

Zhang, Daliang; Zhu, Yihan; Liu, Lingmei; Ying, Xiangrong; Hsiung, Chia-En; Sougrat, Rachid; Li, Kun; Han, Yu

2018-02-01

High-resolution imaging of electron beam–sensitive materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with extremely low beam doses, the time-constrained search for crystal zone axes, the precise image alignment, and the accurate determination of the defocus value. We develop a suite of methods to fulfill these requirements and acquire atomic-resolution TEM images of several metal organic frameworks that are generally recognized as highly sensitive to electron beams. The high image resolution allows us to identify individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers. We also apply our methods to other electron beam–sensitive materials, including the organic-inorganic hybrid perovskite CH3NH3PbBr3.

Atomic-resolution transmission electron microscopy of electron beam–sensitive crystalline materials

KAUST Repository

Zhang, Daliang

2018-01-18

High-resolution imaging of electron beam-sensitive materials is one of the most difficult applications of transmission electron microscopy (TEM). The challenges are manifold, including the acquisition of images with extremely low beam doses, the time-constrained search for crystal zone axes, the precise image alignment, and the accurate determination of the defocus value. We develop a suite of methods to fulfill these requirements and acquire atomic-resolution TEM images of several metal organic frameworks that are generally recognized as highly sensitive to electron beams. The high image resolution allows us to identify individual metal atomic columns, various types of surface termination, and benzene rings in the organic linkers. We also apply our methods to other electron beam–sensitive materials, including the organic-inorganic hybrid perovskite CH3NH3PbBr3.

Precision crystal alignment for high-resolution electron microscope imaging

International Nuclear Information System (INIS)

Wood, G.J.; Beeching, M.J.

1990-01-01

One of the more difficult tasks involved in obtaining quality high-resolution electron micrographs is the precise alignment of a specimen into the required zone. The current accepted procedure, which involves changing to diffraction mode and searching for symmetric point diffraction pattern, is insensitive to small amounts of misalignment and at best qualitative. On-line analysis of the fourier space representation of the image, both for determining and correcting crystal tilt, is investigated. 8 refs., 42 figs

High-resolution energetic particle measurements at 6.6R/sub E/ 3. Low-energy electron anisotropies and short-term substorm predictions

International Nuclear Information System (INIS)

Baker, D.N.; Higbie, P.R.; Hones, E.W. Jr.; Belian, R.D.

1978-01-01

Multiple detectors giving nearly complete 4π coverage of particle pitch angle distributions have provided high resolution measurements (in energy and time) of 30- to 300-keV electrons. Data from a spacecraft (1976-059A) in geostationary orbit show a remarkably consistent sequence of variations of the electron anisotropy before and during magnetospheric substorms. For periods typically 1--2 hours prior to the onset of substorms, electron distributions, peaked along the direction of the local magnetic field, are observed in the premidnight sector. These cigarlike anisotropies are accompanied by a local taillike magnetic field which may develop further during the event. At substorm onset an abrupt transition usually occurs from the cigar-shaped distributions to pancake-shaped distributions. This anisotropy sequence may be due to the buildup and subsequent release of stresses in the magnetotail; the cigar phase may also be due to associated processes at the dayside magnetopause causing a loss of 90 0 pitch angle particles. The present observations, based on approx.100 events, appear to provide a predictive tool for assessing the probability of occurrence of a substorm

High resolution transmission electron microscopy and microdiffraction for radiation damage analysis

International Nuclear Information System (INIS)

Sinclair, R.

1982-01-01

High resolution TEM techniques have developed to quite a sophisticated level over the past few years. In addition TEM instruments with a scanning capability have become available commercially which permit in particular the formation of a small electron probe at the specimen. Thus direct resolution and microdiffraction investigations of thin specimens are now possible, neither of which have been employed to any great extent in the analysis of radiation damage. Some recent advances which are thought to be relevant to this specific area of research are highlighted

High resolution and high voltage electron microscopy at the University of California, Berkeley

International Nuclear Information System (INIS)

Thomas, G.; Westmacott, K.H.

1978-01-01

Recent applications of high-resolution and high-voltage techniques at Berkely are described, using 100-kV TEMs and a standard 650-keV HVEM: grain boundary precipitation in Al--Zn, lattice imaging of grain boundaries in ceramics, steels, phase transitions and magnetic properties of ferrites, lattice defects, precipitation in Al--Si and behavior of interstitial dislocations under electron irradiation, effect of oxide films on loop formation in Al--Mg, and polytypism in magnesium Sialon. 13 refs. 12 figs

Electron energy-loss spectrometry at the frontier of spatial and energy resolution

International Nuclear Information System (INIS)

Hofer, F.; Grogger, W.; Kothleitner, G.

2004-01-01

Full text: Electron energy-loss spectroscopy (EELS) in the transmission electron microscope (TEM) is now used routinely as a means of measuring chemical and structural properties of very small regions of a thin specimen. The power of this technique depends significantly on two parameters: its spatial resolution and the energy resolution available in the spectrum and in the energy-filtered TEM (EFTEM) image. The cold field emission source and the Schottky emitter have made an energy resolution below 1 eV possible and it is now feasible to obtain data with a spatial resolution close to atomic dimensions, given the right instrumentation and specimen. EFTEM allows to record elemental maps at sub-nanometre resolution, being mainly limited by chromatic and spherical aberration of the objective lens and by delocalization of inelastic scattering. Recently the possibility of correcting spherical and even chromatic aberrations of electron lenses has become a practical reality thus improving the point resolution of the TEM to below 0.1 nm. The other limiting factor for EFTEM resolution is delocalization. However, recent measurements show that resolution values in the range of 1 nm and below can be achieved, even for energy-losses of only a few eV. In terms of energy-resolution, EELS and EFTEM compare less favourably with other spectroscopies. For common TEMs, the overall energy-resolution is mainly determined by the energy width of the electron source, typically between 0.5 and 1.5 eV. For comparison, synchrotron x-ray sources and beam line spectrometers, provide a resolution well below 0.1 eV for absorption spectroscopy. During the early sixties, the energy spread of an electron beam could be reduced by incorporating an energy-filter into the illumination system, but the system lacked spatial resolution. Later developments combined high energy resolution in the range of 0.1 eV with improved spatial resolution. Recently, FEI introduced a new high resolution EELS system based

Ultrastable gold substrates: Properties of a support for high-resolution electron cryomicroscopy of biological specimens

Science.gov (United States)

Russo, Christopher J.; Passmore, Lori A.

2016-01-01

Electron cryomicroscopy (cryo-EM) allows structure determination of a wide range of biological molecules and specimens. All-gold supports improve cryo-EM images by reducing radiation-induced motion and image blurring. Here we compare the mechanical and electrical properties of all-gold supports to amorphous carbon foils. Gold supports are more conductive, and have suspended foils that are not compressed by differential contraction when cooled to liquid nitrogen temperatures. These measurements show how the choice of support material and geometry can reduce specimen movement by more than an order of magnitude during low-dose imaging. We provide methods for fabrication of all-gold supports and preparation of vitrified specimens. We also analyse illumination geometry for optimal collection of high resolution, low-dose data. Together, the support structures and methods herein can improve the resolution and quality of images from any electron cryomicroscope. PMID:26592474

High resolution electron microscopy and electron diffraction of YBa2Cu3O(7-x)

International Nuclear Information System (INIS)

Krakow, W.; Shaw, T.M.

1988-01-01

Experimental high resolution electron micrographs and computer simulation experiments have been used to evaluate the visibility of the atomic constituents of YBa 2 Cu 3 O(7-x). In practice, the detection of oxygen has not been possible in contradiction to that predicted by modelling of perfect crystalline material. Preliminary computer experiments of the electron diffraction patterns when oxygen vacancies are introduced on the Cu-O sheets separating Ba layers show the diffuse streaks characteristic of short range ordering. 7 references

Design and performance of a spin-polarized electron energy loss spectrometer with high momentum resolution

Energy Technology Data Exchange (ETDEWEB)

Vasilyev, D.; Kirschner, J. [Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

2016-08-15

We describe a new “complete” spin-polarized electron energy loss spectrometer comprising a spin-polarized primary electron source, an imaging electron analyzer, and a spin analyzer of the “spin-polarizing mirror” type. Unlike previous instruments, we have a high momentum resolution of less than 0.04 Å{sup −1}, at an energy resolution of 90-130 meV. Unlike all previous studies which reported rather broad featureless data in both energy and angle dependence, we find richly structured spectra depending sensitively on small changes of the primary energy, the kinetic energy after scattering, and of the angle of incidence. The key factor is the momentum resolution.

High resolution measurements and modeling of auroral hydrogen emission line profiles

Directory of Open Access Journals (Sweden)

B. S. Lanchester

Full Text Available Measurements in the visible wavelength range at high spectral resolution (1.3 Å have been made at Longyearbyen, Svalbard (15.8 E,78.2 N during an interval of intense proton precipitation. The shape and Doppler shift of hydrogen Balmer beta line profiles have been compared with model line profiles, using as input ion energy spectra from almost coincident passes of the FAST and DMSP spacecraft. The comparison shows that the simulation contains the important physical processes that produce the profiles, and confirms that measured changes in the shape and peak wave-length of the hydrogen profiles are the result of changing energy input. This combination of high resolution measurements with modeling provides a method of estimating the incoming energy and changes in flux of precipitating protons over Svalbard, for given energy and pitch-angle distributions. Whereas for electron precipitation, information on the incident particles is derived from brightness and brightness ratios which require at least two spectral windows, for proton precipitation the Doppler profile of resulting hydrogen emission is directly related to the energy and energy flux of the incident energetic protons and can be used to gather information about the source region. As well as the expected Doppler shift to shorter wavelengths, the measured profiles have a significant red-shifted component, the result of upward flowing emitting hydrogen atoms.

Key words. Ionosphere (auroral ionosphere; particle precipitation – Magnetospheric physics (auroral phenomena

High resolution measurements and modeling of auroral hydrogen emission line profiles

Directory of Open Access Journals (Sweden)

B. S. Lanchester

2003-07-01

Full Text Available Measurements in the visible wavelength range at high spectral resolution (1.3 Å have been made at Longyearbyen, Svalbard (15.8 E,78.2 N during an interval of intense proton precipitation. The shape and Doppler shift of hydrogen Balmer beta line profiles have been compared with model line profiles, using as input ion energy spectra from almost coincident passes of the FAST and DMSP spacecraft. The comparison shows that the simulation contains the important physical processes that produce the profiles, and confirms that measured changes in the shape and peak wave-length of the hydrogen profiles are the result of changing energy input. This combination of high resolution measurements with modeling provides a method of estimating the incoming energy and changes in flux of precipitating protons over Svalbard, for given energy and pitch-angle distributions. Whereas for electron precipitation, information on the incident particles is derived from brightness and brightness ratios which require at least two spectral windows, for proton precipitation the Doppler profile of resulting hydrogen emission is directly related to the energy and energy flux of the incident energetic protons and can be used to gather information about the source region. As well as the expected Doppler shift to shorter wavelengths, the measured profiles have a significant red-shifted component, the result of upward flowing emitting hydrogen atoms.Key words. Ionosphere (auroral ionosphere; particle precipitation – Magnetospheric physics (auroral phenomena

Study of spatial resolution of coordinate detectors based on Gas Electron Multipliers

Science.gov (United States)

Kudryavtsev, V. N.; Maltsev, T. V.; Shekhtman, L. I.

2017-02-01

Spatial resolution of GEM-based tracking detectors is determined in the simulation and measured in the experiments. The simulation includes GEANT4 implemented transport of high energy electrons with careful accounting of atomic relaxation processes including emission of fluorescent photons and Auger electrons and custom post-processing with accounting of diffusion, gas amplification fluctuations, distribution of signals on readout electrodes, electronics noise and particular algorithm of final coordinate calculation (center of gravity). The simulation demonstrates that the minimum of spatial resolution of about 10 μm can be achieved with a gas mixture of Ar -CO2 (75-25 %) at a strips pitch from 250 μm to 300 μm. At a larger pitch the resolution quickly degrades reaching 80-100 μm at a pitch of 460-500 μm. Spatial resolution of low-material triple-GEM detectors for the DEUTERON facility at the VEPP-3 storage ring is measured at the extracted beam facility of the VEPP-4 M collider. One-coordinate resolution of the DEUTERON detector is measured with electron beam of 500 MeV, 1 GeV and 3.5 GeV energies. The determined value of spatial resolution varies in the range from approximately 35 μm to 50 μm for orthogonal tracks in the experiments.

Practical Approaches to Mitigation of Specimen Charging in High-Resolution Transmission Electron Microscopy

Directory of Open Access Journals (Sweden)

Young-Min Kim

2010-09-01

Full Text Available Specimen charging that is associated with the electron bombardment on the sample is a practical hindrance to high-resolution transmission electron microscopy (HRTEM analysis because it causes a severe loss of resolution in either diffraction or image data. Conductive thin film deposition on an insulating specimen has been proposed as an effective approach to the mitigation of the specimen charging; however, this method is generally not useful in HRTEM imaging of materials because the deposited film induces another artifact in the HRTEM image contrast. In this study, we propose practical methods to mitigate the specimen charging that takes place during the HRTEM of materials. For bulk-type specimens prepared by either an ion-thinning or focused-ion beam (FIB process, a plasma cleaning treatment is significantly effective in eliminating the charging phenomenon. In the case of low-dimensional nanomaterials such as nanowires and nanoparticles, the plasma cleaning is not feasible; however, the charging effect can be effectively eliminated by adjusting the electron illumination condition. The proposed methods facilitate a decrease in the buildup of specimen charging, thereby enhancing the quality of high-resolution images significantly.

High-resolution monochromated electron energy-loss spectroscopy of organic photovoltaic materials.

Science.gov (United States)

Alexander, Jessica A; Scheltens, Frank J; Drummy, Lawrence F; Durstock, Michael F; Hage, Fredrik S; Ramasse, Quentin M; McComb, David W

2017-09-01

Advances in electron monochromator technology are providing opportunities for high energy resolution (10 - 200meV) electron energy-loss spectroscopy (EELS) to be performed in the scanning transmission electron microscope (STEM). The energy-loss near-edge structure in core-loss spectroscopy is often limited by core-hole lifetimes rather than the energy spread of the incident illumination. However, in the valence-loss region, the reduced width of the zero loss peak makes it possible to resolve clearly and unambiguously spectral features at very low energy-losses (photovoltaics (OPVs): poly(3-hexlythiophene) (P3HT), [6,6] phenyl-C 61 butyric acid methyl ester (PCBM), copper phthalocyanine (CuPc), and fullerene (C 60 ). Data was collected on two different monochromated instruments - a Nion UltraSTEM 100 MC 'HERMES' and a FEI Titan 3 60-300 Image-Corrected S/TEM - using energy resolutions (as defined by the zero loss peak full-width at half-maximum) of 35meV and 175meV, respectively. The data was acquired to allow deconvolution of plural scattering, and Kramers-Kronig analysis was utilized to extract the complex dielectric functions. The real and imaginary parts of the complex dielectric functions obtained from the two instruments were compared to evaluate if the enhanced resolution in the Nion provides new opto-electronic information for these organic materials. The differences between the spectra are discussed, and the implications for STEM-EELS studies of advanced materials are considered. Copyright © 2017 Elsevier B.V. All rights reserved.

Efficient creation of electron vortex beams for high resolution STEM imaging.

Science.gov (United States)

Béché, A; Juchtmans, R; Verbeeck, J

2017-07-01

The recent discovery of electron vortex beams carrying quantised angular momentum in the TEM has led to an active field of research, exploring a variety of potential applications including the possibility of mapping magnetic states at the atomic scale. A prerequisite for this is the availability of atomic sized electron vortex beams at high beam current and mode purity. In this paper we present recent progress showing that by making use of the Aharonov-Bohm effect near the tip of a long single domain ferromagnetic Nickel needle, a very efficient aperture for the production of electron vortex beams can be realised. The aperture transmits more than 99% of all electrons and provides a vortex mode purity of up to 92%. Placing this aperture in the condenser plane of a state of the art Cs corrected microscope allows us to demonstrate atomic resolution HAADF STEM images with spatial resolution better than 1 Angström, in agreement with theoretical expectations and only slightly inferior to the performance of a non-vortex probe on the same instrument. Copyright © 2016 Elsevier B.V. All rights reserved.

High-resolution multi-slice PET

International Nuclear Information System (INIS)

Yasillo, N.J.; Chintu Chen; Ordonez, C.E.; Kapp, O.H.; Sosnowski, J.; Beck, R.N.

1992-01-01

This report evaluates the progress to test the feasibility and to initiate the design of a high resolution multi-slice PET system. The following specific areas were evaluated: detector development and testing; electronics configuration and design; mechanical design; and system simulation. The design and construction of a multiple-slice, high-resolution positron tomograph will provide substantial improvements in the accuracy and reproducibility of measurements of the distribution of activity concentrations in the brain. The range of functional brain research and our understanding of local brain function will be greatly extended when the development of this instrumentation is completed

High temperature and high resolution uv photoelectron spectroscopy using supersonic molecular beams

International Nuclear Information System (INIS)

Wang, Lai-Sheng; Reutt-Robey, J.E.; Niu, B.; Lee, Y.T.; Shirley, D.A.

1989-07-01

A high temperature molecular beam source with electron bombardment heating has been built for high resolution photoelectron spectroscopic studies of high temperature species and clusters. This source has the advantages of: producing an intense, continuous, seeded molecular beam, eliminating the interference of the heating mechanism from the photoelectron measurement. Coupling the source with our hemispherical electron energy analyzer, we can obtain very high resolution HeIα (584 angstrom) photoelectron spectra of high temperature species. Vibrationally-resolved photoelectron spectra of PbSe, As 2 , As 4 , and ZnCl 2 are shown to demonstrate the performance of the new source. 25 refs., 8 figs., 1 tab

High-effective position time spectrometer in actual measurements of low intensity region of electron spectra

International Nuclear Information System (INIS)

Babenkov, M.I.; Zhdanov, V.S.

2002-01-01

Magnetic position-time spectrometer was proposed in previous work, where not only electron coordinates in focal plane are measured by position sensitive detector (PSD) but places of their birth in beta source plane of a large area are fixed using another PSD, situated behind it, by quick effects, accompanying radioactive decay. PSD on the basis of macro-channel plates are used. It is succeeded in position-time spectrometer to combine beta sources of a large area with multichannel registration for a wide energy interval, that efficiency of measurements was two orders of magnitude increase d in comparison magnetic apparatus having PSD only in focal plane. Owing to two detectors' switching on coincidence the relation effect/background in increased minimum on two orders of magnitude in comparison with the same apparatus. At some complication of mathematical analysis it was obtained, that high characteristics of position-time spectrometer are kept during the use the magnetic field, providing double focusing. Owning to this focusing the gain the efficiency of measurements will make one more order of magnitude. Presented high-effective position-time spectrometer is supposed to use in the measurements of low-intensity region of electron spectra, which are important for development of fundamental physics. This is the first of all estimation of electron anti-neutrino mass by the form of beta spectrum of tritium in the region of boundary energy. Recently here there was problem of non physical negative values. This problem can be solved by using in measurement of different in principle high-effective spectrometers, which possess improved background properties. A position-time spectrometers belongs to these apparatus, which provides the best background conditions at very large effectiveness of the measurements of tritium beta spectrum in the region of boundary energy with acceptable high resolution. An important advantage of position-time spectrometer is the possibility of

Polystyrene negative resist for high-resolution electron beam lithography

Directory of Open Access Journals (Sweden)

Ma Siqi

2011-01-01

Full Text Available Abstract We studied the exposure behavior of low molecular weight polystyrene as a negative tone electron beam lithography (EBL resist, with the goal of finding the ultimate achievable resolution. It demonstrated fairly well-defined patterning of a 20-nm period line array and a 15-nm period dot array, which are the densest patterns ever achieved using organic EBL resists. Such dense patterns can be achieved both at 20 and 5 keV beam energies using different developers. In addition to its ultra-high resolution capability, polystyrene is a simple and low-cost resist with easy process control and practically unlimited shelf life. It is also considerably more resistant to dry etching than PMMA. With a low sensitivity, it would find applications where negative resist is desired and throughput is not a major concern.

High-spatial resolution and high-spectral resolution detector for use in the measurement of solar flare hard x rays

International Nuclear Information System (INIS)

Desai, U.D.; Orwig, L.E.

1988-01-01

In the areas of high spatial resolution, the evaluation of a hard X-ray detector with 65 micron spatial resolution for operation in the energy range from 30 to 400 keV is proposed. The basic detector is a thick large-area scintillator faceplate, composed of a matrix of high-density scintillating glass fibers, attached to a proximity type image intensifier tube with a resistive-anode digital readout system. Such a detector, combined with a coded-aperture mask, would be ideal for use as a modest-sized hard X-ray imaging instrument up to X-ray energies as high as several hundred keV. As an integral part of this study it was also proposed that several techniques be critically evaluated for X-ray image coding which could be used with this detector. In the area of high spectral resolution, it is proposed to evaluate two different types of detectors for use as X-ray spectrometers for solar flares: planar silicon detectors and high-purity germanium detectors (HPGe). Instruments utilizing these high-spatial-resolution detectors for hard X-ray imaging measurements from 30 to 400 keV and high-spectral-resolution detectors for measurements over a similar energy range would be ideally suited for making crucial solar flare observations during the upcoming maximum in the solar cycle

Exploring semiconductor quantum dots and wires by high resolution electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Molina, S I [Departamento de Ciencia de los Materiales e Ing Metalurgica y Q. Inorganica, F. de Ciencias, Universidad de Cadiz, Campus Rio San Pedro. 11510 Puerto Real (Cadiz) (Spain); Galindo, P L [Departamento de Lenguajes y Sistemas Informaticos, CASEM, Universidad de Cadiz, Campus Rio San Pedro. 11510 Puerto Real (Cadiz) (Spain); Gonzalez, L; Ripalda, J M [Instituto de Microelectronica de Madrid (CNM, CSIC), Isaac Newton 8, 28760 Tres Cantos, Madrid (Spain); Varela, M; Pennycook, S J, E-mail: sergio.molina@uca.e [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge TN 37831 (United States)

2010-02-01

We review in this communication our contribution to the structural characterisation of semiconductor quantum dots and wires by high resolution electron microscopy, both in phase-contrast and Z-contrast modes. We show how these techniques contribute to predict the preferential sites of nucleation of these nanostructures, and also determine the compositional distribution in 1D and 0D nanostructures. The results presented here were produced in the framework of the European Network of Excellence entitled {sup S}elf-Assembled semiconductor Nanostructures for new Devices in photonics and Electronics (SANDiE){sup .}

High-resolution imaging in the scanning transmission electron microscope

International Nuclear Information System (INIS)

Pennycook, S.J.; Jesson, D.E.

1992-03-01

The high-resolution imaging of crystalline materials in the scanning transmission electron microscopy (STEM) is reviewed with particular emphasis on the conditions under which an incoherent image can be obtained. It is shown that a high-angle annular detector can be used to break the coherence of the imaging process, in the transverse plane through the geometry of the detector, or in three dimensions if multiphonon diffuse scattering is detected. In the latter case, each atom can be treated as a highly independent source of high-angle scattering. The most effective fast electron states are therefore tightly bound s-type Bloch states. Furthermore, they add constructively for each incident angle in the coherent STEM probe, so that s states are responsible for practically the entire image contrast. Dynamical effects are largely removed, and almost perfect incoherent imaging is achieved. s states are relatively insensitive to neighboring strings, so that incoherent imaging is maintained for superlattice and interfaces, and supercell calculations are unnecessary. With an optimum probe profile, the incoherent image represents a direct image of the crystal projection, with compositional sensitivity built in through the strong dependence of the scattering cross sections on atomic number Z

Effects of display resolution and size on primary diagnosis of chest images using a high-resolution electronic work station

International Nuclear Information System (INIS)

Fuhrman, C.R.; Cooperstein, L.A.; Herron, J.; Good, W.F.; Good, B.; Gur, D.; Maitz, G.; Tabor, E.; Hoy, R.J.

1987-01-01

To evaluate the acceptability of electronically displayed planar images, the authors have a high-resolution work station. This system utilizes a high-resolution film digitizer (100-micro resolution) interfaced to a mainframe computer and two high-resolution (2,048 X 2,048) display devices (Azuray). In a clinically simulated multiobserver blind study (19 cases and five observers) a prodetermined series of reading sessions is stored on magnetic disk and is transferred to the displays while the preceding set of images is being reviewed. Images can be linearly processed on the fly into 2,000 X 2,000 full resolution, 1,000 X 1,000 minified display, or 1,000 X 1,000 interpolated for full-size display. Results of the study indicate that radiologists accept but do not like significant minification (more than X2), and they rate 2,000 X 2,000 images as having better diagnostic quality than 1,000 X 1,000 images

Environmental high resolution electron microscopy and applications to chemical science

OpenAIRE

Boyes, Edward; Gai, Pratibha

2017-01-01

An environmental cell high resolution electron microscope (EHREM) has been developed for in situ studies of dynamic chemical reactions on the atomic scale. It allows access to metastable intermediate phases of catalysts and to sequences of reversible microstructural and chemical development associated with the activation, deactivation and poisoning of a catalyst. Materials transported through air can be restored or recreated and samples damaged, e.g. by dehydration, by the usual vacuum enviro...

High resolution, high speed ultrahigh vacuum microscopy

International Nuclear Information System (INIS)

Poppa, Helmut

2004-01-01

The history and future of transmission electron microscopy (TEM) is discussed as it refers to the eventual development of instruments and techniques applicable to the real time in situ investigation of surface processes with high resolution. To reach this objective, it was necessary to transform conventional high resolution instruments so that an ultrahigh vacuum (UHV) environment at the sample site was created, that access to the sample by various in situ sample modification procedures was provided, and that in situ sample exchanges with other integrated surface analytical systems became possible. Furthermore, high resolution image acquisition systems had to be developed to take advantage of the high speed imaging capabilities of projection imaging microscopes. These changes to conventional electron microscopy and its uses were slowly realized in a few international laboratories over a period of almost 40 years by a relatively small number of researchers crucially interested in advancing the state of the art of electron microscopy and its applications to diverse areas of interest; often concentrating on the nucleation, growth, and properties of thin films on well defined material surfaces. A part of this review is dedicated to the recognition of the major contributions to surface and thin film science by these pioneers. Finally, some of the important current developments in aberration corrected electron optics and eventual adaptations to in situ UHV microscopy are discussed. As a result of all the path breaking developments that have led to today's highly sophisticated UHV-TEM systems, integrated fundamental studies are now possible that combine many traditional surface science approaches. Combined investigations to date have involved in situ and ex situ surface microscopies such as scanning tunneling microscopy/atomic force microscopy, scanning Auger microscopy, and photoemission electron microscopy, and area-integrating techniques such as x-ray photoelectron

Carbon K-shell excitation in small molecules by high-resolution electron impact

International Nuclear Information System (INIS)

Tronc, M.; King, G.C.; Read, F.H.

1979-01-01

The excitation of 1s carbon electrons has been observed in C0, CH 4 , CF4, C0 2 , COS, C 2 H 2 and C 2 H 4 by means of the electron energy-loss technique with high resolution (70 meV in the 300 eV excitation energy range) and at an incident electron energy of 1.5 keV. The energies, widths and vibrational structures of excited states corresponding to the promotion of 1s carbon electrons to unoccupied valence and Rydberg orbitals have been obtained. The validity of the equivalent-core model, and the role of resonances caused by potential barriers, are discussed. (author)

High-resolution electron-beam patternable nanocomposite containing metal nanoparticles for plasmonics

International Nuclear Information System (INIS)

Abargues, R; Marques-Hueso, J; Canet-Ferrer, J; Pedrueza, E; Valdes, J L; Jimenez, E; MartInez-Pastor, J P

2008-01-01

Polymer nanocomposites containing noble metal nanoparticles are promising materials for plasmonic applications. In this paper, we report on a high-resolution negative-tone nanocomposite resist based on poly(vinyl alcohol) where silver nanoparticles and nanopatterns are simultaneously generated by electron-beam lithography. Our results indicate nanostructures with a relatively high concentration of nanoparticles and, consequently, an electromagnetic coupling among the nanoparticles. Therefore, the patternable nanocomposite described in this work may be a suitable material for future plasmonic circuitry

Atomic resolution three-dimensional electron diffraction microscopy

International Nuclear Information System (INIS)

Miao Jianwei; Ohsuna, Tetsu; Terasaki, Osamu; Hodgson, Keith O.; O'Keefe, Michael A.

2002-01-01

We report the development of a novel form of diffraction-based 3D microscopy to overcome resolution barriers inherent in high-resolution electron microscopy and tomography. By combining coherent electron diffraction with the oversampling phasing method, we show that the 3D structure of a nanocrystal can be determined ab initio at a resolution of 1 Angstrom from 29 simulated noisy diffraction patterns. This new form of microscopy can be used to image the 3D structures of nanocrystals and noncrystalline samples, with resolution limited only by the quality of sample diffraction

High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100-300 Å spectral banda)

Science.gov (United States)

Widmann, K.; Beiersdorfer, P.; Magee, E. W.; Boyle, D. P.; Kaita, R.; Majeski, R.

2014-11-01

We have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li+ or Li2 +, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li+ and 65 eV for the 135 Å Li2 + lines. Recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.

Improved methods for high resolution electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Taylor, J.R.

1987-04-01

Existing methods of making support films for high resolution transmission electron microscopy are investigated and novel methods are developed. Existing methods of fabricating fenestrated, metal reinforced specimen supports (microgrids) are evaluated for their potential to reduce beam induced movement of monolamellar crystals of C/sub 44/H/sub 90/ paraffin supported on thin carbon films. Improved methods of producing hydrophobic carbon films by vacuum evaporation, and improved methods of depositing well ordered monolamellar paraffin crystals on carbon films are developed. A novel technique for vacuum evaporation of metals is described which is used to reinforce microgrids. A technique is also developed to bond thin carbon films to microgrids with a polymer bonding agent. Unique biochemical methods are described to accomplish site specific covalent modification of membrane proteins. Protocols are given which covalently convert the carboxy terminus of papain cleaved bacteriorhodopsin to a free thiol. 53 refs., 19 figs., 1 tab.

Phonon spectrum of single-crystalline FeSe probed by high-resolution electron energy-loss spectroscopy

Science.gov (United States)

Zakeri, Khalil; Engelhardt, Tobias; Le Tacon, Matthieu; Wolf, Thomas

2018-06-01

Utilizing high-resolution electron energy-loss spectroscopy (HREELS) we measure the phonon frequencies of β-FeSe(001), cleaved under ultra-high vacuum conditions. At the zone center (Γ bar-point) three prominent loss features are observed at loss energies of about ≃ 20.5 and 25.6 and 40 meV. Based on the scattering selection rules we assign the observed loss features to the A1g, B1g, and A2u phonon modes of β-FeSe(001). The experimentally measured phonon frequencies do not agree with the results of density functional based calculations in which a nonmagnetic, a checkerboard or a strip antiferromagnetic order is assumed for β-FeSe(001). Our measurements suggest that, similar to the other Fe-based materials, magnetism has a profound impact on the lattice dynamics of β-FeSe(001).

Quantitative measurement of mean inner potential and specimen thickness from high-resolution off-axis electron holograms of ultra-thin layered WSe2.

Science.gov (United States)

Winkler, Florian; Tavabi, Amir H; Barthel, Juri; Duchamp, Martial; Yucelen, Emrah; Borghardt, Sven; Kardynal, Beata E; Dunin-Borkowski, Rafal E

2017-07-01

The phase and amplitude of the electron wavefunction that has passed through ultra-thin flakes of WSe 2 is measured from high-resolution off-axis electron holograms. Both the experimental measurements and corresponding computer simulations are used to show that, as a result of dynamical diffraction, the spatially averaged phase does not increase linearly with specimen thickness close to an [001] zone axis orientation even when the specimen has a thickness of only a few layers. It is then not possible to infer the local specimen thickness of the WSe 2 from either the phase or the amplitude alone. Instead, we show that the combined analysis of phase and amplitude from experimental measurements and simulations allows an accurate determination of the local specimen thickness. The relationship between phase and projected potential is shown to be approximately linear for extremely thin specimens that are tilted by several degrees in certain directions from the [001] zone axis. A knowledge of the specimen thickness then allows the electrostatic potential to be determined from the measured phase. By using this combined approach, we determine a value for the mean inner potential of WSe 2 of 18.9±0.8V, which is 12% lower than the value calculated from neutral atom scattering factors. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

High-resolution measurements of x rays from ion-atom collisions

International Nuclear Information System (INIS)

Knudson, A.R.

1974-01-01

High resolution measurements of K x-ray spectra produced by ion-atom collisions at MeV energies are presented. These measurements indicate that a distribution of L-shell vacancies accompanies K-shell excitation. The variation of these spectra as a function of incident ion energy and atomic number is discussed. Difficulties in the analysis of these spectra due to rearrangement of vacancies between the time of the collision and the time of x-ray emission are considered. The use of high resolution x-ray measurements to obtain information on projectile ion vacancy configurations is demonstrated by data for Ar ions in KCl. X-ray spectra from Al projectiles in a variety of targets were measured and the effect of target composition on these spectra is discussed

High-resolution energetic particle measurements at 6.6 R/sub E/ 1. Electron micropulsations

International Nuclear Information System (INIS)

Higbie, P.R.; Belian, R.D.; Baker, D.N.

1978-01-01

The three papers dealing with data from satellites 1976--059A which we present in this issue represent the first publication of data from the new series of charged particle analyzer (CPA) instruments designed to measure energetic particle fluxes at geosynchronous altitudes. This first report presents new results on electron micropulsation phenomena and includes a concise description of the instrument. We often observe highly periodic modulations which persist for times as long as 2 hours in the spin-averaged counting rate data. These flux oscillations occur most frequently in the 30- to 300-keV electron data but are occasionally seen in higher-energy electron or low-energy proton data. The pitch angle distributions of the observed modulated fluxes may be either 'cigar-shaped' or 'pancake-shaped.' Oscillations at different energies are in phase, although the gross counting rate may be changing in an energy-time dispersive manner. The occurrence distribution of these modulations in local time suggests that they are related to Pc 5 geomagnetic micropulsations observed at ground stations

Measuring large-scale social networks with high resolution.

Directory of Open Access Journals (Sweden)

Arkadiusz Stopczynski

Full Text Available This paper describes the deployment of a large-scale study designed to measure human interactions across a variety of communication channels, with high temporal resolution and spanning multiple years-the Copenhagen Networks Study. Specifically, we collect data on face-to-face interactions, telecommunication, social networks, location, and background information (personality, demographics, health, politics for a densely connected population of 1000 individuals, using state-of-the-art smartphones as social sensors. Here we provide an overview of the related work and describe the motivation and research agenda driving the study. Additionally, the paper details the data-types measured, and the technical infrastructure in terms of both backend and phone software, as well as an outline of the deployment procedures. We document the participant privacy procedures and their underlying principles. The paper is concluded with early results from data analysis, illustrating the importance of multi-channel high-resolution approach to data collection.

High Resolution Temperature Measurement of Liquid Stainless Steel Using Hyperspectral Imaging

Directory of Open Access Journals (Sweden)

Wim Devesse

2017-01-01

Full Text Available A contactless temperature measurement system is presented based on a hyperspectral line camera that captures the spectra in the visible and near infrared (VNIR region of a large set of closely spaced points. The measured spectra are used in a nonlinear least squares optimization routine to calculate a one-dimensional temperature profile with high spatial resolution. Measurements of a liquid melt pool of AISI 316L stainless steel show that the system is able to determine the absolute temperatures with an accuracy of 10%. The measurements are made with a spatial resolution of 12 µm/pixel, justifying its use in applications where high temperature measurements with high spatial detail are desired, such as in the laser material processing and additive manufacturing fields.

Chloride ingress profiles measured by electron probe micro analysis

DEFF Research Database (Denmark)

Jensen, Ole mejlhede; Coats, Alison M.; Glasser, Fred P.

1996-01-01

Traditional techniques for measuring chloride ingress profiles do not apply well to high performance cement paste systems; the geometric resolution of the traditional measuring techniques is too low. In this paper measurements by Electron Probe Micro Analysis (EPMA) are presented. EPMA is demonst......Traditional techniques for measuring chloride ingress profiles do not apply well to high performance cement paste systems; the geometric resolution of the traditional measuring techniques is too low. In this paper measurements by Electron Probe Micro Analysis (EPMA) are presented. EPMA...... is demonstated to determine chloride ingress in cement paste on a micrometer scale. Potential chloride ingress routes such as cracks or the paste-aggregate interface may also be characterized by EPMA. Copyright (C) 1996 Elsevier Science Ltd...

A high resolution large dynamic range TDC circuit implementation

International Nuclear Information System (INIS)

Lei Wuhu; Liu Songqiu; Ye Weiguo; Han Hui; Li Pengyu

2003-01-01

Time measurement technology is usually used in nuclear experimentation. There are many methods of time measurement. The implementation method of Time to Digital Conversion (TDC) by means of electronic is a classical technology. The range and resolution of TDC is different according with different usage. A wide range and high resolution TDC circuit, including its theory and implementation way, is introduced in this paper. The test result is also given. (authors)

A high resolution large dynamic range TDC circuit implementation

International Nuclear Information System (INIS)

Lei Wuhu; Liu Songqiu; Li Pengyu; Han Hui; Ye Yanlin

2005-01-01

Time measurement technology is usually used in nuclear experimentation. There are many methods of time measurement. The implementation method of Time to Digital Conversion (TDC) by means of electronics is a classical technology. The range and resolution of TDC is different according with different usage. A wide range and high resolution TDC circuit, including its theory and implementation way, is introduced in this paper. The test result is also given. (authors)

NaI(Tl) electron energy resolution

CERN Document Server

Mengesha, W

2002-01-01

NaI(Tl) electron energy resolution eta sub e was measured using the Modified Compton Coincidence Technique (MCCT). The MCCT allowed detection of nearly monoenergetic internal electrons resulting from the scattering of incident 662 keV gamma rays within a primary NaI(Tl) detector. Scattered gamma rays were detected using a secondary HPGe detector in a coincidence mode. Measurements were carried out for electron energies ranging from 16 to 438 keV, by varying the scattering angle. Measured HPGe coincidence spectra were deconvolved to determine the scattered energy spectra from the NaI(Tl) detector. Subsequently, the NaI(Tl) electron energy spectra were determined by subtracting the energy of scattered spectra from the incident source energy (662 keV). Using chi-squared minimization, iterative deconvolution of the internal electron energy spectra from the measured NaI(Tl) spectra was then used to determine eta sub e at the electron energy of interest. eta sub e values determined using this technique represent va...

High-resolution grazing-incidence grating spectrometer for temperature measurements of low-Z ions emitting in the 100–300 Å spectral band

Energy Technology Data Exchange (ETDEWEB)

Widmann, K., E-mail: widmann1@llnl.gov; Beiersdorfer, P.; Magee, E. W. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Boyle, D. P.; Kaita, R.; Majeski, R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2014-11-15

We have constructed a high-resolution grazing-incidence spectrometer designed for measuring the ion temperature of low-Z elements, such as Li{sup +} or Li{sup 2+}, which radiate near 199 Å and 135 Å, respectively. Based on measurements at the Livermore Electron Beam Ion Trap we have shown that the instrumental resolution is better than 48 mÅ at the 200 Å setting and better than 40 mÅ for the 135-Å range. Such a high spectral resolution corresponds to an instrumental limit for line-width based temperature measurements of about 45 eV for the 199 Å Li{sup +} and 65 eV for the 135 Å Li{sup 2+} lines. Recently obtained survey spectra from the Lithium Tokamak Experiment at the Princeton Plasma Physics Laboratory show the presence of these lithium emission lines and the expected core ion temperature of approximately 70 eV is sufficiently high to demonstrate the feasibility of utilizing our high-resolution spectrometer as an ion-temperature diagnostic.

High resolution electron energy loss spectroscopy of clean and hydrogen covered Si(001) surfaces: first principles calculations.

Science.gov (United States)

Patterson, C H

2012-09-07

Surface phonons, conductivities, and loss functions are calculated for reconstructed (2×1), p(2×2) and c(4×2) clean Si(001) surfaces, and (2×1) H and D covered Si(001) surfaces. Surface conductivities perpendicular to the surface are significantly smaller than conductivities parallel to the surface. The surface loss function is compared to high resolution electron energy loss measurements. There is good agreement between calculated loss functions and experiment for H and D covered surfaces. However, agreement between experimental data from different groups and between theory and experiment is poor for clean Si(001) surfaces. Formalisms for calculating electron energy loss spectra are reviewed and the mechanism of electron energy losses to surface vibrations is discussed.

High-resolution neutron-diffraction measurements to 8 kbar

Science.gov (United States)

Bull, C. L.; Fortes, A. D.; Ridley, C. J.; Wood, I. G.; Dobson, D. P.; Funnell, N. P.; Gibbs, A. S.; Goodway, C. M.; Sadykov, R.; Knight, K. S.

2017-10-01

We describe the capability to measure high-resolution neutron powder diffraction data to a pressure of at least 8 kbar. We have used the HRPD instrument at the ISIS neutron source and a piston-cylinder design of pressure cell machined from a null-scattering titanium zirconium alloy. Data were collected under hydrostatic conditions from an elpasolite perovskite La?NiMnO?; by virtue of a thinner cell wall on the incident-beam side of the cell, it was possible to obtain data in the instrument's highest resolution back-scattering detector banks up to a maximum pressure of 8.5 kbar.

Marvel Analysis of the Measured High-resolution Rovibronic Spectra of TiO

Science.gov (United States)

McKemmish, Laura K.; Masseron, Thomas; Sheppard, Samuel; Sandeman, Elizabeth; Schofield, Zak; Furtenbacher, Tibor; Császár, Attila G.; Tennyson, Jonathan; Sousa-Silva, Clara

2017-02-01

Accurate, experimental rovibronic energy levels, with associated labels and uncertainties, are reported for 11 low-lying electronic states of the diatomic {}48{{Ti}}16{{O}} molecule, determined using the Marvel (Measured Active Rotational-Vibrational Energy Levels) algorithm. All levels are based on lines corresponding to critically reviewed and validated high-resolution experimental spectra taken from 24 literature sources. The transition data are in the 2-22,160 cm-1 region. Out of the 49,679 measured transitions, 43,885 are triplet-triplet, 5710 are singlet-singlet, and 84 are triplet-singlet transitions. A careful analysis of the resulting experimental spectroscopic network (SN) allows 48,590 transitions to be validated. The transitions determine 93 vibrational band origins of {}48{{Ti}}16{{O}}, including 71 triplet and 22 singlet ones. There are 276 (73) triplet-triplet (singlet-singlet) band-heads derived from Marvel experimental energies, 123(38) of which have never been assigned in low- or high-resolution experiments. The highest J value, where J stands for the total angular momentum, for which an energy level is validated is 163. The number of experimentally derived triplet and singlet {}48{{Ti}}16{{O}} rovibrational energy levels is 8682 and 1882, respectively. The lists of validated lines and levels for {}48{{Ti}}16{{O}} are deposited in the supporting information to this paper.

High-resolution patterning of graphene by screen printing with a silicon stencil for highly flexible printed electronics.

Science.gov (United States)

Hyun, Woo Jin; Secor, Ethan B; Hersam, Mark C; Frisbie, C Daniel; Francis, Lorraine F

2015-01-07

High-resolution screen printing of pristine graphene is introduced for the rapid fabrication of conductive lines on flexible substrates. Well-defined silicon stencils and viscosity-controlled inks facilitate the preparation of high-quality graphene patterns as narrow as 40 μm. This strategy provides an efficient method to produce highly flexible graphene electrodes for printed electronics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas-phase synthesis of magnesium nanoparticles : A high-resolution transmission electron microscopy study

NARCIS (Netherlands)

Kooi, B.J.; Palasantzas, G.; de Hosson, J.T.M.

2006-01-01

Magnesium nanoparticles with size above 10 nm, prepared by gas-phase syntheses, were investigated by high-resolution transmission electron microscopy. The dominant particle shape is a hexagonal prism terminated by Mg(0002) and Mg{1010} facets. Oxidation of Mg yields a MgO shell (similar to 3 nm

Development of an Apparatus for High-Resolution Auger Photoelectron Coincidence Spectroscopy (APECS) and Electron Ion Coincidence (EICO) Spectroscopy

Science.gov (United States)

Kakiuchi, Takuhiro; Hashimoto, Shogo; Fujita, Narihiko; Mase, Kazuhiko; Tanaka, Masatoshi; Okusawa, Makoto

We have developed an electron electron ion coincidence (EEICO) apparatus for high-resolution Auger photoelectron coincidence spectroscopy (APECS) and electron ion coincidence (EICO) spectroscopy. It consists of a coaxially symmetric mirror electron energy analyzer (ASMA), a miniature double-pass cylindrical mirror electron energy analyzer (DP-CMA), a miniature time-of-flight ion mass spectrometer (TOF-MS), a magnetic shield, an xyz stage, a tilt-adjustment mechanism, and a conflat flange with an outer diameter of 203 mm. A sample surface was irradiated by synchrotron radiation, and emitted electrons were energy-analyzed and detected by the ASMA and the DP-CMA, while desorbed ions were mass-analyzed and detected by the TOF-MS. The performance of the new EEICO analyzer was evaluated by measuring Si 2p photoelectron spectra of clean Si(001)-2×1 and Si(111)-7×7, and by measuring Si-L23VV-Si-2p Auger photoelectron coincidence spectra (Si-L23VV-Si-2p APECS) of clean Si(001)-2×1.

High-resolution transmission electron microscopy and energetics of flattened carbon nonoshells

International Nuclear Information System (INIS)

Bourgeois, L.N.; Bursill, L.A.

1998-01-01

When examined under a high-resolution transmission electron microscope, carbon soot produced alongside buckytubes in an arc-discharge is found to contain a small percentage of flattened carbon shells. These objects are shown to be small graphite flakes which eliminated their dangling bonds by terminating their edges with highly curved junctions. Ideal models for these structures are presented, and their energy estimated. The calculations show that the establishment of highly curved junctions is energetically favourable for a graphite flake in an inert atmosphere. Flattened shells also appear more stable than their 'inflated' counterparts (fullerene 'onions' and buckytubes) when the shell dimensions obey specific criteria.(authors)

Electron Temperatures in W51 Complex from High Resolution, Low ...

Indian Academy of Sciences (India)

2001-03-09

Mar 9, 2001 ... kinematics and local thermodynamic equilibrium (LTE) electron temperature (Te) of this region. H109α RRL observations by Wilsonet al.(1970) with a resolution of 4 and by Pankonin et al. (1979) with a resolution of 2.6 show that Te ∼ 6000 K in G49.5-0.4. Lower frequency observations for H137β and ...

DEVELOPMENT OF A HIGH RATE HIGH RESOLUTION DETECTOR FOR EXAFS EXPERIMENTS.

Energy Technology Data Exchange (ETDEWEB)

DE GERONIMO,G.; O CONNOR,P.; BEUTTENMULLER,R.H.; LI,Z.; KUCZEWSKI,A.J.; SIDDONS,D.P.

2002-11-10

A new detector for EXAFS experiments is being developed. It is based on a multi-element Si sensor and dedicated readout ASICs. The sensor is composed of 384 pixels, each having 1 mm{sup 2} area, arranged in four quadrants of 12 x 8 elements, and wire-bonded to 32-channel front-end ASICs. Each channel implements low noise preamplification with self-adaptive continuous reset, high order shaper, band-gap referenced baseline stabilizer, one threshold comparator and two DAC adjustable window comparators, each followed by a 24-bit counter. Fabricated in 0.35{micro}m CMOS dissipates about 8mW per channel. First measurements show at room temperature a resolution of 14 rms electrons without the detector and of 40 rms electrons (340eV) with the detector connected and biased. Cooling at -35C a FWHM of 205eV (167eV from electronics) was measured at the Mn-K{alpha} line. A resolution of about 300eV was measured for rates approaching 100kcps/cm{sup 2} per channel, corresponding to an overall rate in excess of 10MHz/cm{sup 2}. A channel-to-channel threshold dispersion after DACs adjustment of 2.5 rms electrons was also measured.

An ASIC implementation of digital front-end electronics for a high resolution PET scanner

International Nuclear Information System (INIS)

Newport, D.F.; Young, J.W.

1993-01-01

AN Application Specific Integrated Circuit (ASIC) has been designed and fabricated which implements many of the current functions found in the digital front-end electronics for a high resolution Positron Emission Tomography (PET) scanner. The ASIC performs crystal selection, energy qualification, time correction, and event counting functions for block technology high resolution PET scanners. Digitized x and y position, event energy, and time information are used by the ASIC to determine block crystal number, qualify the event based on energy, and correct the event time. In addition, event counting and block dead time calculations are performed for system dead time corrections. A loadable sequencer for controlling the analog front-end electronics is also implemented. The ASIC is implemented in a 37,000 gate, 1.0 micron CMOS gate-array and is capable of handling 4 million events/second while reducing parts count, cost, and power consumption over current board-level designs

High-Resolution Electron-Impact Study of the Far-Ultraviolet Emission Spectrum of Molecular Hydrogen

Science.gov (United States)

Liu, Xian-Ming; Ahmed, Syed M.; Multari, Rosalie A.; James, Geoffrey K.; Ajello, Joseph M.

1995-01-01

The emission spectrum of molecular hydrogen produced by electron-impact excitation at 100 eV has been measured in the wavelength range 1140-1690 A. High-resolution, optically thin spectra (delta(lambda) = 0.136 A) of the far-ultraviolet (FUV) Lyman and Werner band systems have been obtained with a newly constructed 3 m spectrometer. Synthetic spectral intensities based on the transition probabilities calculated by Abgrall et al. are in very good agreement with experimentally observed intensities. Previous modeling that utilized Allison & Daigarno band transition probabilities with Hoenl-London factors breaks down when the transition moment has significant J dependence or when ro-vibrational coupling is significant. Ro-vibrational perturbation between upsilon = 14 of the B(sup 1)Sigma(sup +, sub u) state and upsilon = 3 of the C(sup 1)Pi(sub u) state and the rotational dependence of the transition moment in the bands of the Lyman system are examined. Complete high-resolution experimental reference FUV spectra, together with the model synthetic spectra based on the Abgrall transition probabilities, are presented. An improved calibration standard is obtained, and an accurate calibration of the 3 m spectrometer has been achieved.

High resolution electron microscopy and electron diffraction of YBa/sub 2/Cu/sub 3/O/sub 7-x/

International Nuclear Information System (INIS)

Krakow, W.; Shaw, T.M.

1988-01-01

Experimental high resolution electron micrographs and computer simulation experiments have been used to evaluate the visibility of the atomic constituents of YBa/sub 2/Cu/sub 3/O/sub 7-x/. In practice, the detection of oxygen has not been possible in contradiction to that predicted by modelling of perfect crystalline material. Preliminary computer experiments of the electron diffraction patterns when oxygen vacancies are introduced on the Cu-O sheets separating Ba layers show the diffuse streaks characteristic of short range ordering

Quantitative analysis of localized stresses in irradiated stainless steels using high resolution electron backscatter diffraction and molecular dynamics modeling

International Nuclear Information System (INIS)

Johnson, D.C.; Kuhr, B.; Farkas, D.; Was, G.S.

2016-01-01

Quantitative measurements of stress near dislocation channel–grain boundary (DC–GB) interaction sites were made using high resolution electron backscatter diffraction (HREBSD) and have been compared with molecular dynamics (MD) simulations. Tensile stress normal to the grain boundary was significantly elevated at discontinuous DC–GB intersections with peak magnitudes roughly an order of magnitude greater than at sites where slip transfer occurred. These results constitute the first measurement of stress amplification at DC–GB intersections and provide support to the theory that high normal stress at the grain boundary may be a key driver for the initiation of irradiation assisted stress corrosion cracks.

ELECTRON BUNCH CHARACTERIZATION WITH SUBPICOSECOND RESOLUTION USING ELECTRO-OPTIC TECHNIQUE

International Nuclear Information System (INIS)

SEMERTZIDIS, Y.K.; CASTILLO, V.; LARSEN, R.; LAZARUS, D.M.; NIKAS, D.; OZBEN, C.; SRINIVASAN-RAO, T.; STILLMAN, A.; TSANG, T.; KOWALSKI, L.

2001-01-01

In the past decade, the bunch lengths of electrons in accelerators have decreased dramatically and are in the range off a few millimeters. Measurement of the length as well as the longitudinal profile of these short bunches have been a topic of research in a number of institutions. One of the techniques uses the electric field induced by the passage of electrons in the vicinity of a birefringent crystal to change its optical characteristics. Well-established electro-optic techniques can then be used to measure the temporal characteristics of the electron bunch. The inherent fast response of the crystal facilitates the measurement to femtosecond time resolution. However, the resolution in experiments so far has been limited to 70 ps, by the bandwidth of the detection equipment. Use of a streak camera can improve this resolution to a few picoseconds. In this paper we present a novel, non-invasive, single-shot approach to improve the resolution to tens of femtoseconds so that sub mm bunch length can be measured

Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images

International Nuclear Information System (INIS)

Lee, Z.; Rose, H.; Lehtinen, O.; Biskupek, J.; Kaiser, U.

2014-01-01

In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions. - Highlights: • The definition of dose-dependent atom contrast is introduced. • The dependence of the signal-to-noise ratio, atom contrast and specimen resolution on electron dose and sampling is explored. • The optimum sampling can be determined according to different dose conditions

Single-shot 35 fs temporal resolution electron shadowgraphy

Energy Technology Data Exchange (ETDEWEB)

Scoby, C. M.; Li, R. K.; Threlkeld, E.; To, H.; Musumeci, P. [Department of Physics and Astronomy, UCLA, Los Angeles, California 90095 (United States)

2013-01-14

We obtain single-shot time-resolved shadowgraph images of the electromagnetic fields resulting from the interaction of a high intensity ultrashort laser pulse with a metal surface. Using a high brightness relativistic electron beam and a high streaking speed radiofrequency deflector, we report <35 fs temporal resolution enabling a direct visualization of the retarded-time dominated field evolution which follows the laser-induced charge emission. A model including the finite signal propagation speed well reproduces the data and yields measurements of fundamental parameters in short pulse laser-matter interaction such as the amount of emitted charge and the emission time scale.

Single-shot 35 fs temporal resolution electron shadowgraphy

International Nuclear Information System (INIS)

Scoby, C. M.; Li, R. K.; Threlkeld, E.; To, H.; Musumeci, P.

2013-01-01

We obtain single-shot time-resolved shadowgraph images of the electromagnetic fields resulting from the interaction of a high intensity ultrashort laser pulse with a metal surface. Using a high brightness relativistic electron beam and a high streaking speed radiofrequency deflector, we report <35 fs temporal resolution enabling a direct visualization of the retarded-time dominated field evolution which follows the laser-induced charge emission. A model including the finite signal propagation speed well reproduces the data and yields measurements of fundamental parameters in short pulse laser-matter interaction such as the amount of emitted charge and the emission time scale.

Minimal exposure technique in the Cambridge University 600kV high resolution electron microscope

International Nuclear Information System (INIS)

Fryer, J.R.; Cleaver, J.R.A.; Smith, D.J.

1980-01-01

Radiation damage due to the incident electron beam imposes a fundamental limitation on the information obtainable by electron microscopy about organic materials; it is desirable therefore that exposure of the specimen to the electron beam should be restricted to the actual period during which the image is being recorded. A description is given of methods employed in the observation of the organic aromatic hydrocarbons quaterrylene, ovalene and coronene with the Cambridge University 600kV high resolution electron microscope (HREM). In particular, the condenser-objective mode of operation of this microscope lends itself to the use of an area-defining aperture below the second condenser lens conjugate with the specimen. Furthermore, operation at the higher accelerating voltage of this instrument could be anticipated to reduce the rate of damage, depending on the dominant beam-specimen interaction, whilst the increased width of the first broad band of the contrast transfer function of this microscope at the optimum defocus may overcome the reported resolution limitation of current 100kV microscopes for the observation of related materials. (author)

Magnetic lens apparatus for a low-voltage high-resolution electron microscope

Science.gov (United States)

Crewe, Albert V.

1996-01-01

A lens apparatus in which a beam of charged particles of low accelerating voltage is brought to a focus by a magnetic field, the lens being situated behind the target position. The lens comprises an electrically-conducting coil arranged around the axis of the beam and a magnetic pole piece extending along the axis of the beam at least within the space surrounded by the coil. The lens apparatus comprises the sole focusing lens for high-resolution imaging in a low-voltage scanning electron microscope.

HEPD on NEXTSat-1: A High Energy Particle Detector for Measurements of Precipitating Radiation Belt Electrons

Science.gov (United States)

Sohn, Jongdae; Lee, Jaejin; Min, Kyoungwook; Lee, Junchan; Lee, Seunguk; Lee, Daeyoung; Jo, Gyeongbok; Yi, Yu; Na, Gowoon; Kang, Kyung-In; Shin, Goo-Hwan

2018-05-01

Radiation belt particles of the inner magnetosphere precipitate into the atmosphere in the subauroral regions when they are pitch-angle scattered into the loss cone by wave-particle interactions. Such particle precipitations are known to be especially enhanced during space storms, though they can also occur during quiet times. The observed characteristics of precipitating electrons can be distinctively different, in their time series as well as in their spectra, depending on the waves involved. The present paper describes the High Energy Particle Detector (HEPD) on board the Next Generation Small Satellite-1 (NEXTSat-1), which will measure these radiation belt electrons from a low-Earth polar orbit satellite to study the mechanisms related to electron precipitation in the sub-auroral regions. The HEPD is based on silicon barrier detectors and consists of three telescopes that are mounted on the satellite to have angles of 0°. 45°, and 90°, respectively with the local geomagnetic field during observations. With a high time resolution of 32 Hz and a high spectral resolution of 11 channels over the energy range from 350 keV to 2 MeV, together with the pitch angle information provided by the three telescopes, HEPD is capable of identifying physical processes, such as microbursts and dust-side relativistic electron precipitation (DREP) events associated with electron precipitations. NextSat-1 is scheduled for launch in early 2018.

MARVEL analysis of the measured high-resolution spectra of 14NH3

International Nuclear Information System (INIS)

Al Derzi, Afaf R.; Furtenbacher, Tibor; Tennyson, Jonathan; Yurchenko, Sergei N.; Császár, Attila G.

2015-01-01

Accurate, experimental rotational–vibrational energy levels and line positions, with associated labels and uncertainties, are reported for the ground electronic state of the symmetric-top 14 NH 3 molecule. All levels and lines are based on critically reviewed and validated high-resolution experimental spectra taken from 56 literature sources. The transition data are in the 0.7–17 000 cm −1 region, with a large gap between 7000 and 15 000 cm −1 . The MARVEL (Measured Active Rotational–Vibrational Energy Levels) algorithm is used to determine the energy levels. Out of the 29 450 measured transitions 10 041 and 18 947 belong to ortho- and para- 14 NH 3 , respectively. A careful analysis of the related experimental spectroscopic network (SN) allows 28 530 of the measured transitions to be validated, 18 178 of these are unique, while 462 transitions belong to floating components. Despite the large number of spectroscopic measurements published over the last 80 years, the transitions determine only 30 vibrational band origins of 14 NH 3 , 8 for ortho- and 22 for para- 14 NH 3 . The highest J value, where J stands for the rotational quantum number, for which an energy level is validated is 31. The number of experimental-quality ortho- and para- 14 NH 3 rovibrational energy levels is 1724 and 3237, respectively. The MARVEL energy levels are checked against ones in the BYTe first-principles database, determined previously. The lists of validated lines and levels for 14 NH 3 are deposited in the Supporting Information to this paper. Combination of the MARVEL energy levels with first-principles absorption intensities yields a huge number of experimental-quality rovibrational lines, which should prove to be useful for the understanding of future complex high-resolution spectroscopy on 14 NH 3 ; these lines are also deposited in the Supporting Information to this paper

MARVEL analysis of the measured high-resolution spectra of 14NH3

Science.gov (United States)

Al Derzi, Afaf R.; Furtenbacher, Tibor; Tennyson, Jonathan; Yurchenko, Sergei N.; Császár, Attila G.

2015-08-01

Accurate, experimental rotational-vibrational energy levels and line positions, with associated labels and uncertainties, are reported for the ground electronic state of the symmetric-top 14NH3 molecule. All levels and lines are based on critically reviewed and validated high-resolution experimental spectra taken from 56 literature sources. The transition data are in the 0.7-17 000 cm-1 region, with a large gap between 7000 and 15 000 cm-1. The MARVEL (Measured Active Rotational-Vibrational Energy Levels) algorithm is used to determine the energy levels. Out of the 29 450 measured transitions 10 041 and 18 947 belong to ortho- and para-14NH3, respectively. A careful analysis of the related experimental spectroscopic network (SN) allows 28 530 of the measured transitions to be validated, 18 178 of these are unique, while 462 transitions belong to floating components. Despite the large number of spectroscopic measurements published over the last 80 years, the transitions determine only 30 vibrational band origins of 14NH3, 8 for ortho- and 22 for para-14NH3. The highest J value, where J stands for the rotational quantum number, for which an energy level is validated is 31. The number of experimental-quality ortho- and para-14NH3 rovibrational energy levels is 1724 and 3237, respectively. The MARVEL energy levels are checked against ones in the BYTe first-principles database, determined previously. The lists of validated lines and levels for 14NH3 are deposited in the Supporting Information to this paper. Combination of the MARVEL energy levels with first-principles absorption intensities yields a huge number of experimental-quality rovibrational lines, which should prove to be useful for the understanding of future complex high-resolution spectroscopy on 14NH3; these lines are also deposited in the Supporting Information to this paper.

High-resolution transmission measurements of CO2 at high temperatures for industrial applications

DEFF Research Database (Denmark)

Evseev, Vadim; Fateev, Alexander; Clausen, Sønnik

2012-01-01

. The spectra have been recorded in a high-temperature flow gas cell and using a Fourier transform infrared (FTIR) spectrometer at a nominal resolution of 0.125 cm-1. The volume fractions of CO2 in the measurements were 1,10 and 100%. The measurements have been validated by comparison with medium...

Characterisation of radiation damage in perovskite using high angular resolution electron channeling x-ray spectroscopy (HARECXS)

International Nuclear Information System (INIS)

Smith, K.L.; Zaluzec, N.J.

2002-01-01

Full text: Predicting and/or modelling the occurrence of radiation damage induced defects and their effects on physical properties (eg. amorphisation induced swelling, electrical conductivity., optical response etc.) in ceramic phases requires knowledge of the displacement energies, E d , of cations and anions in those phases. In this study, High Angular Resolution Electron Channelling X-ray Spectroscopy (HARECXS) spectra were collected from perovskite (CaTiO 3 ) samples that had been exposed to high-energy electrons or high-energy heavy ions. Calculations based on experimental data were then used to indicate the E d of the cations in perovskite. The HARECXS measurements were conducted on a Philips EM 420T AEM (LaB6 source, operated at 120 kV) fitted with an EDAX ultra thin window Si(Li) detector. The specimen was first manually oriented to an appropriate zone axis. Then control of the relative orientation of the incident probe was accomplished via direct computer control of the beam tilt coils, Typical acquisition times for a complete two-dimensional scan were 18-24 hours, while one dimensional scans ranged from 1-5 hours. Our experiments established that: a) HARECXS can detect radiation damage in perovskite caused by either high energy heavy ions or high energy electrons, b) the HARECXS signature of perovskite shows a systematic change with ion dose, c) HARECXS detects damage in perovskite that has been irradiated with 900kV electrons and does not detect damage in perovskite that has been irradiated with 620kV electrons, indicating the existance of an electron irradiation damage threshold. Calculations based on the latter results indicate that the displacement energy, E d of calcium and titanium in perovskite lie between 50 and 85eV. Copyright (2002) Australian Society for Electron Microscopy Inc

Performance of high-resolution X-band radar for rainfall measurement in The Netherlands

Directory of Open Access Journals (Sweden)

C. Z. van de Beek

2010-02-01

Full Text Available This study presents an analysis of 195 rainfall events gathered with the X-band weather radar SOLIDAR and a tipping bucket rain gauge network near Delft, The Netherlands, between May 1993 and April 1994. The aim of this paper is to present a thorough analysis of a climatological dataset using a high spatial (120 m and temporal (16 s resolution X-band radar. This makes it a study of the potential for high-resolution rainfall measurements with non-polarimetric X-band radar over flat terrain. An appropriate radar reflectivity – rain rate relation is derived from measurements of raindrop size distributions and compared with radar – rain gauge data. The radar calibration is assessed using a long-term comparison of rain gauge measurements with corresponding radar reflectivities as well as by analyzing the evolution of the stability of ground clutter areas over time. Three different methods for ground clutter correction as well as the effectiveness of forward and backward attenuation correction algorithms have been studied. Five individual rainfall events are discussed in detail to illustrate the strengths and weaknesses of high-resolution X-band radar and the effectiveness of the presented correction methods. X-band radar is found to be able to measure the space-time variation of rainfall at high resolution, far greater than what can be achieved by rain gauge networks or a typical operational C-band weather radar. On the other hand, SOLIDAR can suffer from receiver saturation, wet radome attenuation as well as signal loss along the path. During very strong convective situations the signal can even be lost completely. In combination with several rain gauges for quality control, high resolution X-band radar is considered to be suitable for rainfall monitoring over relatively small (urban catchments. These results offer great prospects for the new high resolution polarimetric doppler X-band radar IDRA.

Graphene-enabled electron microscopy and correlated super-resolution microscopy of wet cells.

Science.gov (United States)

Wojcik, Michal; Hauser, Margaret; Li, Wan; Moon, Seonah; Xu, Ke

2015-06-11

The application of electron microscopy to hydrated biological samples has been limited by high-vacuum operating conditions. Traditional methods utilize harsh and laborious sample dehydration procedures, often leading to structural artefacts and creating difficulties for correlating results with high-resolution fluorescence microscopy. Here, we utilize graphene, a single-atom-thick carbon meshwork, as the thinnest possible impermeable and conductive membrane to protect animal cells from vacuum, thus enabling high-resolution electron microscopy of wet and untreated whole cells with exceptional ease. Our approach further allows for facile correlative super-resolution and electron microscopy of wet cells directly on the culturing substrate. In particular, individual cytoskeletal actin filaments are resolved in hydrated samples through electron microscopy and well correlated with super-resolution results.

Gas-phase synthesis of magnesium nanoparticles: A high-resolution transmission electron microscopy study

International Nuclear Information System (INIS)

Kooi, B. J.; Palasantzas, G.; De Hosson, J. Th. M.

2006-01-01

Magnesium nanoparticles with size above 10 nm, prepared by gas-phase syntheses, were investigated by high-resolution transmission electron microscopy. The dominant particle shape is a hexagonal prism terminated by Mg(0002) and Mg(1010) facets. Oxidation of Mg yields a MgO shell (∼3 nm thick), which has an orientation relation with the Mg. Inhomogeneous facet oxidation influences their growth kinetics resulting in a relatively broad size and shape distribution. Faceted voids between Mg and MgO shells indicate a fast outward diffusion of Mg and vacancy rearrangement into voids. The faceting of polar (220) planes is assisted by electron irradiation

A high resolution electron microscopy investigation of curvature in multilayer graphite sheets

International Nuclear Information System (INIS)

Wang Zhenxia; Hu Jun; Wang Wenmin; Yu Guoqing

1998-01-01

Here the authors report a carbon sample generated by ultrasonic wave high oriented pyrolytic graphite (HOPG) in ethanol, water or ethanol-water mixed solution. High resolution transmission electron microscopy (HRTEM) revealed many multilayer graphite sheets with a total curved angle that is multiples of θ 0 (= 30 degree C). Close examination of the micrographs showed that the curvature is accomplished by bending the lattice planes. A possible explanation for the curvature in multilayer graphite sheets is discussed based on the conformation of graphite symmetry axes and the formation of sp 3 -like line defects in the sp 2 graphitic network

Design and implementation of an optimal laser pulse front tilting scheme for ultrafast electron diffraction in reflection geometry with high temporal resolution

Directory of Open Access Journals (Sweden)

Francesco Pennacchio

2017-07-01

Full Text Available Ultrafast electron diffraction is a powerful technique to investigate out-of-equilibrium atomic dynamics in solids with high temporal resolution. When diffraction is performed in reflection geometry, the main limitation is the mismatch in group velocity between the overlapping pump light and the electron probe pulses, which affects the overall temporal resolution of the experiment. A solution already available in the literature involved pulse front tilt of the pump beam at the sample, providing a sub-picosecond time resolution. However, in the reported optical scheme, the tilted pulse is characterized by a temporal chirp of about 1 ps at 1 mm away from the centre of the beam, which limits the investigation of surface dynamics in large crystals. In this paper, we propose an optimal tilting scheme designed for a radio-frequency-compressed ultrafast electron diffraction setup working in reflection geometry with 30 keV electron pulses containing up to 105 electrons/pulse. To characterize our scheme, we performed optical cross-correlation measurements, obtaining an average temporal width of the tilted pulse lower than 250 fs. The calibration of the electron-laser temporal overlap was obtained by monitoring the spatial profile of the electron beam when interacting with the plasma optically induced at the apex of a copper needle (plasma lensing effect. Finally, we report the first time-resolved results obtained on graphite, where the electron-phonon coupling dynamics is observed, showing an overall temporal resolution in the sub-500 fs regime. The successful implementation of this configuration opens the way to directly probe structural dynamics of low-dimensional systems in the sub-picosecond regime, with pulsed electrons.

Zeolites - a high resolution electron microscopy study

International Nuclear Information System (INIS)

Alfredsson, V.

1994-10-01

High resolution transmission electron microscopy (HRTEM) has been used to investigate a number of zeolites (EMT, FAU, LTL, MFI and MOR) and a member of the mesoporous M41S family. The electron optical artefact, manifested as a dark spot in the projected centre of the large zeolite channels, caused by insufficient transfer of certain reflections in the objective lens has been explained. The artefact severely hinders observation of materials confined in the zeolite channels and cavities. It is shown how to circumvent the artefact problem and how to image confined materials in spite of disturbance caused by the artefact. Image processing by means of a Wiener filter has been applied for removal of the artefact. The detailed surface structure of FAU has been investigated. Comparison of experimental micrographs with images simulated using different surface models indicates that the surface can be terminated in different ways depending on synthesis methods. The dealuminated form of FAU (USY) is covered by an amorphous region. Platinum incorporated in FAU has a preponderance to aggregate in the (111) twin planes, probably due to a local difference in cage structure with more spacious cages. It is shown that platinum is intra-zeolitic as opposed to being located on the external surface of the zeolite crystal. This could be deduced from tomography of ultra-thin sections among observations. HRTEM studies of the mesoporous MCM-41 show that the pores have a hexagonal shape and also supports the mechanistic model proposed which involves a cooperative formation of a mesophase including the silicate species as well as the surfactant. 66 refs, 24 figs

Electron diffraction and high-resolution transmission electron microscopy of the high temperature crystal structures of GexSb2Te3+x (x=1,2,3) phase change material

NARCIS (Netherlands)

Kooi, B.J.; de Hosson, J.T.M.

2002-01-01

The crystal structures of GeSb2Te4, Ge2Sb2Te5, and Ge3Sb2Te6 were determined using electron diffraction and high-resolution transmission electron microscopy. The structure determined for the former two crystals deviates from the ones proposed in the literature. These crystal structures were

High resolution wind turbine wake measurements with a scanning lidar

DEFF Research Database (Denmark)

Herges, T. G.; Maniaci, D. C.; Naughton, B. T.

2017-01-01

High-resolution lidar wake measurements are part of an ongoing field campaign being conducted at the Scaled Wind Farm Technology facility by Sandia National Laboratories and the National Renewable Energy Laboratory using a customized scanning lidar from the Technical University of Denmark. One...

Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy

International Nuclear Information System (INIS)

Van Aert, S.; Verbeeck, J.; Erni, R.; Bals, S.; Luysberg, M.; Dyck, D. Van; Tendeloo, G. Van

2009-01-01

A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.

High-resolution electron microscopy study of electron-irradiation-induced crystalline-to-amorphous transition in α-SiC single crystals

International Nuclear Information System (INIS)

Inui, H.; Mori, H.; Sakata, T.

1992-01-01

An electron-irradiation-induced crystalline-to-amorphous (CA) transition in α-SiC has been studied by high-resolution electron microscopy (HREM). The irradiation-produced damage structure was examined as a function of dose of electrons by taking high-resolution maps extending from the unirradiated crystalline region to the completely amorphized region. In the intermediate region between those two regions, that is in the CA transition region, the damage structure was essentially a mixture of crystalline and amorphous phases. The volume fraction of the amorphous phase was found to increase with increasing dose of electrons and no discrete crystalline-amorphous interface was observed in the CA transition region. These facts indicate the heterogeneous and gradual nature of the CA transition. In the transition region close to the unirradiated crystalline region, a sort of fragmentation of the crystal lattice was observed to occur, crystallites with slightly different orientations with respect to the parent crystal were formed owing to the strain around the dispersed local amorphous regions. In the transition region close to the amorphized region, these crystallites were reduced in size and were embedded in an amorphous matrix. This damage structure is the result of the increased volume fraction of the amorphous phase. In the completely amorphized region, no lattice fringes were recognized in the HREM images. The atomistic process of the CA transition is discussed on the basis of the present results and those from previous studies. (Author)

Performance of ultrahigh resolution electron microscope JEM-4000EX and some applications of high Tc superconductors

International Nuclear Information System (INIS)

Honda, T.; Ibe, K.; Ishida, Y.; Kersker, M.M.

1989-01-01

The high resolution electron microscope is powerful for modern materials science because of its direct observation capability for the atomic structure of materials. the JEM-4000EX, a 400 kV accelerating voltage electron microscope whose objective lens has a 1 mm spherical aberration coefficient, has a 0.168 nm theoretical resolving power. Using this microscope, atomic structure images of high Tc superconductor such as Y-Ba-Cu-O, Bi-Ca-Sr-Cu-O and Tl-Ca-Ba-Cu-O are reported

Preservation of high resolution protein structure by cryo-electron microscopy of vitreous sections

International Nuclear Information System (INIS)

Sader, Kasim; Studer, Daniel; Zuber, Benoit; Gnaegi, Helmut; Trinick, John

2009-01-01

We have quantitated the degree of structural preservation in cryo-sections of a vitrified biological specimen. Previous studies have used sections of periodic specimens to assess the resolution present, but preservation before sectioning was not assessed and so the damage due particularly to cutting was not clear. In this study large single crystals of lysozyme were vitrified and from these X-ray diffraction patterns extending to better than 2.1 A were obtained. The crystals were high pressure frozen in 30% dextran, and cryo-sectioned using a diamond knife. In the best case, preservation to a resolution of 7.9 A was shown by electron diffraction, the first observation of sub-nanometre structural preservation in a vitreous section.

Electron beam fabrication and characterization of high- resolution magnetic force microscopy tips

NARCIS (Netherlands)

Ruhrig, M.; Rührig, M.; Porthun, S.; Porthun, S.; Lodder, J.C.; Mc vitie, S.; Heyderman, L.J.; Johnston, A.B.; Chapman, J.N.

1996-01-01

The stray field, magnetic microstructure, and switching behavior of high‐resolution electron beam fabricated thin film tips for magnetic force microscopy (MFM) are investigated with different imaging modes in a transmission electron microscope (TEM). As the tiny smooth carbon needles covered with a

A graphene oxide-carbon nanotube grid for high-resolution transmission electron microscopy of nanomaterials

International Nuclear Information System (INIS)

Zhang Lina; Zhang Haoxu; Zhou Ruifeng; Chen Zhuo; Li Qunqing; Fan Shoushan; Jiang Kaili; Ge Guanglu; Liu Renxiao

2011-01-01

A novel grid for use in transmission electron microscopy is developed. The supporting film of the grid is composed of thin graphene oxide films overlying a super-aligned carbon nanotube network. The composite film combines the advantages of graphene oxide and carbon nanotube networks and has the following properties: it is ultra-thin, it has a large flat and smooth effective supporting area with a homogeneous amorphous appearance, high stability, and good conductivity. The graphene oxide-carbon nanotube grid has a distinct advantage when characterizing the fine structure of a mass of nanomaterials over conventional amorphous carbon grids. Clear high-resolution transmission electron microscopy images of various nanomaterials are obtained easily using the new grids.

Resolution and Efficiency of Monitored Drift-Tube Chambers with Final Read-out Electronics at High Background Rates

CERN Document Server

Dubbert, J; Kortner, O; Kroha, H; Manz, A; Mohrdieck-Möck, S; Rauscher, F; Richter, R; Staude, A; Stiller, W

2003-01-01

The performance of a monitored drift-tube chamber for ATLAS with the final read-out electronics was tested at the Gamma Irradiation facility at CERN under varyin photon irradiation rates of up to 990~Hz\\,cm$^{-2}$ which corresponds to 10 times the highest background rate expected in ATLAS. The signal pulse-height measurement of the final read-out electronics was used to perform time-slewing corrections. The corrections improve the average single-tube resolution from 106~$\\mu$m to 89~$\\mu$m at the nominal discriminator threshold of 44~mV without irradiation, and from 114~$\\mu$m to 89~$\\mu$m at the maximum nominal irradiation rate in ATLAS of 100~Hz\\,cm$^{-2}$. The reduction of the threshold from 44~mV to 34~mV and the time-slewing corrections lead to an average single-tube resolution of 82~$\\mu$m without photon background and of 89~$\\mu$m at 100~Hz\\,cm$^{-2}$. The measured muon detection efficiency agrees with the expectation for the final read-out electronics.

High-resolution gamma-ray measurement systems using a compact electro- mechanically cooled detector system and intelligent software

International Nuclear Information System (INIS)

Buckley, W.M.; Carlson, J.B.; Neufeld, K.W.

1995-01-01

Obtaining high-resolution gamma-ray measurements using high-purity germanium (HPGe) detectors in the field has been of limited practicality due to the need to use and maintain a supply of liquid nitrogen (LN 2 ). This same constraint limits high-resolution gamma measurements in unattended safeguards or treaty Verification applications. We are developing detectors and software to greatly extend the applicability of high-resolution germanium-based measurements for these situations

An Inexpensive High-Temporal Resolution Electronic Sun Journal for Monitoring Personal Day to Day Sun Exposure Patterns

Directory of Open Access Journals (Sweden)

Nathan J. Downs

2017-11-01

Full Text Available Exposure to natural sunlight, specifically solar ultraviolet (UV radiation contributes to lifetime risks of skin cancer, eye disease, and diseases associated with vitamin D insufficiency. Improved knowledge of personal sun exposure patterns can inform public health policy; and help target high-risk population groups. Subsequently, an extensive number of studies have been conducted to measure personal solar UV exposure in a variety of settings. Many of these studies, however, use digital or paper-based journals (self-reported volunteer recall, or employ cost prohibitive electronic UV dosimeters (that limit the size of sample populations, to estimate periods of exposure. A cost effective personal electronic sun journal (ESJ built from readily available infrared photodiodes is presented in this research. The ESJ can be used to complement traditional UV dosimeters that measure total biologically effective exposure by providing a time-stamped sun exposure record. The ESJ can be easily attached to clothing and data logged to personal devices (including fitness monitors or smartphones. The ESJ improves upon self-reported exposure recording and is a cost effective high-temporal resolution option for monitoring personal sun exposure behavior in large population studies.

Electron bunch length measurement with a wakefield radiation decelerator

Directory of Open Access Journals (Sweden)

Weiwei Li

2014-03-01

Full Text Available In this paper, we propose a novel method to measure the electron bunch length with a dielectric wakefield radiation (DWR decelerator which is composed of two dielectric-lined waveguides (DLWs and an electron spectrometer. When an electron beam passes through a DLW, the DWR is excited which leads to an energy loss of the electron beam. The energy loss is found to be largely dependent on the electron bunch length and can be easily measured by an electron spectrometer which is essential for a normal accelerator facility. Our study shows that this method has a high resolution and a great simplicity.

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue.

Science.gov (United States)

Sakadzić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A; Mandeville, Emiri T; Srinivasan, Vivek J; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H; Vinogradov, Sergei A; Boas, David A

2010-09-01

Measurements of oxygen partial pressure (pO(2)) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO(2) measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here we report to our knowledge the first practical in vivo two-photon high-resolution pO(2) measurements in small rodents' cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 microm, sub-second temporal resolution and requires low probe concentration. The properties of the probe allowed for direct high-resolution measurement of cortical extravascular (tissue) pO(2), opening many possibilities for functional metabolic brain studies.

Two-photon high-resolution measurement of partial pressure of oxygen in cerebral vasculature and tissue

Science.gov (United States)

Sakadžić, Sava; Roussakis, Emmanuel; Yaseen, Mohammad A.; Mandeville, Emiri T.; Srinivasan, Vivek J.; Arai, Ken; Ruvinskaya, Svetlana; Devor, Anna; Lo, Eng H.; Vinogradov, Sergei A.; Boas, David A.

2010-01-01

The ability to measure oxygen partial pressure (pO2) with high temporal and spatial resolution in three dimensions is crucial for understanding oxygen delivery and consumption in normal and diseased brain. Among existing pO2 measurement methods, phosphorescence quenching is optimally suited for the task. However, previous attempts to couple phosphorescence with two-photon laser scanning microscopy have faced substantial difficulties because of extremely low two-photon absorption cross-sections of conventional phosphorescent probes. Here, we report the first practical in vivo two-photon high-resolution pO2 measurements in small rodents’ cortical microvasculature and tissue, made possible by combining an optimized imaging system with a two-photon-enhanced phosphorescent nanoprobe. The method features a measurement depth of up to 250 µm, sub-second temporal resolution and requires low probe concentration. Most importantly, the properties of the probe allowed for the first direct high-resolution measurement of cortical extravascular (tissue) pO2, opening numerous possibilities for functional metabolic brain studies. PMID:20693997

Time resolution performance studies of contemporary high speed photomultipliers

International Nuclear Information System (INIS)

Leskovar, B.; Lo, C.C.

1978-01-01

The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single phtoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems. 16 refs

Electron microscopy at atomic resolution

Energy Technology Data Exchange (ETDEWEB)

Gronsky, R.

1983-11-01

The direct imaging of atomic structure in solids has become increasingly easier to accomplish with modern transmission electron microscopes, many of which have an information retrieval limit near 0.2 nm point resolution. Achieving better resolution, particularly with any useful range of specimen tilting, requires a major design effort. This presentation describes the new Atomic Resolution Microscope (ARM), recently put into operation at the Lawrence Berkeley Laboratory. Capable of 0.18 nm or better interpretable resolution over a voltage range of 400 kV to 1000 kV with +- 40/sup 0/ biaxial specimen tilting, the ARM features a number of new electron-optical and microprocessor-control designs. These are highlighted, and its atomic resolution performance demonstrated for a selection of inorganic crystals.

Electron microscopy at atomic resolution

International Nuclear Information System (INIS)

Gronsky, R.

1983-11-01

The direct imaging of atomic structure in solids has become increasingly easier to accomplish with modern transmission electron microscopes, many of which have an information retrieval limit near 0.2 nm point resolution. Achieving better resolution, particularly with any useful range of specimen tilting, requires a major design effort. This presentation describes the new Atomic Resolution Microscope (ARM), recently put into operation at the Lawrence Berkeley Laboratory. Capable of 0.18 nm or better interpretable resolution over a voltage range of 400 kV to 1000 kV with +- 40 0 biaxial specimen tilting, the ARM features a number of new electron-optical and microprocessor-control designs. These are highlighted, and its atomic resolution performance demonstrated for a selection of inorganic crystals

High resolution wind measurements for offshore wind energy development

Science.gov (United States)

Nghiem, Son Van (Inventor); Neumann, Gregory (Inventor)

2013-01-01

A method, apparatus, system, article of manufacture, and computer readable storage medium provide the ability to measure wind. Data at a first resolution (i.e., low resolution data) is collected by a satellite scatterometer. Thin slices of the data are determined. A collocation of the data slices are determined at each grid cell center to obtain ensembles of collocated data slices. Each ensemble of collocated data slices is decomposed into a mean part and a fluctuating part. The data is reconstructed at a second resolution from the mean part and a residue of the fluctuating part. A wind measurement is determined from the data at the second resolution using a wind model function. A description of the wind measurement is output.

Using elastic peak electron spectroscopy for enhanced depth resolution in sputter profiling

International Nuclear Information System (INIS)

Hofmann, S.; Kesler, V.

2002-01-01

Elastic peak electron spectroscopy (EPES) is an alternative to AES in sputter depth profiling of thin film structures. In contrast to AES, EPES depth profiling is not influenced by chemical effects. The high count rate ensures a good signal to noise ratio, that is lower measurement times and/or higher precision. In addition, because of the elastically scattered electrons travel twice through the sample, the effective escape depth is reduced, an important factor for the depth resolution function. Thus, the depth resolution is increased. EPES depth profiling was successfully applied to a Ge/Si multilayer structure. For an elastic peak energy of 1.0 keV the information depth is considerably lower (0.8 nm) as compared to the Ge (LMM, 1147 eV) peak (1.6 nm) used in AES depth profiling, resulting in a respectively improved depth resolution for EPES profiling under otherwise similar profiling conditions. EPES depth profiling is successfully applied to measure small diffusion lengths at Ge/Si interfaces of the order of 1 nm. (Authors)

State of the art in atomic resolution off-axis electron holography

International Nuclear Information System (INIS)

Linck, Martin; Freitag, Bert; Kujawa, Stephan; Lehmann, Michael; Niermann, Tore

2012-01-01

As proposed by Hannes Lichte, to resolve structure–property relations not only the question “Which atom is where?” but also the question “Which fields are around?” has to be answered. High-resolution off-axis electron holography opens up an access to these key questions in that it allows accessing the complete exit-wave of the object provided within the information limit of the microscope, i.e. amplitude and phase including atomic details such as position and species, and moreover, information about large area electric potentials and magnetic fields, which a conventional transmission electron microscope is blind for—also when using a Cs-corrector. For an excellent object exit-wave reconstruction, special care has to be taken on the hologram quality, i.e. interference fringe contrast and electron dose. Severe restrictions are given to signal resolution by the limited brightness of the electron source. Utilizing a new high-brightness Schottky field electron emitter in a state-of-the-art transmission electron microscope operated at 300 kV, the phase signal resolution at atomic resolution can significantly be enhanced. An improvement by at least a factor of 2.88 compared to the most recently reported single hologram at atomic resolution is found. To proof the applicability of this setup to real materials science problems, a grain boundary of gold has been investigated holographically. -- Highlights: ► Impact of the brightness on the reconstructed signal in electron holography. ► Factor 2.8 gain in signal quality by setup with a high brightness electron gun. ► Investigation of a grain boundary in gold with a state-of-the-art holography setup. ► A-posteriori aberration fine-tuning for true one Angstrom resolution in the object wave. ► Mistilt analysis on the atomic scale by numerical wave optics.

High resolution electron microscopy of a small crack at the superficial layer of enamel.

Science.gov (United States)

Hayashi, Y

1994-12-01

A small enamel crack was investigated using a high resolution electron microscope. The inside of the crack was filled with aggregates of irregularly oriented plate-like crystals. Amorphous mineral deposits were observed among these aggregates at a low magnification. Selected area electron diffractions indicated that the plate-like crystals consisted of hydroxyapatite (OH-AP), and that the amorphous mineral deposits were a mixture of OH-AP and whitlockite. These findings indicate that this crack may have been formed by occlusal and/or masticatory stress, and that a natural occlusion might occur through mineral deposition at the small crack such as in this case.

Time resolution performance studies of contemporary high speed photomultipliers

International Nuclear Information System (INIS)

Leskovar, B.; Lo, C.C.

1977-01-01

The time resolution capabilities of prototype microchannel plate and static crossed-field photomultipliers have been investigated. Measurements were made of electron transit time, rise time, time response, single photoelectron time spread and multiphotoelectron time spread for LEP HR350 proximity focused high gain curved microchannel plate and VPM-154A/1.6L static crossed-field photomultipliers. The experimental data have been compared with results obtained with conventionally designed RCS 8850 and C31024 high speed photomultipliers. Descriptions are given of both the measuring techniques and the measuring systems

Ultra-high resolution protein crystallography

International Nuclear Information System (INIS)

Takeda, Kazuki; Hirano, Yu; Miki, Kunio

2010-01-01

Many protein structures have been determined by X-ray crystallography and deposited with the Protein Data Bank. However, these structures at usual resolution (1.5< d<3.0 A) are insufficient in their precision and quantity for elucidating the molecular mechanism of protein functions directly from structural information. Several studies at ultra-high resolution (d<0.8 A) have been performed with synchrotron radiation in the last decade. The highest resolution of the protein crystals was achieved at 0.54 A resolution for a small protein, crambin. In such high resolution crystals, almost all of hydrogen atoms of proteins and some hydrogen atoms of bound water molecules are experimentally observed. In addition, outer-shell electrons of proteins can be analyzed by the multipole refinement procedure. However, the influence of X-rays should be precisely estimated in order to derive meaningful information from the crystallographic results. In this review, we summarize refinement procedures, current status and perspectives for ultra high resolution protein crystallography. (author)

High-Resolution Wind Measurements for Offshore Wind Energy Development

Science.gov (United States)

Nghiem, Son V.; Neumann, Gregory

2011-01-01

A mathematical transform, called the Rosette Transform, together with a new method, called the Dense Sampling Method, have been developed. The Rosette Transform is invented to apply to both the mean part and the fluctuating part of a targeted radar signature using the Dense Sampling Method to construct the data in a high-resolution grid at 1-km posting for wind measurements over water surfaces such as oceans or lakes.

All-inkjet-printed flexible electronics fabrication on a polymer substrate by low-temperature high-resolution selective laser sintering of metal nanoparticles

International Nuclear Information System (INIS)

Ko, Seung H; Pan Heng; Grigoropoulos, Costas P; Luscombe, Christine K; Frechet, Jean M J; Poulikakos, Dimos

2007-01-01

All-printed electronics is the key technology to ultra-low-cost, large-area electronics. As a critical step in this direction, we demonstrate that laser sintering of inkjet-printed metal nanoparticles enables low-temperature metal deposition as well as high-resolution patterning to overcome the resolution limitation of the current inkjet direct writing processes. To demonstrate this process combined with the implementation of air-stable carboxylate-functionalized polythiophenes, high-resolution organic transistors were fabricated in ambient pressure and room temperature without utilizing any photolithographic steps or requiring a vacuum deposition process. Local thermal control of the laser sintering process could minimize the heat-affected zone and the thermal damage to the substrate and further enhance the resolution of the process. This local nanoparticle deposition and energy coupling enable an environmentally friendly and cost-effective process as well as a low-temperature manufacturing sequence to realize large-area, flexible electronics on polymer substrates

On the optimum resolution of transmission-electron backscattered diffraction (t-EBSD)

Energy Technology Data Exchange (ETDEWEB)

Bremen, R. van; Ribas Gomes, D.; Jeer, L.T.H. de; Ocelík, V., E-mail: v.ocelik@rug.nl; De Hosson, J.Th.M.

2016-01-15

The work presented aims at determining the optimum physical resolution of the transmission-electron backscattered diffraction (t-EBSD) technique. The resolution depends critically on intrinsic factors such as the density, atomic number and thickness of the specimen but also on the extrinsic experimental set-up of the electron beam voltage, specimen tilt and detector position. In the present study, the so-called physical resolution of a typical t-EBSD set-up was determined with the use of Monte Carlo simulations and confronted to experimental findings. In the case of a thin Au film of 20 nm, the best resolution obtained was 9 nm whereas for a 100 nm Au film the best resolution was 66 nm. The precise dependence of resolution on thickness was found to vary differently depending on the specific elements involved. This means that the resolution of each specimen should be determined individually. Experimentally the median probe size of the t-EBSD for a 140 nm thick AuAg specimen was measured to be 87 nm. The first and third quartiles of the probe size measurements were found to be 60 nm and 118 nm. Simulation of this specimen resulted in a resolution of 94 nm which fits between these quartiles. - Highlights: • Intrinsic and extrinsic factors affecting resolution of t-EBSD are determined and characterized. • Distinction between resolutions of transmitted and detected electrons is determined. • The simulated results are confirmed experimentally on 140 nm thick AuAg foil.

Fluorescence photooxidation with eosin: a method for high resolution immunolocalization and in situ hybridization detection for light and electron microscopy

Science.gov (United States)

1994-01-01

A simple method is described for high-resolution light and electron microscopic immunolocalization of proteins in cells and tissues by immunofluorescence and subsequent photooxidation of diaminobenzidine tetrahydrochloride into an insoluble osmiophilic polymer. By using eosin as the fluorescent marker, a substantial improvement in sensitivity is achieved in the photooxidation process over other conventional fluorescent compounds. The technique allows for precise correlative immunolocalization studies on the same sample using fluorescence, transmitted light and electron microscopy. Furthermore, because eosin is smaller in size than other conventional markers, this method results in improved penetration of labeling reagents compared to gold or enzyme based procedures. The improved penetration allows for three-dimensional immunolocalization using high voltage electron microscopy. Fluorescence photooxidation can also be used for high resolution light and electron microscopic localization of specific nucleic acid sequences by in situ hybridization utilizing biotinylated probes followed by an eosin-streptavidin conjugate. PMID:7519623

High resolution transmission electron microscopic study of nanoporous carbon consisting of curved single graphite sheets

International Nuclear Information System (INIS)

Bourgeois, L.N.; Bursill, L.A.

1997-01-01

A high resolution transmission electron microscopic study of a nanoporous carbon rich in curved graphite monolayers is presented. Observations of very thin regions. including the effect of tilting the specimen with respect to the electron beam, are reported. The initiation of single sheet material on an oriented graphite substrate is also observed. When combined with image simulations and independent measurements of the density (1.37g cm -3 ) and sp 3 /sp 2 +sp 2 bonding fraction (0.16), these observations suggest that this material is a two phase mixture containing a relatively low density aggregation of essentially capped single shells like squat nanotubes and polyhedra, plus a relatively dense 'amorphous' carbon structure which may be described using a random-Schwarzite model. Some negatively-curved sheets were also identified in the low density phase. Finally, some discussion is offered regarding the growth mechanisms responsible for this nanoporous carbon and its relationship with the structures of amorphous carbons across a broad range of densities, porosities and sp 3 /sp 2 +sp 3 bonding fractions

High resolution simultaneous measurements of airborne radionuclides

International Nuclear Information System (INIS)

Abe, T.; Yamaguchi, Y.; Tanaka, K.; Komura, K.

2006-01-01

High resolution (2-3 hrs) simultaneous measurements of airborne radionuclides, 212 Pb, 210 Pb and 7 Be, have been performed by using extremely low background Ge detectors at Ogoya Underground Laboratory. We have measured above radionuclides at three monitoring points viz, 1) Low Level Radioactivity Laboratory (LLRL) Kanazawa University, 2) Shishiku Plateau (640 m MSL) located about 8 km from LLRL to investigate vertical difference of activity levels, and 3) Hegura Island (10 m MSL) located about 50 km from Noto Peninsula in the Sea of Japan to evaluate the influences of Asian continent or mainland of Japan on the variation to the activity levels. Variations of short-lived 212 Pb concentration showed noticeable time lags between at LLRL and at Shishiku Plateau. These time lags might be caused by change of height of a planetary boundary layer. On the contrary, variations of long-lived 210 Pb and 7 Be showed simultaneity at three locations because of homogeneity of these concentrations all over the area. (author)

Electron drift time in silicon drift detectors: A technique for high precision measurement of electron drift mobility

International Nuclear Information System (INIS)

Castoldi, A.; Rehak, P.

1995-01-01

This paper presents a precise absolute measurement of the drift velocity and mobility of electrons in high resistivity silicon at room temperature. The electron velocity is obtained from the differential measurement of the drift time of an electron cloud in a silicon drift detector. The main features of the transport scheme of this class of detectors are: the high uniformity of the electron motion, the transport of the signal electrons entirely contained in the high-purity bulk, the low noise timing due to the very small anode capacitance (typical value 100 fF), and the possibility to measure different drift distances, up to the wafer diameter, in the same semiconductor sample. These features make the silicon drift detector an optimal device for high precision measurements of carrier drift properties. The electron drift velocity and mobility in a 10 kΩ cm NTD n-type silicon wafer have been measured as a function of the electric field in the range of possible operation of a typical drift detector (167--633 V/cm). The electron ohmic mobility is found to be 1394 cm 2 /V s. The measurement precision is better than 1%. copyright 1995 American Institute of Physics

Emittance measurement for high-brightness electron guns

International Nuclear Information System (INIS)

Kobayashi, H.; Kurihara, T.; Sato, I.; Asami, A.; Yamazaki, Y.; Otani, S.; Ishizawa, Y.

1992-01-01

An emittance measurement system based on a high-precision pepper-pot technique has been developed for electron guns with low emittance of around πmm-mrad. Electron guns with a 1 mmφ cathode, the material of which is impregnated tungsten or single-crystal lanthanum hexaboride (La 1-x Ce x )B 6 , have been developed. The performance has been evaluated by putting stress on cathode roughness, which gives rise to an angular divergence, according to the precise emittance measurement system. A new type of cathode holder, which is a modified version of the so called Vogel type, was developed and the beam uniformity has been improved. (Author) 5 figs., tab., 9 refs

Dynamic frequency-domain interferometer for absolute distance measurements with high resolution

International Nuclear Information System (INIS)

Weng, Jidong; Liu, Shenggang; Ma, Heli; Tao, Tianjiong; Wang, Xiang; Liu, Cangli; Tan, Hua

2014-01-01

A unique dynamic frequency-domain interferometer for absolute distance measurement has been developed recently. This paper presents the working principle of the new interferometric system, which uses a photonic crystal fiber to transmit the wide-spectrum light beams and a high-speed streak camera or frame camera to record the interference stripes. Preliminary measurements of harmonic vibrations of a speaker, driven by a radio, and the changes in the tip clearance of a rotating gear wheel show that this new type of interferometer has the ability to perform absolute distance measurements both with high time- and distance-resolution

Dynamic frequency-domain interferometer for absolute distance measurements with high resolution

Science.gov (United States)

Weng, Jidong; Liu, Shenggang; Ma, Heli; Tao, Tianjiong; Wang, Xiang; Liu, Cangli; Tan, Hua

2014-11-01

A unique dynamic frequency-domain interferometer for absolute distance measurement has been developed recently. This paper presents the working principle of the new interferometric system, which uses a photonic crystal fiber to transmit the wide-spectrum light beams and a high-speed streak camera or frame camera to record the interference stripes. Preliminary measurements of harmonic vibrations of a speaker, driven by a radio, and the changes in the tip clearance of a rotating gear wheel show that this new type of interferometer has the ability to perform absolute distance measurements both with high time- and distance-resolution.

Optical circular deflector with attosecond resolution for ultrashort electron beam

Directory of Open Access Journals (Sweden)

Zhen Zhang

2017-05-01

Full Text Available A novel method using high-power laser as a circular deflector is proposed for the measurement of femtosecond (fs and sub-fs electron beam. In the scheme, the electron beam interacts with a laser pulse operating in a radially polarized doughnut mode (TEM_{01^{*}} in a helical undulator, generating angular kicks along the beam in two directions at the same time. The phase difference between the two angular kicks makes the beam form a ring after a propagation section with appropriate phase advance, which can reveal the current profile of the electron beam. Detailed theoretical analysis of the method and numerical results with reasonable parameters are both presented. It is shown that the temporal resolution can reach up to ∼100 attosecond, which is a significant improvement for the diagnostics of ultrashort electron beam.

High-resolution photocurrent microscopy using near-field cathodoluminescence of quantum dots

Directory of Open Access Journals (Sweden)

Heayoung P. Yoon

2013-06-01

Full Text Available We report a fast, versatile photocurrent imaging technique to visualize the local photo response of solar energy devices and optoelectronics using near-field cathodoluminescence (CL from a homogeneous quantum dot layer. This approach is quantitatively compared with direct measurements of high-resolution Electron Beam Induced Current (EBIC using a thin film solar cell (n-CdS / p-CdTe. Qualitatively, the observed image contrast is similar, showing strong enhancement of the carrier collection efficiency at the p-n junction and near the grain boundaries. The spatial resolution of the new technique, termed Q-EBIC (EBIC using quantum dots, is determined by the absorption depth of photons. The results demonstrate a new method for high-resolution, sub-wavelength photocurrent imaging measurement relevant for a wide range of applications.

High Spectral Resolution Lidar Based on a Potassium Faraday Dispersive Filter for Daytime Temperature Measurement

Directory of Open Access Journals (Sweden)

Abo Makoto

2016-01-01

Full Text Available In this paper, a new high-spectral-resolution lidar technique is proposed for measuring the profiles of atmospheric temperature in daytime. Based on the theory of high resolution Rayleigh scattering, the feasibility and advantages of using potassium (K Faraday dispersive optical filters as blocking filters for measuring atmospheric temperature are demonstrated with a numerical simulation. It was found that temperature profiles could be measured within 1K error for the height of 9 km with a 500 m range resolution in 60 min by using laser pulses with 1mJ/pulse and 1 kHz, and a 50 cm diameter telescope. Furthermore, we are developing compact pulsed laser system for temperature lidar transmitter.

Fallspeed measurement and high-resolution multi-angle photography of hydrometeors in freefall

OpenAIRE

T. J. Garrett; C. Fallgatter; K. Shkurko; D. Howlett

2012-01-01

We describe here a new instrument for imaging hydrometeors in freefall. The Multi-Angle Snowflake Camera (MASC) captures high resolution photographs of hydrometeors from three angles while simultaneously measuring their fallspeed. Based on the stereoscopic photographs captured over the two months of continuous measurements obtained at a high altitude location within the Wasatch Front in Utah, we derive statistics for fallspeed, hydrometeor size, shape, orientation and aspect ratio. From a sel...

Electron beam excitation assisted optical microscope with ultra-high resolution.

Science.gov (United States)

Inami, Wataru; Nakajima, Kentaro; Miyakawa, Atsuo; Kawata, Yoshimasa

2010-06-07

We propose electron beam excitation assisted optical microscope, and demonstrated its resolution higher than 50 nm. In the microscope, a light source in a few nanometers size is excited by focused electron beam in a luminescent film. The microscope makes it possible to observe dynamic behavior of living biological specimens in various surroundings, such as air or liquids. Scan speed of the nanometric light source is faster than that in conventional near-field scanning optical microscopes. The microscope enables to observe optical constants such as absorption, refractive index, polarization, and their dynamic behavior on a nanometric scale. The microscope opens new microscopy applications in nano-technology and nano-science.

The high-resolution extraterrestrial solar spectrum (QASUMEFTS determined from ground-based solar irradiance measurements

Directory of Open Access Journals (Sweden)

J. Gröbner

2017-09-01

Full Text Available A high-resolution extraterrestrial solar spectrum has been determined from ground-based measurements of direct solar spectral irradiance (SSI over the wavelength range from 300 to 500 nm using the Langley-plot technique. The measurements were obtained at the Izaña Atmospheric Research Centre from the Agencia Estatal de Meteorología, Tenerife, Spain, during the period 12 to 24 September 2016. This solar spectrum (QASUMEFTS was combined from medium-resolution (bandpass of 0.86 nm measurements of the QASUME (Quality Assurance of Spectral Ultraviolet Measurements in Europe spectroradiometer in the wavelength range from 300 to 500 nm and high-resolution measurements (0.025 nm from a Fourier transform spectroradiometer (FTS over the wavelength range from 305 to 380 nm. The Kitt Peak solar flux atlas was used to extend this high-resolution solar spectrum to 500 nm. The expanded uncertainties of this solar spectrum are 2 % between 310 and 500 nm and 4 % at 300 nm. The comparison of this solar spectrum with solar spectra measured in space (top of the atmosphere gave very good agreements in some cases, while in some other cases discrepancies of up to 5 % were observed. The QASUMEFTS solar spectrum represents a benchmark dataset with uncertainties lower than anything previously published. The metrological traceability of the measurements to the International System of Units (SI is assured by an unbroken chain of calibrations leading to the primary spectral irradiance standard of the Physikalisch-Technische Bundesanstalt in Germany.

Compact high-resolution echelle-AOTF NIR spectrometer for atmospheric measurements

Science.gov (United States)

Korablev, Oleg I.; Bertaux, Jean-Loup; Vinogradov, Imant I.; Kalinnikov, Yurii K.; Nevejans, D.; Neefs, E.; Le Barbu, T.; Durry, G.

2017-11-01

A new concept of a high-resolution near-IR spectrometer consisting of an echelle grating combined with an acousto-optic tunable filter (AOTF) for separation of diffraction orders, is developed for space-borne studies of planetary atmospheres. A compact design with no moving parts within the mass budget of 3-5 kg allows to reach the resolving power λ/Δλ of 20000-30000. Only a small piece of spectrum in high diffraction orders can be measured at a time, but thanks to flexibility of the AOTF electrical tuning, such pieces of spectrum can be measured randomly and rapidly within the spectral range. This development can be used for accurate measurements of important atmospheric gases, such as CO2 in terrestrial atmosphere, isotopic ratios and minor gases. A spectrometer, based on this principle, SOIR (Solar Occultation InfraRed) is being built for Venus Express (2005) ESA mission. Instruments based on this principle have high potential for the studies of the Earth, in particular for measurements of isotopes of water in the lower atmosphere, either in solar occultation profiling (tangent altitude <10 km), or observing solar glint for integral quantities of the components. Small size of hardware makes them ideal for micro-satellites, which are now agile enough to provide necessary pointing for solar occultation or glint observations. Also, the atmosphere of Mars has never been observed at local scales with such a high spectral resolution. A laboratory prototype consisting of 275-mm echelle spectrometer with Hamamatsu InGaAs 512-pixel linear array and the AOTF has demonstrated λ/Δλ≍30000 in the spectral range of 1-1.7 μm. The next set up, covering the spectral ranges of 1-1.7 μm and 2.3-4.3 μm, and the Venus Express SOIR are briefly discussed.

High-resolution broadband terahertz spectroscopy via electronic heterodyne detection of photonically generated terahertz frequency comb.

Science.gov (United States)

Pavelyev, D G; Skryl, A S; Bakunov, M I

2014-10-01

We report an alternative approach to the terahertz frequency-comb spectroscopy (TFCS) based on nonlinear mixing of a photonically generated terahertz pulse train with a continuous wave signal from an electronic synthesizer. A superlattice is used as a nonlinear mixer. Unlike the standard TFCS technique, this approach does not require a complex double-laser system but retains the advantages of TFCS-high spectral resolution and wide bandwidth.

Design of a fusion reaction-history measurement system with high temporal resolution

International Nuclear Information System (INIS)

Peng Xiaoshi; Wang Feng; Liu Shenye; Jiang Xiaohua; Tang Qi

2010-01-01

In order to accurately measure the history of fusion reaction for experimental study of inertial confinement fusion, we advance the design of a fusion reaction-history measurement system with high temporal resolution. The diagnostic system is composed of plastic scintillator and nose cone, an optical imaging system and the system of optic streak camera. Analyzing the capability of the system indicated that the instrument measured fusion reaction history at temporal resolution as low as 55ps and 40ps correspond to 2.45MeV DD neutrons and 14.03MeV DT neutrons. The instrument is able to measure the fusion reaction history at yields 1.5 x 10 9 DD neutrons, about 4 x 10 8 DT neutrons are required for a similar quality signal. (authors)

Observations of silicon carbide by high resolution transmission electron microscopy

International Nuclear Information System (INIS)

Smith, D.J.; Jepps, N.W.; Page, T.F.

1978-01-01

High resolution transmission electron microscopy techniques, principally involving direct lattice imaging, have been used as part of a study of the crystallography and phase transformation mechanics of silicon carbide polytypes. In particular, the 3C (cubic) and 6H (hexagonal) polytypes have been examined together with partially transformed structural mixtures. Although direct observation of two-dimensional atomic structures was not possible at an operating voltage of 100 kV, considerable microstructural information has been obtained by careful choice of the experimental conditions. In particular, tilted beam observations of the 0.25 nm lattice fringes have been made in the 3C polytype for two different brace 111 brace plane arrays in order to study the dimensions and coherency of finely-twinned regions together with brace 0006 brace and brace 1 0 bar1 2 brace lattice images in the 6H polytype which allow the detailed stacking operations to be resolved. Lower resolution lattice images formed with axial illumination have also been used to study the nature of the 3C → 6H transformation and results are presented showing that the transformation interface may originate with fine twinning of the 3C structure followed by growth of the resultant 6H regions. Observations have been made of the detailed stepped structure of this interface together with the stacking fault distribution in the resultant 6H material. (author)

Linear versus non-linear structural information limit in high-resolution transmission electron microscopy

International Nuclear Information System (INIS)

Van Aert, S.; Chen, J.H.; Van Dyck, D.

2010-01-01

A widely used performance criterion in high-resolution transmission electron microscopy (HRTEM) is the information limit. It corresponds to the inverse of the maximum spatial object frequency that is linearly transmitted with sufficient intensity from the exit plane of the object to the image plane and is limited due to partial temporal coherence. In practice, the information limit is often measured from a diffractogram or from Young's fringes assuming a weak phase object scattering beyond the inverse of the information limit. However, for an aberration corrected electron microscope, with an information limit in the sub-angstrom range, weak phase objects are no longer applicable since they do not scatter sufficiently in this range. Therefore, one relies on more strongly scattering objects such as crystals of heavy atoms observed along a low index zone axis. In that case, dynamical scattering becomes important such that the non-linear and linear interaction may be equally important. The non-linear interaction may then set the experimental cut-off frequency observed in a diffractogram. The goal of this paper is to quantify both the linear and the non-linear information transfer in terms of closed form analytical expressions. Whereas the cut-off frequency set by the linear transfer can be directly related with the attainable resolution, information from the non-linear transfer can only be extracted using quantitative, model-based methods. In contrast to the historic definition of the information limit depending on microscope parameters only, the expressions derived in this paper explicitly incorporate their dependence on the structure parameters as well. In order to emphasize this dependence and to distinguish from the usual information limit, the expressions derived for the inverse cut-off frequencies will be referred to as the linear and non-linear structural information limit. The present findings confirm the well-known result that partial temporal coherence has

Development of a high-resolution cavity-beam position monitor

Directory of Open Access Journals (Sweden)

Yoichi Inoue

2008-06-01

Full Text Available We have developed a high-resolution cavity-beam position monitor (BPM to be used at the focal point of the ATF2, which is a test beam line that is now being built to demonstrate stable orbit control at ∼nanometer resolution. The design of the cavity structure was optimized for the Accelerator Test Facility (ATF beam in various ways. For example, the cavity has a rectangular shape in order to isolate two dipole modes in orthogonal directions, and a relatively thin gap that is less sensitive to trajectory inclination. A two stage homodyne mixer with highly sensitive electronics and phase-sensitive detection was also developed. Two BPM blocks, each containing two cavity BPMs, were installed in the existing ATF beam line using a rigid support frame. After testing the basic characteristics, we measured the resolution using three BPMs. The system demonstrated 8.7 nm position resolution over a dynamic range of 5  μm.

Development of a high-resolution cavity-beam position monitor

Science.gov (United States)

Inoue, Yoichi; Hayano, Hitoshi; Honda, Yosuke; Takatomi, Toshikazu; Tauchi, Toshiaki; Urakawa, Junji; Komamiya, Sachio; Nakamura, Tomoya; Sanuki, Tomoyuki; Kim, Eun-San; Shin, Seung-Hwan; Vogel, Vladimir

2008-06-01

We have developed a high-resolution cavity-beam position monitor (BPM) to be used at the focal point of the ATF2, which is a test beam line that is now being built to demonstrate stable orbit control at ˜nanometer resolution. The design of the cavity structure was optimized for the Accelerator Test Facility (ATF) beam in various ways. For example, the cavity has a rectangular shape in order to isolate two dipole modes in orthogonal directions, and a relatively thin gap that is less sensitive to trajectory inclination. A two stage homodyne mixer with highly sensitive electronics and phase-sensitive detection was also developed. Two BPM blocks, each containing two cavity BPMs, were installed in the existing ATF beam line using a rigid support frame. After testing the basic characteristics, we measured the resolution using three BPMs. The system demonstrated 8.7 nm position resolution over a dynamic range of 5μm.

High speed, High resolution terahertz spectrometers

International Nuclear Information System (INIS)

Kim, Youngchan; Yee, Dae Su; Yi, Miwoo; Ahn, Jaewook

2008-01-01

A variety of sources and methods have been developed for terahertz spectroscopy during almost two decades. Terahertz time domain spectroscopy (THz TDS)has attracted particular attention as a basic measurement method in the fields of THz science and technology. Recently, asynchronous optical sampling (AOS)THz TDS has been demonstrated, featuring rapid data acquisition and a high spectral resolution. Also, terahertz frequency comb spectroscopy (TFCS)possesses attractive features for high precision terahertz spectroscopy. In this presentation, we report on these two types of terahertz spectrometer. Our high speed, high resolution terahertz spectrometer is demonstrated using two mode locked femtosecond lasers with slightly different repetition frequencies without a mechanical delay stage. The repetition frequencies of the two femtosecond lasers are stabilized by use of two phase locked loops sharing the same reference oscillator. The time resolution of our terahertz spectrometer is measured using the cross correlation method to be 270 fs. AOS THz TDS is presented in Fig. 1, which shows a time domain waveform rapidly acquired on a 10ns time window. The inset shows a zoom into the signal with 100ps time window. The spectrum obtained by the fast Fourier Transformation (FFT)of the time domain waveform has a frequency resolution of 100MHz. The dependence of the signal to noise ratio (SNR)on the measurement time is also investigated

Study of a high-resolution, 3-D positioning cadmium zinc telluride detector for PET

Science.gov (United States)

Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

2011-01-01

This paper investigates the performance of 1 mm resolution Cadmium Zinc Telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3-D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06±0.39% at 511 keV throughout most the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44±0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78±0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes – as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system. PMID:21335649

Study of a high-resolution, 3D positioning cadmium zinc telluride detector for PET.

Science.gov (United States)

Gu, Y; Matteson, J L; Skelton, R T; Deal, A C; Stephan, E A; Duttweiler, F; Gasaway, T M; Levin, C S

2011-03-21

This paper investigates the performance of 1 mm resolution cadmium zinc telluride (CZT) detectors for positron emission tomography (PET) capable of positioning the 3D coordinates of individual 511 keV photon interactions. The detectors comprise 40 mm × 40 mm × 5 mm monolithic CZT crystals that employ a novel cross-strip readout with interspersed steering electrodes to obtain high spatial and energy resolution. The study found a single anode FWHM energy resolution of 3.06 ± 0.39% at 511 keV throughout most of the detector volume. Improved resolution is expected with properly shielded front-end electronics. Measurements made using a collimated beam established the efficacy of the steering electrodes in facilitating enhanced charge collection across anodes, as well as a spatial resolution of 0.44 ± 0.07 mm in the direction orthogonal to the electrode planes. Finally, measurements based on coincidence electronic collimation yielded a point spread function with 0.78 ± 0.10 mm FWHM, demonstrating 1 mm spatial resolution capability transverse to the anodes-as expected from the 1 mm anode pitch. These findings indicate that the CZT-based detector concept has excellent performance and shows great promise for a high-resolution PET system.

Hard x-ray monochromator with milli-electron volt bandwidth for high-resolution diffraction studies of diamond crystals

Energy Technology Data Exchange (ETDEWEB)

Stoupin, Stanislav; Shvyd' ko, Yuri; Shu Deming; Khachatryan, Ruben; Xiao, Xianghui; DeCarlo, Francesco; Goetze, Kurt; Roberts, Timothy; Roehrig, Christian; Deriy, Alexey [Advanced Photon Source, Argonne National Laboratory, Illinois 60439 (United States)

2012-02-15

We report on design and performance of a high-resolution x-ray monochromator with a spectral bandwidth of {Delta}E{sub X}{approx_equal} 1.5 meV, which operates at x-ray energies in the vicinity of the backscattering (Bragg) energy E{sub H} = 13.903 keV of the (008) reflection in diamond. The monochromator is utilized for high-energy-resolution diffraction characterization of diamond crystals as elements of advanced x-ray crystal optics for synchrotrons and x-ray free-electron lasers. The monochromator and the related controls are made portable such that they can be installed and operated at any appropriate synchrotron beamline equipped with a pre-monochromator.

Resolution and drift measurements on the Advanced Photon Source beam position monitors

International Nuclear Information System (INIS)

Chung, Y.; Kahana, E.

1994-01-01

The resolution and long-term drift of the Advanced Photon Source (APS) beam position monitor (BPM) electronics were measured using the charged particle beams in the ESRF storage ring with various beam current and configurations (single bunch, 8 and 16 equally spaced bunches, and 1/3-fill). The energy of the stored electrons was 6 GeV. The integrated BPM electronics system as used for this work is capable of measuring the beam position on a turn-by-turn basis, which can be accumulated for N turns (N = 2 n , n = 1, 2, ... , 11). Estimation of the BPM resolution apart from the low-frequency beam motion was made by measuring the standard deviation in the measured beam position with different Ns. The analysis of the results indicates a BPM resolution of 18/√ N [μm] for the APS storage ring, which is equivalent to 0.07 μm/√Hz. For the miniature insertion device BPM with 2.8 times higher sensitivity, the resolution will be 0.02 μm/√Hz. The long-term drift of the BPM electronics independent of the actual beam motion was measured at 2 μm/hr, which settled after approximately 1.5 hours. This drift can be attributed mainly to the temperature effect. Comparison of the results with the laboratory measurements shows good agreement. Implication of the BPM resolution limit on the proposed global and local beam position feedback systems for the APS storage ring will also be discussed

Depth of interaction resolution measurements for a high resolution PET detector using position sensitive avalanche photodiodes

International Nuclear Information System (INIS)

Yang Yongfeng; Dokhale, Purushottam A; Silverman, Robert W; Shah, Kanai S; McClish, Mickel A; Farrell, Richard; Entine, Gerald; Cherry, Simon R

2006-01-01

We explore dual-ended read out of LSO arrays with two position sensitive avalanche photodiodes (PSAPDs) as a high resolution, high efficiency depth-encoding detector for PET applications. Flood histograms, energy resolution and depth of interaction (DOI) resolution were measured for unpolished LSO arrays with individual crystal sizes of 1.0, 1.3 and 1.5 mm, and for a polished LSO array with 1.3 mm pixels. The thickness of the crystal arrays was 20 mm. Good flood histograms were obtained for all four arrays, and crystals in all four arrays can be clearly resolved. Although the amplitude of each PSAPD signal decreases as the interaction depth moves further from the PSAPD, the sum of the two PSAPD signals is essentially constant with irradiation depth for all four arrays. The energy resolutions were similar for all four arrays, ranging from 14.7% to 15.4%. A DOI resolution of 3-4 mm (including the width of the irradiation band which is ∼2 mm) was obtained for all the unpolished arrays. The best DOI resolution was achieved with the unpolished 1 mm array (average 3.5 mm). The DOI resolution for the 1.3 mm and 1.5 mm unpolished arrays was 3.7 and 4.0 mm respectively. For the polished array, the DOI resolution was only 16.5 mm. Summing the DOI profiles across all crystals for the 1 mm array only degraded the DOI resolution from 3.5 mm to 3.9 mm, indicating that it may not be necessary to calibrate the DOI response separately for each crystal within an array. The DOI response of individual crystals in the array confirms this finding. These results provide a detailed characterization of the DOI response of these PSAPD-based PET detectors which will be important in the design and calibration of a PET scanner making use of this detector approach

A high resolution portable spectroscopy system

International Nuclear Information System (INIS)

Kulkarni, C.P.; Vaidya, P.P.; Paulson, M.; Bhatnagar, P.V.; Pande, S.S.; Padmini, S.

2003-01-01

Full text: This paper describes the system details of a High Resolution Portable Spectroscopy System (HRPSS) developed at Electronics Division, BARC. The system can be used for laboratory class, high-resolution nuclear spectroscopy applications. The HRPSS consists of a specially designed compact NIM bin, with built-in power supplies, accommodating a low power, high resolution MCA, and on-board embedded computer for spectrum building and communication. A NIM based spectroscopy amplifier and a HV module for detector bias are integrated (plug-in) in the bin. The system communicates with a host PC via a serial link. Along-with a laptop PC, and a portable HP-Ge detector, the HRPSS offers a laboratory class performance for portable applications

Minimum detection limit and spatial resolution of thin-sample field-emission electron probe microanalysis

International Nuclear Information System (INIS)

Kubo, Yugo; Hamada, Kotaro; Urano, Akira

2013-01-01

The minimum detection limit and spatial resolution for a thinned semiconductor sample were determined by electron probe microanalysis (EPMA) using a Schottky field emission (FE) electron gun and wavelength dispersive X-ray spectrometry. Comparison of the FE-EPMA results with those obtained using energy dispersive X-ray spectrometry in conjunction with scanning transmission electron microscopy, confirmed that FE-EPMA is largely superior in terms of detection sensitivity. Thin-sample FE-EPMA is demonstrated as a very effective method for high resolution, high sensitivity analysis in a laboratory environment because a high probe current and high signal-to-noise ratio can be achieved. - Highlights: • Minimum detection limit and spatial resolution determined for FE-EPMA. • Detection sensitivity of FE-EPMA greatly superior to that of STEM-EDX. • Minimum detection limit and spatial resolution controllable by probe current

Averaging scheme for atomic resolution off-axis electron holograms.

Science.gov (United States)

Niermann, T; Lehmann, M

2014-08-01

All micrographs are limited by shot-noise, which is intrinsic to the detection process of electrons. For beam insensitive specimen this limitation can in principle easily be circumvented by prolonged exposure times. However, in the high-resolution regime several instrumental instabilities limit the applicable exposure time. Particularly in the case of off-axis holography the holograms are highly sensitive to the position and voltage of the electron-optical biprism. We present a novel reconstruction algorithm to average series of off-axis holograms while compensating for specimen drift, biprism drift, drift of biprism voltage, and drift of defocus, which all might cause problematic changes from exposure to exposure. We show an application of the algorithm utilizing also the possibilities of double biprism holography, which results in a high quality exit-wave reconstruction with 75 pm resolution at a very high signal-to-noise ratio. Copyright © 2014 Elsevier Ltd. All rights reserved.

Exciton diffusion coefficient measurement in ZnO nanowires under electron beam irradiation

Science.gov (United States)

Donatini, Fabrice; Pernot, Julien

2018-03-01

In semiconductor nanowires (NWs) the exciton diffusion coefficient can be determined using a scanning electron microscope fitted with a cathodoluminescence system. High spatial and temporal resolution cathodoluminescence experiments are needed to measure independently the exciton diffusion length and lifetime in single NWs. However, both diffusion length and lifetime can be affected by the electron beam bombardment during observation and measurement. Thus, in this work the exciton lifetime in a ZnO NW is measured versus the electron beam dose (EBD) via a time-resolved cathodoluminescence experiment with a temporal resolution of 50 ps. The behavior of the measured exciton lifetime is consistent with our recent work on the EBD dependence of the exciton diffusion length in similar NWs investigated under comparable SEM conditions. Combining the two results, the exciton diffusion coefficient in ZnO is determined at room temperature and is found constant over the full span of EBD.

In-beam measurement of the position resolution of a highly segmented coaxial germanium detector

International Nuclear Information System (INIS)

Descovich, M.; Lee, I.Y.; Fallon, P.; Cromaz, M.; Macchiavelli, A.O.; Radford, D.C.; Vetter, K.; Clark, R.M.; Deleplanque, M.A.; Stephens, F.S.; Ward, D.

2005-01-01

The position resolution of a highly segmented coaxial germanium detector was determined by analyzing the 2055keV γ-ray transition of Zr90 excited in a fusion-evaporation reaction. The high velocity of the Zr90 nuclei imparted large Doppler shifts. Digital analysis of the detector signals recovered the energy and position of individual γ-ray interactions. The location of the first interaction in the crystal was used to correct the Doppler energy shift. Comparison of the measured energy resolution with simulations implied a position resolution (root mean square) of 2mm in three-dimensions

Characterisation of phases in nanostructured, multilayered titanium alloys by analytical and high-resolution electron microscopy.

Science.gov (United States)

Czyrska-Filemonowicz, A; Buffat, P A

2009-01-01

Surface processing of a Ti-6Al-4V alloy led to a complex multilayered microstructure containing several phases of the Ni-Ti-P-Al-O system, which improves the mechanical and tribological surface properties. The microstructure, chemical and phase compositions of the hard layer formed on the surface were investigated by LM, XRD, SEM as well as analytical/high-resolution TEM, STEM, EDS, electron diffraction and FIB. Phase identification based on electron diffraction, HRTEM and EDS microanalysis revealed the presence of several binary and ternary phases in the system Ti-Ni-P, sometimes with partial substitution of Ti by Al. However some phases, mainly nanoparticles, still remain not identified satisfactorily. Electron microscopy techniques used for identification of phases present in surface multilayers and some practical limits to their routine application are reminded here.

Electron attachment to oxygen, ozone and other compounds of atmospheric relevance as studied with ultra-high energy resolution

International Nuclear Information System (INIS)

Maerk, T.D.; Matejcik, S.; Kiendler, A.; Cicman, P.; Senn, G.; Skalny, J.; Stampfli, P.; Illenberger, E.; Chu, Y.; Stamatovic, A.

1996-01-01

The processes of electron attachment to oxygen, ozone, ozone/oxygen cluster and oxygen cluster as well as other compounds of atmospheric relevance (CF 2 Cl 2 , CHCl 3 and CCl 3 Br) were studied with ultra-high energy resolution crossed beam technique

Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

International Nuclear Information System (INIS)

Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

2009-01-01

The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

Energy Technology Data Exchange (ETDEWEB)

Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

2009-07-01

The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

A high-resolution x-ray spectrometer for a kaon mass measurement

Energy Technology Data Exchange (ETDEWEB)

Phelan, Kevin, E-mail: kevin.phelan@oeaw.ac.at [Stefan Meyer Institute for Subatomic Physics of The Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna (Austria); Suzuki, Ken; Zmeskal, Johann [Stefan Meyer Institute for Subatomic Physics of The Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna (Austria); Tortorella, Daniele [Payr Engineering GmbH, Wiederschwing 25, A-9564 Patergassen (Austria); Bühler, Matthias; Hertrich, Theo [Low Temperature Solutions UG, Bahnhofstraße 21, D-85737 Ismaning (Germany)

2017-02-11

The ASPECT consortium (Adaptable Spectrometer Enabled by Cryogenic Technology) is currently constructing a generalised cryogenic platform for cryogenic detector work which will be able to accommodate a wide range of sensors. The cryogenics system is based on a small mechanical cooler with a further adiabatic demagnetisation stage and will work with cryogenic detectors at sub-Kelvin temperatures. The commercial aim of the consortium is to produce a compact, user-friendly device with an emphasis on reliability and portability which can easily be transported for specialised on-site work, such as beam-lines or telescope facilities. The cryogenic detector platform will accommodate a specially developed cryogenic sensor, either a metallic magnetic calorimeter or a magnetic penetration-depth thermometer. The detectors will be designed to work in various temperatures regions with an emphasis on optimising the various detector resolutions for specific temperatures. One resolution target is of about 10 eV at the energies range typically created in kaonic atoms experiments (soft x-ray energies). A following step will see the introduction of continuous, high-power, sub-Kelvin cooling which will bring the cryogenic basis for a high resolution spectrometer system to the market. The scientific goal of the project will produce an experimental set-up optimised for kaon-mass measurements performing high-resolution x-ray spectroscopy on a beam-line provided foreseeably by the J-PARC (Tokai, Japan) or DAΦNE (Frascati, Italy) facilities.

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

Science.gov (United States)

Aksoy, B.; Rehman, A.; Bayraktar, H.; Alaca, B. E.

2017-04-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µm are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

High-resolution spatiotemporal strain mapping reveals non-uniform deformation in micropatterned elastomers

International Nuclear Information System (INIS)

Aksoy, B; Alaca, B E; Rehman, A; Bayraktar, H

2017-01-01

Micropatterns are generated on a vast selection of polymeric substrates for various applications ranging from stretchable electronics to cellular mechanobiological systems. When these patterned substrates are exposed to external loading, strain field is primarily affected by the presence of microfabricated structures and similarly by fabrication-related defects. The capturing of such nonhomogeneous strain fields is of utmost importance in cases where study of the mechanical behavior with a high spatial resolution is necessary. Image-based non-contact strain measurement techniques are favorable and have recently been extended to scanning tunneling microscope and scanning electron microscope images for the characterization of mechanical properties of metallic materials, e.g. steel and aluminum, at the microscale. A similar real-time analysis of strain heterogeneity in elastomers is yet to be achieved during the entire loading sequence. The available measurement methods for polymeric materials mostly depend on cross-head displacement or precalibrated strain values. Thus, they suffer either from the lack of any real-time analysis, spatiotemporal distribution or high resolution in addition to a combination of these factors. In this work, these challenges are addressed by integrating a tensile stretcher with an inverted optical microscope and developing a subpixel particle tracking algorithm. As a proof of concept, the patterns with a critical dimension of 200 µ m are generated on polydimethylsiloxane substrates and strain distribution in the vicinity of the patterns is captured with a high spatiotemporal resolution. In the field of strain measurement, there is always a tradeoff between minimum measurable strain value and spatial resolution. Current noncontact techniques on elastomers can deliver a strain resolution of 0.001% over a minimum length of 5 cm. More importantly, inhomogeneities within this quite large region cannot be captured. The proposed technique can

High-resolution 3D dose distribution measured for two low-energy x-ray brachytherapy seeds: 125I and 103Pd

International Nuclear Information System (INIS)

Massillon-JL, G.; Minniti, R.; Mitch, M.G.; Soares, C.G.; Hearn, R.A.

2011-01-01

In this work, we have investigated the 3D absorbed dose distribution around 125 I and 103 Pd low-energy photon brachytherapy seeds using a high-spatial-resolution gel scanning system to address the current difficulty in measuring absorbed dose at close distances to these sources as a consequence of high dose rate gradient. A new version of BANG-gel coupled with a small format laser CT scanner has been used. Measurements were performed with 100 μm resolution in all dimensions. In particular, radial dose function and absorbed dose rate in the plane parallel to the sources longitudinal-axis were derived at radial distances smaller than or equal to 1 cm. In addition, the energy dependence was evaluated, finding that, within measurement uncertainties, the gel response is independent of the energy for energy photon values between 20 keV and 1250 keV. We have observed that at distances larger than 1.4 mm from the source, the delivered dose is similar to predictions from published Monte Carlo calculations (MC) for the 125 I seed. For distances between 1 mm and 3 mm, differences in magnitude and shape are significant for the 103 Pd seed, where an enhancement is observed. In the enhancement region, a difference of up to 70% in the radial dose function was obtained. Such observation suggests a contribution from other radionuclides emitting beta-particles or electrons, and not considered by MC. To understand the effect, spectrometry measurements were performed. A small contribution of 102 Rh/ 102m Rh radionuclide relative to 103 Pd was observed and its importance on the absorbed dose measured at close distances to the seed is time dependent and consequently, avoids reproducible measurements. Finally, the results obtained in this work underscore the importance of using high-spatial-resolution and water-equivalent detectors for measuring absorbed dose in low-energy photon radiation fields.

Construction of an apparatus for the investigation of inelastic electron scattering processes at high energy resolution and experimental determination of appearance energies of various atoms, molecules and small van-der-Waals clusters

International Nuclear Information System (INIS)

Winkler, C.

1993-03-01

A new experimental setup is presented, which enables the investigation of inelastic electron scattering processes at high energy resolution with dE n + cluster ions, n>3, is supported by these measurements

Resolution and drift measurements on the advanced photon source beam position monitor

International Nuclear Information System (INIS)

Chung, Y.; Kahana, E.

1995-01-01

The resolution and long-term drift of the Advanced Photon Source (APS) beam position monitor (BPM) electronics were measured using the charged particle beams in the ESRF storage ring with various beam current and configurations (single bunch, 8 and 16 equally spaced bunches, and 1/3-fill). The energy of the stored electrons was 6 GeV. The integrated BPM electronics system as used for this work is capable of measuring the beam position on a turn-by-turn basis, which can be accumulated for N turns (N=2 n , n=1,2,...,11) . Estimation of the BPM resolution apart from the low-frequency beam motion was made by measuring the standard deviation in the measured beam position with different Ns. The analysis of the results indicates a BPM resolution of 18/√N [μm] for the APS storage ring, which is equivalent to 0.07 μm/√Hz. For the miniature insertion device BPM with 2.8 times higher sensitivity, the resolution will be 0.02 μm/√Hz. The long-term drift of the BPM electronics independent of the actual beam motion was measured at 2 μm/hr, which settled after approximately 1.5 hours. This drift can be attributed mainly to the temperature effect. Comparison of the results with the laboratory measurements shows good agreement. Implication of the BPM resolution limit on the proposed global and local beam position feedback systems for the APS storage ring will also be discussed. copyright 1995 American Institute of Physics

Investigation of thin films, heterostructures and devices of ceramic superconductors by means of high-resolution electron microscopy

International Nuclear Information System (INIS)

Jia Chunlin.

1993-08-01

In this thesis a systematic study of the microstructure of YBa 2 Cu 3 O 7 thin films is presented by means of high-resolution electron microscopy (HREM). Most of the efforts are focused on the characterization of heterostructures of superconducting YBa 2 Cu 3 O 7 and non-superconducting PrBa 2 Cu 3 O 7 and on YBa 2 Cu 3 O 7 films deposited on step-edge substrates. These specially designed structures exhibit a great potential for the electronic application of high-Tc superconductors and for the investigation of the basic electric properties of the YBa 2 Cu 3 O 7 superconductor. (orig.) [de

Development of high speed integrated circuit for very high resolution timing measurements

International Nuclear Information System (INIS)

Mester, Christian

2009-10-01

A multi-channel high-precision low-power time-to-digital converter application specific integrated circuit for high energy physics applications has been designed and implemented in a 130 nm CMOS process. To reach a target resolution of 24.4 ps, a novel delay element has been conceived. This nominal resolution has been experimentally verified with a prototype, with a minimum resolution of 19 ps. To further improve the resolution, a new interpolation scheme has been described. The ASIC has been designed to use a reference clock with the LHC bunch crossing frequency of 40 MHz and generate all required timing signals internally, to ease to use within the framework of an LHC upgrade. Special care has been taken to minimise the power consumption. (orig.)

Development of high speed integrated circuit for very high resolution timing measurements

Energy Technology Data Exchange (ETDEWEB)

Mester, Christian

2009-10-15

A multi-channel high-precision low-power time-to-digital converter application specific integrated circuit for high energy physics applications has been designed and implemented in a 130 nm CMOS process. To reach a target resolution of 24.4 ps, a novel delay element has been conceived. This nominal resolution has been experimentally verified with a prototype, with a minimum resolution of 19 ps. To further improve the resolution, a new interpolation scheme has been described. The ASIC has been designed to use a reference clock with the LHC bunch crossing frequency of 40 MHz and generate all required timing signals internally, to ease to use within the framework of an LHC upgrade. Special care has been taken to minimise the power consumption. (orig.)

Specific, sensitive, high-resolution detection of protein molecules in eukaryotic cells using metal-tagging transmission electron microscopy

Science.gov (United States)

Risco, Cristina; Sanmartín-Conesa, Eva; Tzeng, Wen-Pin; Frey, Teryl K.; Seybold, Volker; de Groot, Raoul J.

2012-01-01

Summary More than any other methodology, transmission electron microscopy (TEM) has contributed to our understanding of the architecture and organization of cells. With current detection limits approaching atomic resolution, it will ultimately become possible to ultrastructurally image intracellular macromolecular assemblies in situ. Presently, however, methods to unambiguously identify proteins within the crowded environment of the cell’s interior are lagging behind. We describe a novel approach, metal-tagging TEM (METTEM) that allows detection of intracellular proteins in mammalian cells with high specificity, exceptional sensitivity and at molecular scale resolution. In live cells treated with gold salts, proteins bearing a small metal-binding tag will form 1-nm gold nanoclusters, readily detectable in electron micrographs. The applicability and strength of METTEM is demonstrated by a study of Rubella virus replicase and capsid proteins, which revealed virus-induced cell structures not seen before. PMID:22579245

Development of high-energy resolution inverse photoemission technique

International Nuclear Information System (INIS)

Asakura, D.; Fujii, Y.; Mizokawa, T.

2005-01-01

We developed a new inverse photoemission (IPES) machine based on a new idea to improve the energy resolution: off-plane Eagle mounting of the optical system in combination with dispersion matching between incoming electron and outgoing photon. In order to achieve dispersion matching, we have employed a parallel plate electron source and have investigated whether the electron beam is obtained as expected. In this paper, we present the principle and design of the new IPES method and report the current status of the high-energy resolution IPES machine

Rocket measurements of electron density irregularities during MAC/SINE

Science.gov (United States)

Ulwick, J. C.

1989-01-01

Four Super Arcas rockets were launched at the Andoya Rocket Range, Norway, as part of the MAC/SINE campaign to measure electron density irregularities with high spatial resolution in the cold summer polar mesosphere. They were launched as part of two salvos: the turbulent/gravity wave salvo (3 rockets) and the EISCAT/SOUSY radar salvo (one rocket). In both salvos meteorological rockets, measuring temperature and winds, were also launched and the SOUSY radar, located near the launch site, measured mesospheric turbulence. Electron density irregularities and strong gradients were measured by the rocket probes in the region of most intense backscatter observed by the radar. The electron density profiles (8 to 4 on ascent and 4 on descent) show very different characteristics in the peak scattering region and show marked spatial and temporal variability. These data are intercompared and discussed.

Coded aperture subreflector array for high resolution radar imaging

Science.gov (United States)

Lynch, Jonathan J.; Herrault, Florian; Kona, Keerti; Virbila, Gabriel; McGuire, Chuck; Wetzel, Mike; Fung, Helen; Prophet, Eric

2017-05-01

HRL Laboratories has been developing a new approach for high resolution radar imaging on stationary platforms. High angular resolution is achieved by operating at 235 GHz and using a scalable tile phased array architecture that has the potential to realize thousands of elements at an affordable cost. HRL utilizes aperture coding techniques to minimize the size and complexity of the RF electronics needed for beamforming, and wafer level fabrication and integration allow tiles containing 1024 elements to be manufactured with reasonable costs. This paper describes the results of an initial feasibility study for HRL's Coded Aperture Subreflector Array (CASA) approach for a 1024 element micromachined antenna array with integrated single-bit phase shifters. Two candidate electronic device technologies were evaluated over the 170 - 260 GHz range, GaN HEMT transistors and GaAs Schottky diodes. Array structures utilizing silicon micromachining and die bonding were evaluated for etch and alignment accuracy. Finally, the overall array efficiency was estimated to be about 37% (not including spillover losses) using full wave array simulations and measured device performance, which is a reasonable value at 235 GHz. Based on the measured data we selected GaN HEMT devices operated passively with 0V drain bias due to their extremely low DC power dissipation.

Performance of a high resolution cavity beam position monitor system

Science.gov (United States)

Walston, Sean; Boogert, Stewart; Chung, Carl; Fitsos, Pete; Frisch, Joe; Gronberg, Jeff; Hayano, Hitoshi; Honda, Yosuke; Kolomensky, Yury; Lyapin, Alexey; Malton, Stephen; May, Justin; McCormick, Douglas; Meller, Robert; Miller, David; Orimoto, Toyoko; Ross, Marc; Slater, Mark; Smith, Steve; Smith, Tonee; Terunuma, Nobuhiro; Thomson, Mark; Urakawa, Junji; Vogel, Vladimir; Ward, David; White, Glen

2007-07-01

It has been estimated that an RF cavity Beam Position Monitor (BPM) could provide a position measurement resolution of less than 1 nm. We have developed a high resolution cavity BPM and associated electronics. A triplet comprised of these BPMs was installed in the extraction line of the Accelerator Test Facility (ATF) at the High Energy Accelerator Research Organization (KEK) for testing with its ultra-low emittance beam. The three BPMs were each rigidly mounted inside an alignment frame on six variable-length struts which could be used to move the BPMs in position and angle. We have developed novel methods for extracting the position and tilt information from the BPM signals including a robust calibration algorithm which is immune to beam jitter. To date, we have demonstrated a position resolution of 15.6 nm and a tilt resolution of 2.1 μrad over a dynamic range of approximately ±20 μm.

High-resolution thermal expansion measurements under helium-gas pressure

Science.gov (United States)

Manna, Rudra Sekhar; Wolf, Bernd; de Souza, Mariano; Lang, Michael

2012-08-01

We report on the realization of a capacitive dilatometer, designed for high-resolution measurements of length changes of a material for temperatures 1.4 K ⩽ T ⩽ 300 K and hydrostatic pressure P ⩽ 250 MPa. Helium (4He) is used as a pressure-transmitting medium, ensuring hydrostatic-pressure conditions. Special emphasis has been given to guarantee, to a good approximation, constant-pressure conditions during temperature sweeps. The performance of the dilatometer is demonstrated by measurements of the coefficient of thermal expansion at pressures P ≃ 0.1 MPa (ambient pressure) and 104 MPa on a single crystal of azurite, Cu3(CO3)2(OH)2, a quasi-one-dimensional spin S = 1/2 Heisenberg antiferromagnet. The results indicate a strong effect of pressure on the magnetic interactions in this system.

Collective Thomson scattering measurements with high frequency resolution at TEXTOR

DEFF Research Database (Denmark)

Stejner Pedersen, Morten; Nielsen, Stefan Kragh; Korsholm, Søren Bang

2010-01-01

We discuss the development and first results of a receiver system for the collective Thomson scattering (CTS) diagnostic at TEXTOR with frequency resolution in the megahertz range or better. The improved frequency resolution expands the diagnostic range and utility of CTS measurements in general ...... and is a prerequisite for measurements of ion Bernstein wave signatures in CTS spectra. The first results from the new acquisition system are shown to be consistent with theory and with simultaneous measurements by the standard receiver system. © 2010 EURATOM...

High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

Directory of Open Access Journals (Sweden)

E. A. K. Ford

2007-06-01

Full Text Available Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

The measurement of the presampled MTF of a high spatial resolution neutron imaging system

International Nuclear Information System (INIS)

Cao, Raymond Lei; Biegalski, Steven R.

2007-01-01

A high spatial resolution neutron imaging device was developed at the Mark II TRIGA reactor at University of Texas at Austin. As the modulation transfer function (MTF) is recognized as a well-established parameter for evaluation of imaging system resolution, the aliasing associated with digital sampling adds complexity to its measurement. Aliasing is especially problematic when using a high spatial resolution micro-channel plate (MCP) neutron detector that has a pixel grid size similar to that of a CCD array. To compensate for the aliasing an angulated edge method was used to evaluate the neutron imaging facility, overcoming aliasing by obtaining an oversampled edge spread function (ESF). Baseline correction was applied to the ESF to remove the noticeable trends and the LSF was multiplied by Hann window to obtain a smoothed version of presampled MTF. The computing procedure is confirmed by visual inspection of a testing phantom; in addition, it is confirmed by comparison to the MTF measurement of a scintillation screen with a known MTF curve

Design and performance of a high resolution, low latency stripline beam position monitor system

Science.gov (United States)

Apsimon, R. J.; Bett, D. R.; Blaskovic Kraljevic, N.; Burrows, P. N.; Christian, G. B.; Clarke, C. I.; Constance, B. D.; Dabiri Khah, H.; Davis, M. R.; Perry, C.; Resta López, J.; Swinson, C. J.

2015-03-01

A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in particle accelerators and beam lines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. It consists of three stripline BPMs instrumented with analogue signal-processing electronics and a custom digitizer for logging the data. The design of the analogue processor units is presented in detail, along with measurements of the system performance. The processor latency is 15.6 ±0.1 ns . A single-pass beam position resolution of 291 ±10 nm has been achieved, using a beam with a bunch charge of approximately 1 nC.

Prospects of linear reconstruction in atomic resolution electron holographic tomography

International Nuclear Information System (INIS)

Krehl, Jonas; Lubk, Axel

2015-01-01

Tomography commonly requires a linear relation between the measured signal and the underlying specimen property; for Electron Holographic Tomography this is given by the Phase Grating Approximation (PGA). While largely valid at medium resolution, discrepancies arise at high resolution imaging conditions. We set out to investigate the artefacts that are produced if the reconstruction still assumes the PGA even with an atomic resolution tilt series. To forego experimental difficulties the holographic tilt series was simulated. The reconstructed electric potential clearly shows peaks at the positions of the atoms. These peaks have characterisitic deformations, which can be traced back to the defocus a particular atom has in the holograms of the tilt series. Exchanging an atom for one of a different atomic number results in a significant change in the reconstructed potential that is well contained within the atom's peak. - Highlights: • We simulate a holographic tilt series of a nanocrystal with atomic resolution. • Using PGA-based Holographic Tomography we reconstruct the atomic structure. • The reconstruction shows characteristic artefacts, chiefly caused by defocus. • Changing one atom's Z produces a well localised in the reconstruction

Prospects of linear reconstruction in atomic resolution electron holographic tomography

Energy Technology Data Exchange (ETDEWEB)

Krehl, Jonas, E-mail: Jonas.Krehl@triebenberg.de; Lubk, Axel

2015-03-15

Tomography commonly requires a linear relation between the measured signal and the underlying specimen property; for Electron Holographic Tomography this is given by the Phase Grating Approximation (PGA). While largely valid at medium resolution, discrepancies arise at high resolution imaging conditions. We set out to investigate the artefacts that are produced if the reconstruction still assumes the PGA even with an atomic resolution tilt series. To forego experimental difficulties the holographic tilt series was simulated. The reconstructed electric potential clearly shows peaks at the positions of the atoms. These peaks have characterisitic deformations, which can be traced back to the defocus a particular atom has in the holograms of the tilt series. Exchanging an atom for one of a different atomic number results in a significant change in the reconstructed potential that is well contained within the atom's peak. - Highlights: • We simulate a holographic tilt series of a nanocrystal with atomic resolution. • Using PGA-based Holographic Tomography we reconstruct the atomic structure. • The reconstruction shows characteristic artefacts, chiefly caused by defocus. • Changing one atom's Z produces a well localised in the reconstruction.

Electronic excitation of carbonyl sulphide (COS) by high-resolution vacuum ultraviolet photoabsorption and electron-impact spectroscopy in the energy region from 4 to 11 eV

Energy Technology Data Exchange (ETDEWEB)

Limão-Vieira, P., E-mail: plimaovieira@fct.unl.pt [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Department of Physics, Sophia University, Tokyo 102-8554 (Japan); Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Ferreira da Silva, F.; Almeida, D. [Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Hoshino, M.; Tanaka, H. [Department of Physics, Sophia University, Tokyo 102-8554 (Japan); Mogi, D. [Development and Marketing Department, New Products Development Division, Kanto Denka, Kogyo Co., Ltd., Chiyoda-ku, Tokyo 101-0063 (Japan); Tanioka, T. [Shibukawa Development Research Laboratory, New Products Development Division, Kanto Denka Kogyo Co., Ltd., Shibukawa City, Gunma 377-8513 (Japan); Mason, N. J. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Hoffmann, S. V. [ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Århus C (Denmark); Hubin-Franskin, M.-J.; Delwiche, J. [Départment de Chimie, Université de Liège, Institut de Chimie-Bât. B6C, allée de la Chimie 3, B-4000 Liège 1 (Belgium)

2015-02-14

The electronic state spectroscopy of carbonyl sulphide, COS, has been investigated using high resolution vacuum ultraviolet photoabsorption spectroscopy and electron energy loss spectroscopy in the energy range of 4.0–10.8 eV. The spectrum reveals several new features not previously reported in the literature. Vibronic structure has been observed, notably in the low energy absorption dipole forbidden band assigned to the (4π←3π) ({sup 1}Δ←{sup 1}Σ{sup +}) transition, with a new weak transition assigned to ({sup 1}Σ{sup −}←{sup 1}Σ{sup +}) reported here for the first time. The absolute optical oscillator strengths are determined for ground state to {sup 1}Σ{sup +} and {sup 1}Π transitions. Based on our recent measurements of differential cross sections for the optically allowed ({sup 1}Σ{sup +} and {sup 1}Π) transitions of COS by electron impact, the optical oscillator strength f{sub 0} value and integral cross sections (ICSs) are derived by applying a generalized oscillator strength analysis. Subsequently, ICSs predicted by the scaling are confirmed down to 60 eV in the intermediate energy region. The measured absolute photoabsorption cross sections have been used to calculate the photolysis lifetime of carbonyl sulphide in the upper stratosphere (20–50 km)

High resolution Transmission Electron Microscopy characterization of a milled oxide dispersion strengthened steel powder

Energy Technology Data Exchange (ETDEWEB)

Loyer-Prost, M., E-mail: marie.loyer-prost@cea.fr [DEN-Service de Recherches de Métallurgie Physique, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Merot, J.-S. [Laboratoire d’Etudes des Microstructures – UMR 104, CNRS/ONERA, BP72-29, Avenue de la Division Leclerc, 92 322, Châtillon (France); Ribis, J. [DEN-Service de Recherches de Métallurgie Appliquée, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Le Bouar, Y. [Laboratoire d’Etudes des Microstructures – UMR 104, CNRS/ONERA, BP72-29, Avenue de la Division Leclerc, 92 322, Châtillon (France); Chaffron, L. [DEN-Service de Recherches de Métallurgie Appliquée, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Legendre, F. [DEN-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France)

2016-10-15

Oxide Dispersion Strengthened (ODS) steels are promising materials for generation IV fuel claddings as their dense nano-oxide dispersion provides good creep and irradiation resistance. Even if they have been studied for years, the formation mechanism of these nano-oxides is still unclear. Here we report for the first time a High Resolution Transmission Electron Microscopy and Energy Filtered Transmission Electron Microscopy characterization of an ODS milled powder. It provides clear evidence of the presence of small crystalline nanoclusters (NCs) enriched in titanium directly after milling. Small NCs (<5 nm) have a crystalline structure and seem partly coherent with the matrix. They have an interplanar spacing close to the (011) {sub bcc} iron structure. They coexist with larger crystalline spherical precipitates of 15–20 nm in size. Their crystalline structure may be metastable as they are not consistent with any Y-Ti-O or Ti-O structure. Such detailed observations in the as-milled grain powder confirm a mechanism of Y, Ti, O dissolution in the ferritic matrix followed by a NC precipitation during the mechanical alloying process of ODS materials. - Highlights: • We observed an ODS ball-milled powder by high resolution transmission microscopy. • The ODS ball-milled powder exhibits a lamellar microstructure. • Small crystalline nanoclusters were detected in the milled ODS powder. • The nanoclusters in the ODS milled powder are enriched in titanium. • Larger NCs of 15–20 nm in size are, at least, partly coherent with the matrix.

Accurate and precise 40Ar/39Ar dating by high-resolution, multi-collection, mass spectrometry

DEFF Research Database (Denmark)

Storey, Michael; Rivera, Tiffany; Flude, Stephanie

New generation, high resolution, multi-collector noble gas mass spectrometers equipped with ion-counting electron multipliers provide opportunities for improved accuracy and precision in 40Ar/39Ar dating. Here we report analytical protocols and age cross-calibration studies using a NU-Instruments......New generation, high resolution, multi-collector noble gas mass spectrometers equipped with ion-counting electron multipliers provide opportunities for improved accuracy and precision in 40Ar/39Ar dating. Here we report analytical protocols and age cross-calibration studies using a NU......-Instruments multi-collector Noblesse noble gas mass spectrometer configured with a faraday detector and three ion-counting electron multipliers. The instrument has the capability to measure several noble gas isotopes simultaneously and to change measurement configurations instantaneously by the use of QUAD lenses...... (zoom optics). The Noblesse offer several advantages over previous generation noble gas mass spectrometers and is particularly suited for single crystal 40Ar/39Ar dating because of: (i) improved source sensitivity (ii) ion-counting electron multipliers, which have much lower signal to noise ratios than...

Measurement of Deuteron Tensor Polarization in Elastic Electron Scattering

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, Kenneth K. [Univ. of Maryland, College Park, MD (United States)

2000-01-01

Nuclear physics traces it roots back to the very beginning of the last century. The concept of the nuclear atom was introduced by Rutherford around 1910. The discovery of the neutron Chadwick in 1932 gave us the concept of two nucleons: the proton and the neutron. The Jlab electron accelerator with its intermediate energy high current continuous wave beam combined with the Hall C high resolution electron spectrometer and a deutron recoil polarimeter provided experiment E94018 with the opportunity to study the deuteron electomagnetic structure, in particular to measure the tensor polarization observable t₂₀, at high four momentum transfers than ever before. This dissertation presents results of JLab experiment E94018.

Measurements of the electron dose distribution near inhomogeneities using a plastic scintillation detector

International Nuclear Information System (INIS)

Wells, C.M.M.; Mackie, T.R.; Podgorsak, M.B.; Holmes, M.A.; Papanikolaou, N.; Reckwerdt, P.J.; Cygler, J.; Rogers, D.W.O.; Bielajew, A.F.; Schmidt, D.G.

1994-01-01

Accurate measurement of the electron dose distribution near an inhomogeneity is difficult with traditional dosimeters which themselves perturb the electron field. The authors tested the performance of a new high resolution, water-equivalent plastic scintillation detector which has ideal properties for this application. A plastic scintillation detector with a 1 mm diameter, 3 mm long cylindrical sensitive volume was used to measure the dose distributions behind standard benchmark inhomogeneities in water phantoms. The plastic scintillator material is more water equivalent than polystyrene in terms of its mass collision stopping power and mass scattering power. Measurements were performed for beams of electrons having initial energies of 6 and 18 MeV at depths from 0.2-4.2 cm behind the inhomogeneities. The detector reveals hot and cold spots behind heterogeneities at resolutions equivalent to typical film digitizer spot sizes. Plots of the dose distributions behind air, aluminum, lead, and formulations for cortical and inner bone-equivalent materials are presented. The plastic scintillation detector is suited for measuring the electron dose distribution near an inhomogeneity. 14 refs., 9 figs

An angle encoder for super-high resolution and super-high accuracy using SelfA

Science.gov (United States)

Watanabe, Tsukasa; Kon, Masahito; Nabeshima, Nobuo; Taniguchi, Kayoko

2014-06-01

Angular measurement technology at high resolution for applications such as in hard disk drive manufacturing machines, precision measurement equipment and aspherical process machines requires a rotary encoder with high accuracy, high resolution and high response speed. However, a rotary encoder has angular deviation factors during operation due to scale error or installation error. It has been assumed to be impossible to achieve accuracy below 0.1″ in angular measurement or control after the installation onto the rotating axis. Self-calibration (Lu and Trumper 2007 CIRP Ann. 56 499; Kim et al 2011 Proc. MacroScale; Probst 2008 Meas. Sci. Technol. 19 015101; Probst et al Meas. Sci. Technol. 9 1059; Tadashi and Makoto 1993 J. Robot. Mechatronics 5 448; Ralf et al 2006 Meas. Sci. Technol. 17 2811) and cross-calibration (Probst et al 1998 Meas. Sci. Technol. 9 1059; Just et al 2009 Precis. Eng. 33 530; Burnashev 2013 Quantum Electron. 43 130) technologies for a rotary encoder have been actively discussed on the basis of the principle of circular closure. This discussion prompted the development of rotary tables which achieve reliable and high accuracy angular verification. We apply these technologies for the development of a rotary encoder not only to meet the requirement of super-high accuracy but also to meet that of super-high resolution. This paper presents the development of an encoder with 221 = 2097 152 resolutions per rotation (360°), that is, corresponding to a 0.62″ signal period, achieved by the combination of a laser rotary encoder supplied by Magnescale Co., Ltd and a self-calibratable encoder (SelfA) supplied by The National Institute of Advanced Industrial Science & Technology (AIST). In addition, this paper introduces the development of a rotary encoder to guarantee ±0.03″ accuracy at any point of the interpolated signal, with respect to the encoder at the minimum resolution of 233, that is, corresponding to a 0.0015″ signal period after

High-Resolution Energy and Intensity Measurements with CVD Diamond at REX-ISOLDE

CERN Document Server

Griesmayer, E; Dobos, D; Wenander, F; Bergoz, J; Bayle, H; Frais-Kölbl, H; Leinweber, J; Aumeyr, T; CERN. Geneva. BE Department

2009-01-01

A novel beam instrumentation device for the HIE-REX (High In-tensity and Energy REX) upgrade has been developed and tested at the On-Line Isotope Mass Separator ISOLDE, located at the European Laboratory for Particle Physics (CERN). This device is based on CVD diamond detector technology and is used for measuring the beam intensity, particle counting and measuring the energy spectrum of the beam. An energy resolution of 0.6% was measured at a carbon ion energy of 22.8 MeV. This corresponds to an energy spread of ± 140 keV.

Low-cost, portable, robust and high-resolution single-camera stereo-DIC system and its application in high-temperature deformation measurements

Science.gov (United States)

Chi, Yuxi; Yu, Liping; Pan, Bing

2018-05-01

A low-cost, portable, robust and high-resolution single-camera stereo-digital image correlation (stereo-DIC) system for accurate surface three-dimensional (3D) shape and deformation measurements is described. This system adopts a single consumer-grade high-resolution digital Single Lens Reflex (SLR) camera and a four-mirror adaptor, rather than two synchronized industrial digital cameras, for stereo image acquisition. In addition, monochromatic blue light illumination and coupled bandpass filter imaging are integrated to ensure the robustness of the system against ambient light variations. In contrast to conventional binocular stereo-DIC systems, the developed pseudo-stereo-DIC system offers the advantages of low cost, portability, robustness against ambient light variations, and high resolution. The accuracy and precision of the developed single SLR camera-based stereo-DIC system were validated by measuring the 3D shape of a stationary sphere along with in-plane and out-of-plane displacements of a translated planar plate. Application of the established system to thermal deformation measurement of an alumina ceramic plate and a stainless-steel plate subjected to radiation heating was also demonstrated.

Electron-Scale Measurements of Magnetic Reconnection in Space

Science.gov (United States)

Burch, J. L.; Torbert, R. B.; Phan, T. D.; Chen, L.-J.; Moore, T. E.; Ergun, R. E.; Eastwood, J. P.; Gershman, D. J.; Cassak, P. A.; Argall, M. R.;

Design and performance of a high resolution, low latency stripline beam position monitor system

Directory of Open Access Journals (Sweden)

R. J. Apsimon

2015-03-01

Full Text Available A high-resolution, low-latency beam position monitor (BPM system has been developed for use in particle accelerators and beam lines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK in Japan. It consists of three stripline BPMs instrumented with analogue signal-processing electronics and a custom digitizer for logging the data. The design of the analogue processor units is presented in detail, along with measurements of the system performance. The processor latency is 15.6±0.1  ns. A single-pass beam position resolution of 291±10  nm has been achieved, using a beam with a bunch charge of approximately 1 nC.

High-resolution electron-energy-loss spectroscopy studies of clean and hydrogen-covered tungsten (100) surfaces

International Nuclear Information System (INIS)

Woods, J.P.

1986-01-01

High-resolution (10-meV FWHM) low-energy (≤ 100eV) electrons are scattered from the tungsten (100) surface. Electron-energy-loss spectroscopy (EELS) selection rules are utilized to identify vibrational modes of the surface tungsten atoms. A 36-meV mode is measured on the c(2 X 2) thermally reconstructed surface and is modeled as an overtone of the 18-meV mode at M in the surface Brillouin zone. The superstructure of the reconstructed surface allows this mode to be observed in specular scattering. The surface tungsten atoms return to their bulk lateral positions with saturated hydrogen (β 1 phase) adsorption; and a 26-meV mode identified is due to the perpendicular vibration of the surface tungsten layers. The clean-room temperature surface does not display either low-energy vibrations and the surface is modeled as disordered. The three β 1 phase hydrogen vibrations are observed and a new vibration at 118 meV is identified. The 118-meV cross section displays characteristics of a parallel mode, but calculations show this assignment to be erroneous. There are two hydrogen atoms for each surface tungsten atom in the β 1 phase, and lattice-dynamical calculations show that the 118-meV mode is due to a hydrogen-zone edge vibration. The predicted breakdown of the parallel hydrogen vibration selection rule was not observed

Development of high-spatial resolution TV Thomson scattering system for JFT-2M

International Nuclear Information System (INIS)

Yamauchi, Toshihiko; Shiina, Tomio; Kozawa, Teruo; Ishige, Youichi.

1996-01-01

The JFT-2M TV Thomson scattering system (TVTS) with high spatial resolution was completed in the cooperation of the fusion research and development for the DOE-JAERI collaborative program, and has been operated for 3 years. The system is composed of six subsystems; vacuum components, optics, detector, control and data acquisition, software and laser subsystems. TVTS was totally tested in the JFT-2M tokamak and the electron temperature and density profiles are measured with good reproducibility, and the increase of electron temperature by increasing toroidal magnetic field is also measured with TVTS. (author)

Fall speed measurement and high-resolution multi-angle photography of hydrometeors in free fall

OpenAIRE

T. J. Garrett; C. Fallgatter; K. Shkurko; D. Howlett

2012-01-01

We describe here a new instrument for imaging hydrometeors in free fall. The Multi-Angle Snowflake Camera (MASC) captures high-resolution photographs of hydrometeors from three angles while simultaneously measuring their fall speed. Based on the stereoscopic photographs captured over the two months of continuous measurements obtained at a high altitude location within the Wasatch Front in Utah, we derive statistics for fall speed, hydrometeor size, shape, orientation and asp...

Attofarad resolution capacitance-voltage measurement of nanometer scale field effect transistors utilizing ambient noise

International Nuclear Information System (INIS)

Gokirmak, Ali; Inaltekin, Hazer; Tiwari, Sandip

2009-01-01

A high resolution capacitance-voltage (C-V) characterization technique, enabling direct measurement of electronic properties at the nanoscale in devices such as nanowire field effect transistors (FETs) through the use of random fluctuations, is described. The minimum noise level required for achieving sub-aF (10 -18 F) resolution, the leveraging of stochastic resonance, and the effect of higher levels of noise are illustrated through simulations. The non-linear ΔC gate-source/drain -V gate response of FETs is utilized to determine the inversion layer capacitance (C inv ) and carrier mobility. The technique is demonstrated by extracting the carrier concentration and effective electron mobility in a nanoscale Si FET with C inv = 60 aF.

Geometrically necessary dislocation densities in olivine obtained using high-angular resolution electron backscatter diffraction

Energy Technology Data Exchange (ETDEWEB)

Wallis, David, E-mail: davidwa@earth.ox.ac.uk [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3AN (United Kingdom); Hansen, Lars N. [Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, Oxfordshire, OX1 3AN (United Kingdom); Ben Britton, T. [Department of Materials, Imperial College London, Royal School of Mines, Exhibition Road, London SW7 2AZ (United Kingdom); Wilkinson, Angus J. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxfordshire, OX1 3PH (United Kingdom)

2016-09-15

Dislocations in geological minerals are fundamental to the creep processes that control large-scale geodynamic phenomena. However, techniques to quantify their densities, distributions, and types over critical subgrain to polycrystal length scales are limited. The recent advent of high-angular resolution electron backscatter diffraction (HR-EBSD), based on diffraction pattern cross-correlation, offers a powerful new approach that has been utilised to analyse dislocation densities in the materials sciences. In particular, HR-EBSD yields significantly better angular resolution (<0.01°) than conventional EBSD (~0.5°), allowing very low dislocation densities to be analysed. We develop the application of HR-EBSD to olivine, the dominant mineral in Earth's upper mantle by testing (1) different inversion methods for estimating geometrically necessary dislocation (GND) densities, (2) the sensitivity of the method under a range of data acquisition settings, and (3) the ability of the technique to resolve a variety of olivine dislocation structures. The relatively low crystal symmetry (orthorhombic) and few slip systems in olivine result in well constrained GND density estimates. The GND density noise floor is inversely proportional to map step size, such that datasets can be optimised for analysing either short wavelength, high density structures (e.g. subgrain boundaries) or long wavelength, low amplitude orientation gradients. Comparison to conventional images of decorated dislocations demonstrates that HR-EBSD can characterise the dislocation distribution and reveal additional structure not captured by the decoration technique. HR-EBSD therefore provides a highly effective method for analysing dislocations in olivine and determining their role in accommodating macroscopic deformation. - Highlights: • Lattice orientation gradients in olivine were measured using HR-EBSD. • The limited number of olivine slip systems enable simple least squares inversion for GND

A Computer Controlled Precision High Pressure Measuring System

Science.gov (United States)

Sadana, S.; Yadav, S.; Jha, N.; Gupta, V. K.; Agarwal, R.; Bandyopadhyay, A. K.; Saxena, T. K.

2011-01-01

A microcontroller (AT89C51) based electronics has been designed and developed for high precision calibrator based on Digiquartz pressure transducer (DQPT) for the measurement of high hydrostatic pressure up to 275 MPa. The input signal from DQPT is converted into a square wave form and multiplied through frequency multiplier circuit over 10 times to input frequency. This input frequency is multiplied by a factor of ten using phased lock loop. Octal buffer is used to store the calculated frequency, which in turn is fed to microcontroller AT89C51 interfaced with a liquid crystal display for the display of frequency as well as corresponding pressure in user friendly units. The electronics developed is interfaced with a computer using RS232 for automatic data acquisition, computation and storage. The data is acquired by programming in Visual Basic 6.0. This system is interfaced with the PC to make it a computer controlled system. The system is capable of measuring the frequency up to 4 MHz with a resolution of 0.01 Hz and the pressure up to 275 MPa with a resolution of 0.001 MPa within measurement uncertainty of 0.025%. The details on the hardware of the pressure measuring system, associated electronics, software and calibration are discussed in this paper.

Fabrication and measurement of gas electron multiplier

International Nuclear Information System (INIS)

Zhang Minglong; Xia Yiben; Wang Linjun; Gu Beibei; Wang Lin; Yang Ying

2005-01-01

Gas electron multiplier (GEM) with special performance has been widely used in the field of radiation detectors. In this work, GEM film was fabricated using a 50 μm -thick kapton film by the therma evaporation and laser masking drilling technique. GEM film has many uniformly arrayed holes with a diameter of 100 μm and a gap of 223 μm. It was then set up to a gas-flowing detector with an effective area of 3 x 3 cm 2 , 5.9 keV X-ray generated from a 55 Fe source was used to measure the pulse height distribution of GEM operating at various high voltage and gas proportion. The effect of high potential and gas proportion on the count rate and the energy resolution was discussed in detail. The results indicate that GEM has a very high ratio of signal to noise and better energy resolution of 18.2%. (authors)

Electron density interferometry measurement in laser-matter interaction

International Nuclear Information System (INIS)

Popovics-Chenais, C.

1981-05-01

This work is concerned with the laser-interferometry measurement of the electronic density in the corona and the conduction zone external part. Particularly, it is aimed at showing up density gradients and at their space-time localization. The first chapter recalls the density profile influence on the absorption principal mechanisms and the laser energy transport. In chapter two, the numerical and analytical hydrodynamic models describing the density profile are analysed. The influence on the density profile of the ponderomotive force associated to high oscillating electric fields is studied, together with the limited thermal conduction and suprathermal electron population. The mechanism action, in our measurement conditions, is numerically simulated. Calculations are made with experimental parameters. The measurement interaction conditions, together with the diagnostic method by high resolution laser interferometry are detailed. The results are analysed with the help of numerical simulation which is the experiment modeling. An overview of the mechanisms shown up by interferometric measurements and their correlation with other diagnostics is the conclusion of this work [fr

High-resolution electron microscope image analysis approach for superconductor YBa2Cu3O7-x

International Nuclear Information System (INIS)

Xu, J.; Lu, F.; Jia, C.; Hua, Z.

1991-01-01

In this paper, an HREM (High-resolution electron microscope) image analysis approach has been developed. The image filtering, segmentation and particles extraction based on gray-scale mathematical morphological operations, are performed on the original HREM image. The final image is a pseudocolor image, with the background removed, relatively uniform brightness, filtered slanting elongation, regular shape for every kind of particle, and particle boundaries that no longer touch each other so that the superconducting material structure can be shown clearly

High resolution electron microscope study of the omega transformation in Zr--Nb alloys

International Nuclear Information System (INIS)

Chang, A.L.J.; Sass, S.L.; Krakow, W.

1976-01-01

High resolution direct lattice imaging and dark field electron microscopy were used to examine the omega phase transformation in Zr--Nb alloys. Direct lattice imaging demonstrated the existence of subvariants within an omega variant. The existence of an ordered sequence of subvariants, which is the basic premise of recent diffuse intensity calculations which seek to explain diffuse diffraction observations in high Nb content alloys, could not be checked because of the small size of the omega regions. In the low Nb content alloys dark field electron microscopy was used to show that the ω phase consists of large domains (100 to 200 A dia) the interior of which contains features that are 3 to 6 A dia. As the Nb content is increased the omega domains decrease in size until only 3 to 5 A images are observed in alloys containing 15 wt. percent Nb or more. The isolated images are present over the range of composition from 8 to 30 wt. percent Nb. Time sequence dark field micrographs show that these small images change with time. The diffuse ω reflections are believed due in part to the existence of a (111) linear detect, consisting of groups of (111) rows of atoms which are displaced from bcc to ω positions for short periods of time

Highly effective portable beta spectrometer for precise depth selective electron Moessbauer spectroscopy

International Nuclear Information System (INIS)

Aldiyarov, N.U.; Kadyrzhanov, K.K.; Seytimbetov, A.M.; Zhdanov, V.S.

2007-01-01

Full text: More broad application of the nuclear-physical method of precise Depth Selective Electron Moessbauer Spectroscopy (DS EMS) is limited by insufficient accessibility of highly-effective beta spectrometers with acceptable resolution. It should be mentioned that the method DS EMS is realized at a combined installation that consists of a highly-effective beta spectrometer and a conventional portable nuclear gamma-resonance spectrometer. Yet few available beta spectrometers have sophisticated design and controlling; in most cases they are cumbersome. All the attempts to simplify beta spectrometers resulted in noticeable worsening of depth resolution for the DS EMS method making the measurements non precise. There is currently an obvious need in a highly-effective portable easily controlled beta spectrometer. While developing such portable beta spectrometer, it is more promising to use as basis a simpler spectrometer, which has ratio of sample size to spectrometer size of about five times. The paper presents an equal-arm version of a highly-effective portable beta spectrometer with transverse heterogeneous sector magnetic field that assures double focusing. The spectrometer is equipped with a large-area non-equipotential source (a sample under investigation) and a position-sensitive detector. This portable spectrometer meets all requirements for achievement of the DS EMS depth resolution close to the physical limit and demonstrates the following main characteristics: equilibrium orbit radius ρ 0 = 80 mm, instrumental energy resolution 0.6 % at solid angle 1 % of 4π steradian, area of non-equipotential source ∼ 80 mm 2 , registration by position-sensitive detector of ∼ 10 % of the energy interval. Highly-effective portable beta spectrometer assures obtaining Moessbauer data with depth resolution close to physical limit of the DS EMS method. So in measurements at conversion and Auger electrons with energies of about units of keV and above, the achieved

Measuring high-resolution sky luminance distributions with a CCD camera.

Science.gov (United States)

Tohsing, Korntip; Schrempf, Michael; Riechelmann, Stefan; Schilke, Holger; Seckmeyer, Gunther

2013-03-10

We describe how sky luminance can be derived from a newly developed hemispherical sky imager (HSI) system. The system contains a commercial compact charge coupled device (CCD) camera equipped with a fish-eye lens. The projection of the camera system has been found to be nearly equidistant. The luminance from the high dynamic range images has been calculated and then validated with luminance data measured by a CCD array spectroradiometer. The deviation between both datasets is less than 10% for cloudless and completely overcast skies, and differs by no more than 20% for all sky conditions. The global illuminance derived from the HSI pictures deviates by less than 5% and 20% under cloudless and cloudy skies for solar zenith angles less than 80°, respectively. This system is therefore capable of measuring sky luminance with the high spatial and temporal resolution of more than a million pixels and every 20 s respectively.

High Resolution Transmission Electron Microscope Observation of Zero-Strain Deformation Twinning Mechanisms in Ag

Science.gov (United States)

Liu, L.; Wang, J.; Gong, S. K.; Mao, S. X.

2011-04-01

We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.

Dark field electron holography for strain measurement

Energy Technology Data Exchange (ETDEWEB)

Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

2011-02-15

Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

High resolution electron microscopy study of as-prepared and annealed tungsten-carbon multilayers

International Nuclear Information System (INIS)

Nguyen, T.D.; Gronsky, R.; Kortright, J.B.

1988-12-01

A series of sputtered tungsten-carbon multilayer structures with periods ranging from 2 to 12 nm in the as-prepared state and after annealing at 500/degree/C for 4 hours has been studied with high resolution transmission electron microscopy. The evolution with annealing of the microstructure of these multilayers depends on their period. As-prepared structures appear predominantly amorphous from TEM imaging and diffraction. Annealing results in crystallization of the W-rich layers into WC in the larger period samples, and less complete or no crystallization in the smaller period samples. X-ray scattering reveals that annealing expands the period in a systematic way. The layers remain remarkably well-defined after annealing under these conditions. 12 refs., 4 figs., 1 tab

Topics in the measurement of electrons with the ATLAS detector at the LHC

CERN Document Server

Thioye, Moustapha

2008-01-01

Upon completion in 2008, the Large Hadron Collider (LHC) will accelerate and collide protons with a 14~TeV center-of-mass energy at a designed luminosity of $10^{34}\\rm {cm^{-2}s^{-1}}$. The LHC will also be able to accelerate and collide heavy ions (Pb-Pb) at a nucleon-nucleon center of mass of 5.5~TeV. It will be the most powerful instrument ever built to investigate particles properties. The ATLAS (A Toroidal LHC ApparatuS) experiment is one of five experiments at the LHC. ATLAS is a general-purpose detector designed for the discovery of new particles predicted by the Standard Model (i.e Higgs boson), and of signatures of physics beyond the Standard Model (i.e supersymmetry). These discoveries require a highly efficient detection and high-resolution measurement of leptons or photons in the final state. In ATLAS, the liquid Argon (LAr) calorimeters identify and measure electrons and photons with high resolution. This dissertation reports on a study of various topics relevant to the measurement of electrons ...

Electron-impact-induced K plus M shell ionization in solid targets of medium-Z elements studied by means of high-resolution x-ray spectroscopy

International Nuclear Information System (INIS)

Ludziejewski, T.; Rymuza, P.; Sujkowski, Z.; Borchert, G.; Dousse, J.; Rheme, C.; Polasik, M.

1996-01-01

The Kβ 2 x-ray spectra of zirconium, niobium, molybdenum, and palladium bombarded by 150 and 300 keV electrons were measured with a high-resolution transmission curved crystal spectrometer. Multiconfiguration Dirac-Fock calculations were used for the decomposition of the experimental spectra into the Kβ 2 M 0 (diagram) and Kβ 2 M 1 (satellite) components. The probabilities of energy dependent (direct Coulomb and two-step) processes were estimated from the differences in the satellite line yields for electrons and photons. The satellite yields are found to be considerably enhanced in comparison with those for the proton-induced ionization recently measured and analyzed in the same way [T. Ludziejewski et al., Phys. Rev. A 52, 2791 (1995)]. This result indicates the importance of multielectron effects in the K plus M shell ionization by energetic projectiles. copyright 1996 The American Physical Society

Picosecond resolution on relativistic heavy ions' time-of-flight measurement

International Nuclear Information System (INIS)

Ebran, A.; Taieb, J.; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

2013-01-01

We developed a time-of-flight measurement system for relativistic heavy ions with a requested resolution of 40 ps Full Width Half Maximum. Such a resolution is mandatory to assign the correct mass number to every fission fragment, identified using the Bρ-ToF-ΔE method with the recoil spectrometer designed for the SOFIA experiment—which hold very recently at GSI. To achieve such a performance, fast plastic scintillators read-out by dedicated photomultiplier tubes were chosen among other possible options. We have led several test-measurements from 2009 to 2011, in order to investigate: the effect of the addition of a quenching molecule in the scintillator's matrix, the influence of the detector's size and the impact of the photomultiplier tube. The contribution of the dedicated electronics is also characterized. Time-of-flight measurements were performed realized with electron pulses and relativistic heavy ions, respectively provided by the LASER driven electron–accelerator (ELSA) at CEA–DAM Ile-de-France and by the SIS18/FRS facility at GSI. The reported results exhibit a time resolution better than 20 ps Full Width Half Maximum reached with the last prototype at GSI with an Uranium beam. These results confirm that the SOFIA experiment should enable the measurement of the relativistic fission fragments' time-of-flight with the requested resolution

High resolution photofission measurements in 238U and 232Th. Final report

International Nuclear Information System (INIS)

Lancman, H.

1985-12-01

A novel technique for measuring the photofission cross section with very high photon energy resolution has been developed. The photons are obtained from selected resonances in the (p,γ) reaction on various light nuclei. The photon energy resolution approaches 200 eV in favorable cases. The photon energy spread at each (p,γ) resonance is approx.20 keV on the average. Measurements of the photo-fission cross sections of 232 Th and 238 U have been carried out in the energy range from 5.8 to 12 MeV. Intermediate structure has been found in both nuclei at excitation energies around 6 MeV. Various properties of this structure, such as average areas of resonances, their spacing, width, and the underlying bakground, as well as the experimental fission probability averaged over the intermediate structure have been found to agree with theoretical predictions based on a double-humped fission barrier. In the case of 232 Th, the feature of this barrier, a rather high first hump and a deep secondary well, are quite different from those predicted by current theoretial barrier calculations. 13 refs., 4 figs., 3 tabs

High resolution (transformers.

Science.gov (United States)

Garcia-Souto, Jose A; Lamela-Rivera, Horacio

2006-10-16

A novel fiber-optic interferometric sensor is presented for vibrations measurements and analysis. In this approach, it is shown applied to the vibrations of electrical structures within power transformers. A main feature of the sensor is that an unambiguous optical phase measurement is performed using the direct detection of the interferometer output, without external modulation, for a more compact and stable implementation. High resolution of the interferometric measurement is obtained with this technique (transformers are also highlighted.

Measurements of picosecond pulses of a high-current electron accelerator

International Nuclear Information System (INIS)

Zheltov, K.A.; Petrenko, A.N.; Turundaevskaya, I.G.; Shalimanov, V.F.

1997-01-01

The duration of a picosecond high-current accelerator electron beam pulse duration is measured and its shape is determined using a measuring line, comprising a Faraday cup, a radiofrequency cable of minor length and a wide-band SRG-7 oscillograph. The procedure of data reconstruction according to regularization method is applied to determine the actual shape of the pulse measured

Measurement of the central ion and electron temperature of tokamak plasmas from the x-ray line radiation of high-Z impurity ions

International Nuclear Information System (INIS)

Bitter, M.; von Goeler, S.; Goldman, M.; Hill, K.W.; Horton, R.; Roney, W.; Sauthoff, N.; Stodiek, W.

1982-04-01

This paper describes measurements of the central ion and electron temperature of tokamak plasmas from the observation of the 1s - 2p resonance lines, and the associated dielectronic (1s 2 nl - 1s2pnl, with n greater than or equal to 2) satellites, of helium-like iron (Fe XXV) and titanium (Ti XXI). The satellite to resonance line ratios are very sensitive to the electron temperature and are used as an electron temperature diagnostic. The ion temperature is deduced from the Doppler width of the 1s - 2p resonance lines. The measurements have been performed with high resolution Bragg crystal spectrometers on the PLT (Princeton Large Torus) and PDX (Poloidal Divertor Experiment) tokamaks. The details of the experimental arrangement and line evaluation are described, and the ion and electron temperature results are compared with those obtained from independent diagnostic techniques, such as the analysis of charge-exchange neutrals and measurements of the electron cyclotron radiation. The obtained experimental results permit a detailed comparison with theoretical predictions

Accurate Mass Measurements for Planetary Microlensing Events Using High Angular Resolution Observations

Directory of Open Access Journals (Sweden)

Jean-Philippe Beaulieu

2018-04-01

Full Text Available The microlensing technique is a unique method to hunt for cold planets over a range of mass and separation, orbiting all varieties of host stars in the disk of our galaxy. It provides precise mass-ratio and projected separations in units of the Einstein ring radius. In order to obtain the physical parameters (mass, distance, orbital separation of the system, it is necessary to combine the result of light curve modeling with lens mass-distance relations and/or perform a Bayesian analysis with a galactic model. A first mass-distance relation could be obtained from a constraint on the Einstein ring radius if the crossing time of the source over the caustic is measured. It could then be supplemented by secondary constraints such as parallax measurements, ideally by using coinciding ground and space-born observations. These are still subject to degeneracies, like the orbital motion of the lens. A third mass-distance relation can be obtained thanks to constraints on the lens luminosity using high angular resolution observations with 8 m class telescopes or the Hubble Space Telescope. The latter route, although quite inexpensive in telescope time is very effective. If we have to rely heavily on Bayesian analysis and limited constraints on mass-distance relations, the physical parameters are determined to 30–40% typically. In a handful of cases, ground-space parallax is a powerful route to get stronger constraint on masses. High angular resolution observations will be able to constrain the luminosity of the lenses in the majority of the cases, and in favorable circumstances it is possible to derive physical parameters to 10% or better. Moreover, these constraints will be obtained in most of the planets to be discovered by the Euclid and WFIRST satellites. We describe here the state-of-the-art approaches to measure lens masses and distances with an emphasis on high angular resolution observations. We will discuss the challenges, recent results and

ASIC for time-of-flight measurements with picosecond timing resolution

Energy Technology Data Exchange (ETDEWEB)

Stankova, Vera; Shen, Wei; Harion, Tobias [Kirchhoff-Institute for Physics, Heidelberg Univ. (Germany)

2015-07-01

The Positron Emission Tomography (PET) images are especially affected by a high level of noise. This noise affects the potential to detect and discriminate the tumor in relation to the background. Including Time-of-Flight information, with picosecond time resolution, within the conventional PET scanners will improve the signal-to-noise ratio (SNR) and in sequence the quality of the medical images. A mix-mode ASIC (STIC3) has been developed for high precision timing measurements with Silicon Photomultipliers (SiPM). The STiC3 is 64-channel chip, with fully differential analog front-end for crosstalk and electronic noise immunity. It integrates Time to Digital Converters (TDC) with time binning of 50.2 ps for time and energy measurements. Measurements of the of the analog front-end show a time jitter less than 20 ps and jitter of the TDC together with the digital part is around 37 ps. Further the timing of a channel has been tested by injecting a pulse into two channels and measuring the time difference of the recorded timestamps. A Coincidence Time Resolution (CTR) of 215 ps FWHM has been obtained with 3.1 x 3.1 x 15 mm{sup 2} LYSO:Ce scintillator crystals and Hamamatsu SiPM matric (S12643-050CN(x)). Characterization measurements with the chip and its performances are presented.

Electricity electron measurement

International Nuclear Information System (INIS)

Kim, Sang Jin; Sung, Rak Jin

1985-11-01

This book deals with measurement of electricity and electron. It is divided into fourteen chapters, which depicts basic of electricity measurement, unit and standard, important electron circuit for measurement, instrument of electricity, impedance measurement, power and power amount measurement, frequency and time measurement, waveform measurement, record instrument and direct viewing instrument, super high frequency measurement, digital measurement on analog-digital convert, magnetic measurement on classification by principle of measurement, measurement of electricity application with principle sensors and systematization of measurement.

One- and two-phonon mixed-symmetry states in 94Mo in high-resolution electron and proton scattering

International Nuclear Information System (INIS)

Fujita, H.; Botha, N.T.; Burda, O.; Carter, J.; Fearick, R.W.; Foertsch, S.V.; Fransen, C.; Kuhar, M.; Lenhardt, A.; Neumann-Cosel, P. von; Neveling, R.; Pietralla, N.; Ponomarev, V.Yu.; Richter, A.; Scholten, O.; Sideras-Haddad, E.; Smit, F.D.; Wambach, J.

2007-01-01

High-resolution inelastic electron scattering experiments at the S-DALINAC and proton scattering experiments at iThemba LABS permit a thorough test of the nature of proposed one- and two-phonon symmetric and mixed-symmetric 2 + states of the nucleus 94 Mo. The combined analysis reveals the one-phonon content of the mixed-symmetry state and its isovector character suggested by microscopic calculations. The purity of two-phonon 2 + states is extracted

Measurements of low density, high velocity flow by electron beam fluorescence technique

International Nuclear Information System (INIS)

Soga, Takeo; Takanishi, Masaya; Yasuhara, Michiru

1981-01-01

A low density chamber with an electron gun system was made for the measurements of low density, high velocity (high Mach number) flow. This apparatus is a continuous running facility. The number density and the rotational temperature in the underexpanding free jet of nitrogen were measured along the axis of the jet by the electron beam fluorescence technique. The measurements were carried out from the vicinity of the exit of the jet to far downstream of the first Mach disk. Rotational nonequilibrium phenomena were observed in the hypersonic flow field as well as in the shock wave (Mach disk). (author)

High resolution beam profiling of X-ray free electron laser radiation by polymer imprint development.

Science.gov (United States)

Rösner, Benedikt; Döring, Florian; Ribič, Primož R; Gauthier, David; Principi, Emiliano; Masciovecchio, Claudio; Zangrando, Marco; Vila-Comamala, Joan; De Ninno, Giovanni; David, Christian

2017-11-27

High resolution metrology of beam profiles is presently a major challenge at X-ray free electron lasers. We demonstrate a characterization method based on beam imprints in poly (methyl methacrylate). By immersing the imprints formed at 47.8 eV into organic solvents, the regions exposed to the beam are removed similar to resist development in grayscale lithography. This allows for extending the sensitivity of the method by more than an order of magnitude compared to the established analysis of imprints created solely by ablation. Applying the Beer-Lambert law for absorption, the intensity distribution in a micron-sized focus can be reconstructed from one single shot with a high dynamic range, exceeding 10 3 . The procedure described here allows for beam characterization at free electron lasers revealing even faint beam tails, which are not accessible when using ablation imprint methods. We demonstrate the greatly extended dynamic range on developed imprints taken in focus of conventional Fresnel zone plates and spiral zone plates producing beams with a topological charge.

High-resolution measurement of the 16O(γ,pn) reaction

International Nuclear Information System (INIS)

Isaksson, L.

1996-10-01

The 16 O(γ,pn) reaction has been measured with a resolution high enough to resolve individual low-lying states in the residual 14 N nucleus. Partial cross-sections, available to the acceptance of the detector system, have been extracted for the individual states, and compared to a recent calculation based on absorption on one-pion exchange currents and the Δ resonance current. The experiment was performed at the Maxlab accelerator laboratory in Lund, Sweden, using tagged photons at an energy of 67 - 76 MeV. The proton detector angular range was 60 - 100 deg and the corresponding for the neutron detector 81 - 103 deg. A missing energy resolution of 1.5 MeV was obtained. The relative population of the states in the residual 14 N nucleus indicates that the reaction takes place predominantly on proton-neutron pairs coupled to (J π ,T) = (1 + ,0). The cross-section for absorption on (0 + ,1) pairs is strongly suppressed. Furthermore, the relative population of the states indicates that both L=0 and L=2 pairs participate in the reaction. 45 refs

An angle encoder for super-high resolution and super-high accuracy using SelfA

International Nuclear Information System (INIS)

Watanabe, Tsukasa; Kon, Masahito; Nabeshima, Nobuo; Taniguchi, Kayoko

2014-01-01

Angular measurement technology at high resolution for applications such as in hard disk drive manufacturing machines, precision measurement equipment and aspherical process machines requires a rotary encoder with high accuracy, high resolution and high response speed. However, a rotary encoder has angular deviation factors during operation due to scale error or installation error. It has been assumed to be impossible to achieve accuracy below 0.1″ in angular measurement or control after the installation onto the rotating axis. Self-calibration (Lu and Trumper 2007 CIRP Ann. 56 499; Kim et al 2011 Proc. MacroScale; Probst 2008 Meas. Sci. Technol. 19 015101; Probst et al Meas. Sci. Technol. 9 1059; Tadashi and Makoto 1993 J. Robot. Mechatronics 5 448; Ralf et al 2006 Meas. Sci. Technol. 17 2811) and cross-calibration (Probst et al 1998 Meas. Sci. Technol. 9 1059; Just et al 2009 Precis. Eng. 33 530; Burnashev 2013 Quantum Electron. 43 130) technologies for a rotary encoder have been actively discussed on the basis of the principle of circular closure. This discussion prompted the development of rotary tables which achieve reliable and high accuracy angular verification. We apply these technologies for the development of a rotary encoder not only to meet the requirement of super-high accuracy but also to meet that of super-high resolution. This paper presents the development of an encoder with 2 21 = 2097 152 resolutions per rotation (360°), that is, corresponding to a 0.62″ signal period, achieved by the combination of a laser rotary encoder supplied by Magnescale Co., Ltd and a self-calibratable encoder (SelfA) supplied by The National Institute of Advanced Industrial Science and Technology (AIST). In addition, this paper introduces the development of a rotary encoder to guarantee ±0.03″ accuracy at any point of the interpolated signal, with respect to the encoder at the minimum resolution of 2 33 , that is, corresponding to a 0.0015″ signal period

High-resolution electron microscopic evidence for the filamentous structure of the cyst wall in Giardia muris and Giardia duodenalis.

Science.gov (United States)

Erlandsen, S L; Bemrick, W J; Pawley, J

1989-10-01

High-resolution morphological studies of the cyst wall of Giardia spp. were performed using low-voltage scanning electron microscopy (LVSEM) and transmission electron microscopy (TEM). The cyst wall was composed of membranous and filamentous layers. The membranous layer consisted of an inner and an outer cyst membrane separated by a thin layer of cytoplasm. The filamentous layer contained individual filaments that ranged from 7 to 20 nm in diameter when measured by LVSEM, formed a dense meshwork with branches or interconnections, and were occasionally arranged on the surface in whorled patterns. Cysts of Giardia muris from mice, Giardia duodenalis from dogs, pigs, voles, beavers, muskrats, and humans, and Giardia psittaci from a bird (parakeet), possessed an essentially identical wall composed of filaments. Inducement of excystation in viable Giardia cysts produced a dramatic increase in the interfilament spacing over an entire cyst, but none was observed in heat-killed or chemically fixed control cysts. These results demonstrated that the cyst wall of Giardia spp. was composed of a complex arrangement of filaments, presumably formed during the process of encystment.

In situ electrical probing and bias-mediated manipulation of dielectric nanotubes in a high-resolution transmission electron microscope

International Nuclear Information System (INIS)

Golberg, D.; Mitome, M.; Kurashima, K.; Zhi, C.Y.; Tang, C.C.; Bando, Y.; Lourie, O.

2006-01-01

Boron nitride nanotubes filled with magnesium oxides [MgO, MgO 2 ] and/or hydroxide [Mg(OH) 2 ] are electrically probed and delicately manipulated inside a 300 kV JEOL-3000F high-resolution transmission analytical electron microscope equipped with a side-entry 'Nanofactory Instruments' piezoholder. At a low bias the nanotubes demonstrate truly insulating behavior. At a high bias of ±30 V they show reversible breakdown current of several dozens of nA. Under 300 kV electron beam irradiation the nanotubes are positively charged that allows us to perform on-demand manipulation with them through tuning of polarity and/or value of a bias voltage on a gold counterelectrode from -140 to +140 V, owing to the prominent electrostatic nanotube-electrode interactions

Optimized high energy resolution in γ-ray spectroscopy with AGATA triple cluster detectors

Energy Technology Data Exchange (ETDEWEB)

Wiens, Andreas

2011-06-20

achieved for events of each hit-segment multiplicity. For γ-ray energies of 1.33 MeV, an improvement of 20% was achieved. The study of electron trapping using a new position-sensitive correction method for the energy measurement was completed. The correction of electron trapping resulted in an additional improvement of the full width at half maximum of the peaks of the γ-spectra. A total energy resolution of 2.01 keV at 1.33 MeV was achieved with a segmented, large volume germanium detector. The position-sensitive operation enabled calculating the Fano factor, which resulted in F = 0.095 ± 0.005. Eventually, a significant improvement of the energy resolution was achieved. Consequently, the novel segmented high-purity germanium AGATA detectors are operated at significantly improved conditions superior to the common Ge detectors in energy and position resolution. The essential improvement arises from the redundant energy measurement of independent core and segment electrodes and from the correction of the position-dependent trapping effects.

High spatial and spectral resolution measurements of Jupiter's auroral regions using Gemini-North-TEXES

Science.gov (United States)

Sinclair, J. A.; Orton, G. S.; Greathouse, T. K.; Lacy, J.; Giles, R.; Fletcher, L. N.; Vogt, M.; Irwin, P. G.

2017-12-01

Jupiter exhibits auroral emission at a multitude of wavelengths. Auroral emission at X-ray, ultraviolet and near-infrared wavelengths demonstrate the precipitation of ion and electrons in Jupiter's upper atmosphere, at altitudes exceeding 250 km above the 1-bar level. Enhanced mid-infrared emission of CH4, C2H2, C2H4 and further hydrocarbons is also observed coincident with Jupiter's auroral regions. Retrieval analyses of infrared spectra from IRTF-TEXES (Texas Echelon Cross Echelle Spectrograph on NASA's Infrared Telescope Facility) indicate strong heating at the 1-mbar level and evidence of ion-neutral chemistry, which enriches the abundances of unsaturated hydrocarbons (Sinclair et al., 2017b, doi:10.1002/2017GL073529, Sinclair et al., 2017c (under review)). The extent to which these phenomena in the stratosphere are correlated and coupled physically with the shorter-wavelength auroral emission originating from higher altitudes has been a challenge due to the limited spatial resolution available on the IRTF. Smaller-scale features observed in the near-infrared and ultraviolet emission, such as the main `oval', transient `swirls' and dusk-active regions within the main oval (e.g. Stallard et al., 2014, doi:10.1016/j/Icarus.2015.12.044, Nichols et al., 2017, doi: 10.1002/2017GL073029) are potentially being blurred in the mid-infrared by the diffraction-limited resolution (0.7") of IRTF's 3-metre primary aperture. However, on March 17-19th 2017, we obtained spectral measurements of H2 S(1), CH4, C2H2, C2H4 and C2H6 emission of Jupiter's high latitudes using TEXES on Gemini-North, which has a 8-metre primary aperture. This rare opportunity combines the superior spectral resolving power of TEXES and the high spatial resolution provided by Gemini-North's 8-metre aperture. We will perform a retrieval analyses to determine the 3D distributions of temperature, C2H2, C2H4 and C2H6. The morphology will be compared with near-contemporaneous measurements of H3+ emission from

Development of high time-resolution laser flash equipment for thermal diffusivity measurements using miniature-size specimens

International Nuclear Information System (INIS)

Shikama, Tatsuo; Namba, Chusei; Kosuda, Michinori; Maeda, Yukio.

1994-01-01

For measurements of thermal diffusivity of miniature-size specimens heavily irradiated by neutrons, a new Q-switched laser-flash instrument was developed. In the present instrument the time-resolution was improved to 0.1 ms by using a laser-pulse width of 25 ns. The realization of high time-resolution made it possible to measure the thermal diffusivity of thin specimens. It is expected that copper of 0.7 mm thick, and SUS 304 of 0.1 mm could be used for the measurements. In case of ATJ graphite, 0.5 mm thick specimen could be used for the reliable measurement in the temperature range of 300-1300 K. (author)

Diagnostic for a high-repetition rate electron photo-gun and first measurements

Science.gov (United States)

Filippetto, D.; Doolittle, L.; Huang, G.; Norum, E.; Portmann, G.; Qian, H.; Sannibale, F.

2015-05-01

The APEX electron source at LBNL combines the high-repetition-rate with the high beam brightness typical of photoguns, delivering low emittance electron pulses at MHz frequency. Proving the high beam quality of the beam is an essential step for the success of the experiment, opening the doors of the high average power to brightness-hungry applications as X-Ray FELs, MHz ultrafast electron diffraction etc.. As first step, a complete characterization of the beam parameters is foreseen at the Gun beam energy of 750 keV. Diagnostics for low and high current measurements have been installed and tested, and measurements of cathode lifetime and thermal emittance in a RF environment with mA current performed. The recent installation of a double slit system, a deflecting cavity and a high precision spectrometer, allow the exploration of the full 6D phase space. Here we discuss the present layout of the machine and future upgrades, showing the latest results at low and high repetition rate, together with the tools and techniques used.

Ultra-precise measurement of optical aberrations for sub-Aangstroem transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Barthel, J.

2008-06-15

Quantitative investigations of material structures on an atomic scale by means of highresolution transmission electron microscopy (HRTEM) impose not only extreme demands on the mechanic and electromagnetic stability of the applied instruments but require also their precise electron-optical adjustment. Today a physical resolution well below one Aangstroem can be achieved with commercially available microscopes on a daily basis. However, the achieved resolution can often not be reliably exploited for the interpretation of the resulting microscopical data due to the presence of so-called higher-order lens aberrations. At the starting time of this work, a sufficiently accurate procedure to measure higher-order aberrations was urgently missing. Since aberration measurement is a mandatory prerequisite for any technique of aberration control enabling quantitative high-resolution microscopy, the goal of this work is to develop such a measurement procedure for the Sub-Aangstroem regime. The measurement procedures developed in the course of this work are based on the numerical evaluation of a series of images taken from an amorphous object under electron-beam illumination with varying tilt. New techniques have been developed for the evaluation of single images as well as for the optimised evaluation of the whole series. These procedures allow microscope users to perform quantitative HRTEM even at a resolution of 0.5 Aangstroem. The precision reached with the newly developed measurement procedures is unprecedented and surpasses existing solutions by at least one order of magnitude in any respect. All the concepts and procedures for aberration measurement developed in this work have been implemented in a software package which satisfies professional demands with respect to robustness, precision, speed and user-friendliness. The new automatic aberrationmeasurement procedures are suitable to establish HRTEM as a quantitative technique for material science investigations in the

Ultra-precise measurement of optical aberrations for sub-Aangstroem transmission electron microscopy

International Nuclear Information System (INIS)

Barthel, J.

2008-06-01

Quantitative investigations of material structures on an atomic scale by means of highresolution transmission electron microscopy (HRTEM) impose not only extreme demands on the mechanic and electromagnetic stability of the applied instruments but require also their precise electron-optical adjustment. Today a physical resolution well below one Aangstroem can be achieved with commercially available microscopes on a daily basis. However, the achieved resolution can often not be reliably exploited for the interpretation of the resulting microscopical data due to the presence of so-called higher-order lens aberrations. At the starting time of this work, a sufficiently accurate procedure to measure higher-order aberrations was urgently missing. Since aberration measurement is a mandatory prerequisite for any technique of aberration control enabling quantitative high-resolution microscopy, the goal of this work is to develop such a measurement procedure for the Sub-Aangstroem regime. The measurement procedures developed in the course of this work are based on the numerical evaluation of a series of images taken from an amorphous object under electron-beam illumination with varying tilt. New techniques have been developed for the evaluation of single images as well as for the optimised evaluation of the whole series. These procedures allow microscope users to perform quantitative HRTEM even at a resolution of 0.5 Aangstroem. The precision reached with the newly developed measurement procedures is unprecedented and surpasses existing solutions by at least one order of magnitude in any respect. All the concepts and procedures for aberration measurement developed in this work have been implemented in a software package which satisfies professional demands with respect to robustness, precision, speed and user-friendliness. The new automatic aberrationmeasurement procedures are suitable to establish HRTEM as a quantitative technique for material science investigations in the

Frontend electronics for high-precision single photo-electron timing using FPGA-TDCs

Energy Technology Data Exchange (ETDEWEB)

Cardinali, M., E-mail: cardinal@kph.uni-mainz.de [Institut für Kernphysik, Johannes Gutenberg-University Mainz, Mainz (Germany); Helmholtz Institut Mainz, Mainz (Germany); Dzyhgadlo, R.; Gerhardt, A.; Götzen, K.; Hohler, R.; Kalicy, G.; Kumawat, H.; Lehmann, D.; Lewandowski, B.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Ugur, C.; Zühlsdorf, M. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt (Germany); Dodokhov, V.Kh. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Britting, A. [Friedrich Alexander-University of Erlangen-Nuremberg, Erlangen (Germany); and others

2014-12-01

The next generation of high-luminosity experiments requires excellent particle identification detectors which calls for Imaging Cherenkov counters with fast electronics to cope with the expected hit rates. A Barrel DIRC will be used in the central region of the Target Spectrometer of the planned PANDA experiment at FAIR. A single photo-electron timing resolution of better than 100 ps is required by the Barrel DIRC to disentangle the complicated patterns created on the image plane. R and D studies have been performed to provide a design based on the TRB3 readout using FPGA-TDCs with a precision better than 20 ps RMS and custom frontend electronics with high-bandwidth pre-amplifiers and fast discriminators. The discriminators also provide time-over-threshold information thus enabling walk corrections to improve the timing resolution. Two types of frontend electronics cards optimised for reading out 64-channel PHOTONIS Planacon MCP-PMTs were tested: one based on the NINO ASIC and the other, called PADIWA, on FPGA discriminators. Promising results were obtained in a full characterisation using a fast laser setup and in a test experiment at MAMI, Mainz, with a small scale DIRC prototype. - Highlights: • Frontend electronics for Cherenkov detectors have been developed. • FPGA-TDCs have been used for high precision timing. • Time over threshold has been utilised for walk correction. • Single photo-electron timing resolution less than 100 ps has been achieved.

On the resolution of the electron microscopic radioautography

International Nuclear Information System (INIS)

Uchida, Kazuko; Daimon, Tateo; Kawai, Kazuhiro

1981-01-01

The aim of electron microscopic radioautography is to reveal the exact localization of certain substances at the macromolecular level. In order to attain this object the establishment of a fine grain development method is indispensable. Some of latent images are formed at the contact surface between the polyhedral halide silver grain and the section surface, where the impact of #betta# particles come directly from the section involved, and since it is in contact with the section it remains in place even after development and gelatin removal. This latent image finally becomes a developed silver grain in the electron microscope radioautogram. Although the limit of resolution in electron microscopic radioautography is supposed to be the diameter of halide silver grains in emulsion, it may be improved by considering the fact that the contact area between the halide silver grain and the section surface is the minimum unit of resolution. The minimum resolution of electron microscopic radioautography was determined histologically to be about 100A. (author)

Near-optimum procedure for half-life measurement by high-resolution gamma-ray spectrometry

International Nuclear Information System (INIS)

Parker, J.L.

1989-01-01

A near-optimum procedure for using high-resolution γ-ray spectrometry to measure the half-lives of appropriate γ-ray- emitting-nuclides is presented. Among the important points of the procedure are the employment of the reference source method for implicit correction of pileup and deadtime losses; the use of full-energy peak-area ratios as the fundamental measured quantities; and continuous, high-rate data acquisition to obtain good results in a fraction of a half-life if desired. Equations are given for estimating the precision of the computed half-lives in terms of total measurement time, number of spectral acquisitions, and the precision of peak-area ratios. Results of 169 Yb half-life measurements are given as an example of the procedure's application. 3 refs., 2 tabs

High resolution photoelectron spectroscopy

International Nuclear Information System (INIS)

Arko, A.J.

1988-01-01

Photoelectron Spectroscopy (PES) covers a very broad range of measurements, disciplines, and interests. As the next generation light source, the FEL will result in improvements over the undulator that are larger than the undulater improvements over bending magnets. The combination of high flux and high inherent resolution will result in several orders of magnitude gain in signal to noise over measurements using synchrotron-based undulators. The latter still require monochromators. Their resolution is invariably strongly energy-dependent so that in the regions of interest for many experiments (h upsilon > 100 eV) they will not have a resolving power much over 1000. In order to study some of the interesting phenomena in actinides (heavy fermions e.g.) one would need resolving powers of 10 4 to 10 5 . These values are only reachable with the FEL

High energy resolution measurement of the sup 238 U neutron capture yield from 1 to 100 keV

Energy Technology Data Exchange (ETDEWEB)

Macklin, R.L. (Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering); Perez, R.B. (Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering Oak Ridge National Lab., TN (United States)); De Saussure, G.; Ingle, R.W. (Oak Ridge National Lab., TN (United States))

1991-01-01

The purpose of this work is the precise determination of the {sup 238}U neutron capture yield (i.e. the probability of neutron capture) as a function of neutron energy with the highest available neutron energy resolution. The motivation for this undertaking arises from the central role played by the {sup 238}U neutron capture process in the neutron balance of both thermal reactors and fast breeder reactors. The present measurement was performed using the Oak Ridge Electron Linear Accelerator (ORELA) facility. The pulsed beam of neutrons from the ORELA facility is collimated on a sample of {sup 238}U. The neutron capture rate in the sample is measured, as a function of neutron time-of-flight (TOF) by detecting the {gamma}-rays from the {sup 238}U(n, {gamma}){sup 239}U reaction with a large {gamma}-ray detector surrounding the {sup 238}U sample. At each energy, the capture yield is proportional to the observed capture rate divided by the measured intensity of the neutron beam. The constant of proportionality (the normalization constant) is obtained from the ratio of theoretical to experimentally measured areas under small {sup 238}U resonances where the resonance parameters have been determined from high-resolution {sup 238}U transmission measurements. The cross section for the reaction {sup 238}U(n,{gamma}){sup 239}U can be derived from the measured capture yield if one applies appropriate corrections for multiple scattering and resonance self-shielding. Some 200 {sup 238}U neutron resonances in the energy range from 250 eV to 10 keV have been observed which had not been detected in previous measurements. (author).

High-Resolution Sonars: What Resolution Do We Need for Target Recognition?

Directory of Open Access Journals (Sweden)

Pailhas Yan

2010-01-01

Full Text Available Target recognition in sonar imagery has long been an active research area in the maritime domain, especially in the mine-counter measure context. Recently it has received even more attention as new sensors with increased resolution have been developed; new threats to critical maritime assets and a new paradigm for target recognition based on autonomous platforms have emerged. With the recent introduction of Synthetic Aperture Sonar systems and high-frequency sonars, sonar resolution has dramatically increased and noise levels decreased. Sonar images are distance images but at high resolution they tend to appear visually as optical images. Traditionally algorithms have been developed specifically for imaging sonars because of their limited resolution and high noise levels. With high-resolution sonars, algorithms developed in the image processing field for natural images become applicable. However, the lack of large datasets has hampered the development of such algorithms. Here we present a fast and realistic sonar simulator enabling development and evaluation of such algorithms.We develop a classifier and then analyse its performances using our simulated synthetic sonar images. Finally, we discuss sensor resolution requirements to achieve effective classification of various targets and demonstrate that with high resolution sonars target highlight analysis is the key for target recognition.

Energetics of small scale turbulence in the lower stratosphere from high resolution radar measurements

Directory of Open Access Journals (Sweden)

J. Dole

2001-08-01

Full Text Available Very high resolution radar measurements were performed in the troposphere and lower stratosphere by means of the PROUST radar. The PROUST radar operates in the UHF band (961 MHz and is located in St. Santin, France (44°39’ N, 2°12’ E. A field campaign involving high resolution balloon measurements and the PROUST radar was conducted during April 1998. Under the classical hypothesis that refractive index inhomogeneities at half radar wavelength lie within the inertial subrange, assumed to be isotropic, kinetic energy and temperature variance dissipation rates were estimated independently in the lower stratosphere. The dissipation rate of temperature variance is proportional to the dissipation rate of available potential energy. We therefore estimate the ratio of dissipation rates of potential to kinetic energy. This ratio is a key parameter of atmospheric turbulence which, in locally homogeneous and stationary conditions, is simply related to the flux Richardson number, Rf .Key words. Meteorology and atmospheric dynamics (turbulence – Radio science (remote sensing

Annular dark field electron microscope images with better than 2 A resolution at 100 kV

International Nuclear Information System (INIS)

Shin, D.H.; Kirkland, E.J.; Silcox, J.

1989-01-01

High-resolution scanning transmission electron microscope (STEM) images in the annular dark field (ADF) imaging mode approaching the theoretical point-to-point resolution limit are presented. The ADF images were obtained from a high T c superconducting YBa 2 Cu 3 O 7-x thin-film specimen at 100 kV. The 1.9 A resolution lattice image, which is the smallest lattice spacing in the specimen, corresponds to the minimum resolvable spatial frequency with 5% contrast in the contrast transfer function for annular dark field, and is smaller than the resolution limit given by the Rayleigh criterion. This demonstrates that STEM ADF imaging can have a resolution approximately 40% better than that of the bright field conventional transmission electron microscope (CTEM) imaging at Scherzer condition

Picosecond resolution on relativistic heavy ions' time-of-flight measurement

Energy Technology Data Exchange (ETDEWEB)

Ebran, A., E-mail: adeline.ebran@cea.fr; Taieb, J., E-mail: julien.taieb@cea.fr; Belier, G.; Chatillon, A.; Laurent, B.; Martin, J.-F.; Pellereau, E.

2013-11-11

We developed a time-of-flight measurement system for relativistic heavy ions with a requested resolution of 40 ps Full Width Half Maximum. Such a resolution is mandatory to assign the correct mass number to every fission fragment, identified using the Bρ-ToF-ΔE method with the recoil spectrometer designed for the SOFIA experiment—which hold very recently at GSI. To achieve such a performance, fast plastic scintillators read-out by dedicated photomultiplier tubes were chosen among other possible options. We have led several test-measurements from 2009 to 2011, in order to investigate: the effect of the addition of a quenching molecule in the scintillator's matrix, the influence of the detector's size and the impact of the photomultiplier tube. The contribution of the dedicated electronics is also characterized. Time-of-flight measurements were performed realized with electron pulses and relativistic heavy ions, respectively provided by the LASER driven electron–accelerator (ELSA) at CEA–DAM Ile-de-France and by the SIS18/FRS facility at GSI. The reported results exhibit a time resolution better than 20 ps Full Width Half Maximum reached with the last prototype at GSI with an Uranium beam. These results confirm that the SOFIA experiment should enable the measurement of the relativistic fission fragments' time-of-flight with the requested resolution.

HIGH-TIME-RESOLUTION MEASUREMENTS OF THE POLARIZATION OF THE CRAB PULSAR AT 1.38 GHz

Energy Technology Data Exchange (ETDEWEB)

Słowikowska, Agnieszka [Kepler Institute of Astronomy, University of Zielona Góra, Lubuska 2, 65-265 Zielona Góra (Poland); Stappers, Benjamin W. [Jodrell Bank Centre for Astrophysics, University of Manchester, Manchester M13 9PL (United Kingdom); Harding, Alice K. [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); O' Dell, Stephen L.; Elsner, Ronald F.; Weisskopf, Martin C. [Astrophysics Office, NASA Marshall Space Flight Center, ZP12, Huntsville, AL 35812 (United States); Van der Horst, Alexander J. [Astronomical Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam (Netherlands)

2015-01-20

Using the Westerbork Synthesis Radio Telescope, we obtained high-time-resolution measurements of the full polarization of the Crab pulsar. At a resolution of 1/8192 of the 34 ms pulse period (i.e., 4.1 μs), the 1.38 GHz linear-polarization measurements are in general agreement with previous lower-time-resolution 1.4 GHz measurements of linear polarization in the main pulse (MP), in the interpulse (IP), and in the low-frequency component (LFC). We find the MP and IP to be linearly polarized at about 24% and 21% with no discernible difference in polarization position angle. However, contrary to theoretical expectations and measurements in the visible, we find no evidence for significant variation (sweep) in the polarization position angle over the MP, the IP, or the LFC. We discuss the implications, which appear to be in contradiction to theoretical expectations. We also detect weak circular polarization in the MP and IP, and strong (≈20%) circular polarization in the LFC, which also exhibits very strong (≈98%) linear polarization at a position angle of 40° from that of the MP or IP. The properties are consistent with the LFC, which is a low-altitude component, and the MP and IP, which are high-altitude caustic components. Current models for the MP and IP emission do not readily account for the absence of pronounced polarization changes across the pulse. We measure IP and LFC pulse phases relative to the MP consistent with recent measurements, which have shown that the phases of these pulse components are evolving with time.

High-resolution transmission electron microscopy of grain-refining particles in amorphous aluminum alloys

International Nuclear Information System (INIS)

Schumacher, P.; Greer, A.L.

1996-01-01

The nucleation mechanism of Al-Ti-B grain refiners is studied in an Al-based amorphous alloy. The ability to limit growth of α-Al in the amorphous alloy permits the microscopical observation of nucleation events on boride particles. Earlier studies of this kind are extended by using high-resolution electron microscopy. This shows that the efficient nucleation α-Al depends on the TiB 2 particles being coated with a thin layer of Al 3 Ti, which can form only when there is some excess titanium in the melt. The aluminide layer, stabilized by adsorption effects, can be as little as a few monolayers thick, and is coherent with the boride. The nature of this layer, and its importance for the nucleation mechanism are discussed. The fading of the grain refinement action is also considered

Ultra-high resolution optical coherence tomography for encapsulation quality inspection

KAUST Repository

Czajkowski, Jakub

2011-08-28

We present the application of ultra-high resolution optical coherence tomography (UHR-OCT) in evaluation of thin, protective films used in printed electronics. Two types of sample were investigated: microscopy glass and organic field effect transistor (OFET) structure. Samples were coated with thin (1-3 μm) layer of parylene C polymer. Measurements were done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti: sapphire femtosecond laser, photonic crystal fibre and modified, free-space Michelson interferometer. Submicron resolution offered by the UHR-OCT system applied in the study enables registration of both interfaces of the thin encapsulation layer. Complete, volumetric characterisation of protective layers is presented, demonstrating possibility to use OCT for encapsulation quality inspection. © Springer-Verlag 2011.

Composition measurement in substitutionally disordered materials by atomic resolution energy dispersive X-ray spectroscopy in scanning transmission electron microscopy.

Science.gov (United States)

Chen, Z; Taplin, D J; Weyland, M; Allen, L J; Findlay, S D

2017-05-01

The increasing use of energy dispersive X-ray spectroscopy in atomic resolution scanning transmission electron microscopy invites the question of whether its success in precision composition determination at lower magnifications can be replicated in the atomic resolution regime. In this paper, we explore, through simulation, the prospects for composition measurement via the model system of Al x Ga 1-x As, discussing the approximations used in the modelling, the variability in the signal due to changes in configuration at constant composition, and the ability to distinguish between different compositions. Results are presented in such a way that the number of X-ray counts, and thus the expected variation due to counting statistics, can be gauged for a range of operating conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

Laboratory design for high-performance electron microscopy

Energy Technology Data Exchange (ETDEWEB)

O' Keefe, Michael A.; Turner, John H.; Hetherington, Crispin J.D.; Cullis, A.G.; Carragher, Bridget; Jenkins, Ron; Milgrim, Julie; Milligan,Ronald A.; Potter, Clinton S.; Allard, Lawrence F.; Blom, Douglas A.; Degenhardt, Lynn; Sides, William H.

2004-04-23

Proliferation of electron microscopes with field emission guns, imaging filters and hardware spherical aberration correctors (giving higher spatial and energy resolution) has resulted in the need to construct special laboratories. As resolutions improve, transmission electron microscopes (TEMs) and scanning transmission electron microscopes (STEMs) become more sensitive to ambient conditions. State-of-the-art electron microscopes require state-of-the-art environments, and this means careful design and implementation of microscope sites, from the microscope room to the building that surrounds it. Laboratories have been constructed to house high-sensitive instruments with resolutions ranging down to sub-Angstrom levels; we present the various design philosophies used for some of these laboratories and our experiences with them. Four facilities are described: the National Center for Electron Microscopy OAM Laboratory at LBNL; the FEGTEM Facility at the University of Sheffield; the Center for Integrative Molecular Biosciences at TSRI; and the Advanced Microscopy Laboratory at ORNL.

Development of the Atomic-Resolution Environmental Transmission Electron Microscope

DEFF Research Database (Denmark)

Gai, Pratibha L.; Boyes, Edward D.; Yoshida, Kenta

2016-01-01

The development of the novel atomic-resolution environmental transmission electron microscope (atomic-resolution ETEM) for directly probing dynamic gas–solid reactions in situ at the atomic level under controlled reaction conditions consisting of gas environment and elevated temperatures is descr......The development of the novel atomic-resolution environmental transmission electron microscope (atomic-resolution ETEM) for directly probing dynamic gas–solid reactions in situ at the atomic level under controlled reaction conditions consisting of gas environment and elevated temperatures...... is used to study steels, graphene, nanowires, etc. In this chapter, the experimental setup of the microscope column and its peripherals are described....

An improved image alignment procedure for high-resolution transmission electron microscopy.

Science.gov (United States)

Lin, Fang; Liu, Yan; Zhong, Xiaoyan; Chen, Jianghua

2010-06-01

Image alignment is essential for image processing methods such as through-focus exit-wavefunction reconstruction and image averaging in high-resolution transmission electron microscopy. Relative image displacements exist in any experimentally recorded image series due to the specimen drifts and image shifts, hence image alignment for correcting the image displacements has to be done prior to any further image processing. The image displacement between two successive images is determined by the correlation function of the two relatively shifted images. Here it is shown that more accurate image alignment can be achieved by using an appropriate aperture to filter the high-frequency components of the images being aligned, especially for a crystalline specimen with little non-periodic information. For the image series of crystalline specimens with little amorphous, the radius of the filter aperture should be as small as possible, so long as it covers the innermost lattice reflections. Testing with an experimental through-focus series of Si[110] images, the accuracies of image alignment with different correlation functions are compared with respect to the error functions in through-focus exit-wavefunction reconstruction based on the maximum-likelihood method. Testing with image averaging over noisy experimental images from graphene and carbon-nanotube samples, clear and sharp crystal lattice fringes are recovered after applying optimal image alignment. Copyright 2010 Elsevier Ltd. All rights reserved.

High resolution electron backscatter diffraction (EBSD) data from calcite biominerals in recent gastropod shells.

Science.gov (United States)

Pérez-Huerta, Alberto; Dauphin, Yannicke; Cuif, Jean Pierre; Cusack, Maggie

2011-04-01

Electron backscatter diffraction (EBSD) is a microscopy technique that reveals in situ crystallographic information. Currently, it is widely used for the characterization of geological materials and in studies of biomineralization. Here, we analyze high resolution EBSD data from biogenic calcite in two mollusk taxa, Concholepas and Haliotis, previously used in the understanding of complex biomineralization and paleoenvironmental studies. Results indicate that Concholepas has less ordered prisms than in Haliotis, and that in Concholepas the level of order is not homogenous in different areas of the shell. Overall, the usefulness of data integration obtained from diffraction intensity and crystallographic orientation maps, and corresponding pole figures, is discussed as well as its application to similar studies. © 2010 Elsevier Ltd. All rights reserved.

Confocal pore size measurement based on super-resolution image restoration.

Science.gov (United States)

Liu, Dali; Wang, Yun; Qiu, Lirong; Mao, Xinyue; Zhao, Weiqian

2014-09-01

A confocal pore size measurement based on super-resolution image restoration is proposed to obtain a fast and accurate measurement for submicrometer pore size of nuclear track-etched membranes (NTEMs). This method facilitates the online inspection of the pore size evolution during etching. Combining confocal microscopy with super-resolution image restoration significantly improves the lateral resolution of the NTEM image, yields a reasonable circle edge-setting criterion of 0.2408, and achieves precise pore edge detection. Theoretical analysis shows that the minimum measuring diameter can reach 0.19 μm, and the root mean square of the residuals is only 1.4 nm. Edge response simulation and experiment reveal that the edge response of the proposed method is better than 80 nm. The NTEM pore size measurement results obtained by the proposed method agree well with that obtained by scanning electron microscopy.

High-resolution spectroscopy of gases for industrial applications

DEFF Research Database (Denmark)

Fateev, Alexander; Clausen, Sønnik

High-resolution spectroscopy of gases is a powerful technique which has various fundamental and practical applications: in situ simultaneous measurements of gas temperature and gas composition, radiative transfer modeling, validation of existing and developing of new databases and etc. Existing...... databases (e.g. HITRAN, HITEMP or CDSD) can normally be used for absorption spectra calculations at limited temperature/pressure ranges. Therefore experimental measurements of absorption/transmission spectra gases (e.g. CO2, H2O or SO2) at high-resolution and elevated temperatures are essential both...... for analysis of complex experimental data and further development of the databases. High-temperature gas cell facilities available at DTU Chemical Engineering are presented and described. The gas cells and high-resolution spectrometers allow us to perform high-quality reference measurements of gases relevant...

Calibrating MMS Electron Drift Instrument (EDI) Ambient Electron Flux Measurements and Characterizing 3D Electric Field Signatures of Magnetic Reconnection

Science.gov (United States)

Shuster, J. R.; Torbert, R. B.; Vaith, H.; Argall, M. R.; Li, G.; Chen, L. J.; Ergun, R. E.; Lindqvist, P. A.; Marklund, G. T.; Khotyaintsev, Y. V.; Russell, C. T.; Magnes, W.; Le Contel, O.; Pollock, C. J.; Giles, B. L.

2015-12-01

The electron drift instruments (EDIs) onboard each MMS spacecraft are designed with large geometric factors (~0.01cm2 str) to facilitate detection of weak (~100 nA) electron beams fired and received by the two gun-detector units (GDUs) when EDI is in its "electric field mode" to determine the local electric and magnetic fields. A consequence of the large geometric factor is that "ambient mode" electron flux measurements (500 eV electrons having 0°, 90°, or 180° pitch angle) can vary depending on the orientation of the EDI instrument with respect to the magnetic field, a nonphysical effect that requires a correction. Here, we present determinations of the θ- and ø-dependent correction factors for the eight EDI GDUs, where θ (ø) is the polar (azimuthal) angle between the GDU symmetry axis and the local magnetic field direction, and compare the corrected fluxes with those measured by the fast plasma instrument (FPI). Using these corrected, high time resolution (~1,000 samples per second) ambient electron fluxes, combined with the unprecedentedly high resolution 3D electric field measurements taken by the spin-plane and axial double probes (SDP and ADP), we are equipped to accurately detect electron-scale current layers and electric field waves associated with the non-Maxwellian (anisotropic and agyrotropic) particle distribution functions predicted to exist in the reconnection diffusion region. We compare initial observations of the diffusion region with distributions and wave analysis from PIC simulations of asymmetric reconnection applicable for modeling reconnection at the Earth's magnetopause, where MMS will begin Science Phase 1 as of September 1, 2015.

Molecular imaging: High-resolution detectors for early diagnosis and therapy monitoring of breast cancer

Energy Technology Data Exchange (ETDEWEB)

Garibaldi, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy)]. E-mail: Franco.garibaldi@iss.infn.it; Cisbani, E. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Colilli, S. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Cusanno, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Fratoni, R. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Giuliani, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Gricia, M. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Lucentini, M. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Fratoni, R. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Lo Meo, S. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Magliozzi, M.L. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Santanvenere, F. [Istituto Superiore di Sanita and INFN-gr. Sanita-Rome (Italy); Cinti, M.N. [University La Sapienza, Rome (Italy); Pani, R. [University La Sapienza, Rome (Italy); Pellegrini, R. [University La Sapienza, Rome (Italy); Simonetti, G. [University Tor Vergata, Rome (Italy); Schillaci, O. [University Tor Vergata, Rome (Italy); Del Vecchio, S. [CNR Napoli, Naples (Italy); Salvatore, M. [CNR Napoli, Naples (Italy); Majewski, S. [Jefferson Lab, Newport News, VA (United States); Lanza, R.C. [Massachusetts Institute of Technology, Cambridge, MA (United States); De Vincentis, G. [University La Sapienza, Rome (Italy); Scopinaro, F. [University La Sapienza, Rome (Italy)

2006-12-20

Dedicated high-resolution detectors are required for detection of small cancerous breast tumours by molecular imaging with radionuclides. Absorptive collimation is normally applied in imaging single photon emitters, but it results in a strong reduction in detection efficiency. Systems based on electronic collimation are complex and expensive. For these reasons simulations and measurements have been performed to design optimised dedicated high-resolution mini gamma camera. Critical parameters are contrast and signal-to-noise ratio (SNR). Intrinsic performance (spatial resolution, pixel identification, and response linearity and uniformity) were first optimised. Pixellated scintillator arrays (NaI(Tl)) of different pixel size were coupled to arrays of PSPMTs with different anode pad dimensions (6x6 mm{sup 2} and 3x3 mm{sup 2}). Detectors having a field of view (FOV) of 100x100 mm{sup 2} and 150x200 mm{sup 2} were designed and built. The electronic system allows read out of all the anode pad signals. The collimation technique was then considered and limits of coded aperture option were studied. Preliminary results are presented.

High-resolution electron microscopy studies of the precipitation of copper under neutron irradiation in an Fe-1.3WT% Cu alloy

International Nuclear Information System (INIS)

Nicol, A. C.

1998-01-01

We have studied by electron microscopy the copper-rich precipitates in an Fe-1.3wt%Cu model alloy irradiated with neutrons to doses of 8.61 x 10 -3 dpa and 6.3 x 10 -2 dpa at a temperature of ∼270 C. In the lower dose material a majority (ca. 60%)of the precipitates visible in high-resolution electron microscopy were timed 9R precipitates of size ∼2-4 nm, while ca. 40% were untwinned. In the higher dose material, a majority (ca. 75%) of visible precipitates were untwinned although many still seemed to have a 9R structure. The average angle α between the herring-bone fringes in the twin variants was measured as 125 degree, not the 129 degree characteristic of precipitates in thermally-aged and electron-irradiated material immediately after the bcc->9R martensitic transformation. We argue that these results imply that the bcc->9R transformation of small (<4 nm) precipitates under neutron irradiation takes place at the irradiation temperature of 270 C rather than after subsequent cooling. Preliminary measurements showed that precipitate sizes did not depend strongly on dose, with a mean diameter of 3.4 ± 0.7 nm for the lower dose material, and 3.0 ± 0.5 nm for the higher dose material. This result agrees with the previous assumption that the lack of coarsening in precipitates formed under neutron irradiation is a consequence of the partial dissolution of larger precipitates by high-energy cascades

An (e, 2e + ion) study of low-energy electron-impact ionization and fragmentation of tetrahydrofuran with high mass and energy resolutions

Science.gov (United States)

Ren, Xueguang; Pflüger, Thomas; Weyland, Marvin; Baek, Woon Yoon; Rabus, Hans; Ullrich, Joachim; Dorn, Alexander

2014-10-01

We study the low-energy (E0 = 26 eV) electron-impact induced ionization and fragmentation of tetrahydrofuran using a reaction microscope. All three final-state charged particles, i.e., two outgoing electrons and one fragment ion, are detected in triple coincidence such that the momentum vectors and, consequently, the kinetic energies for charged reaction products are determined. The ionic fragments are clearly identified in the experiment with a mass resolution of 1 amu. The fragmentation pathways of tetrahydrofuran are investigated by measuring the ion kinetic energy spectra and the binding energy spectra where an energy resolution of 1.5 eV has been achieved using the recently developed photoemission electron source. Here, we will discuss the fragmentation reactions for the cations C4H8O+, C4H7O+, C2H3O+, C3H_6^+, C3H_5^+, C3H_3^+, CH3O+, CHO+, and C2H_3^+.

Potassium Stable Isotopic Compositions Measured by High-Resolution MC-ICP-MS

Science.gov (United States)

Morgan, Leah E.; Lloyd, Nicholas S.; Ellam, Robert M.; Simon, Justin I.

2012-01-01

Potassium isotopic (K-41/K-39) compositions are notoriously difficult to measure. TIMS measurements are hindered by variable fractionation patterns throughout individual runs and too few isotopes to apply an internal spike method for instrumental mass fractionation corrections. Internal fractionation corrections via the K-40/K-39 ratio can provide precise values but assume identical K-40/K-39 ratios (e.g. 0.05% (1sigma) in [1]); this is appropriate in some cases (e.g. identifying excess K-41) but not others (e.g., determining mass fractionation effects and metrologically traceable isotopic abundances). SIMS analyses have yielded measurements with 0.25% precisions (1sigma) [2]. ICP-MS analyses are significantly affected by interferences from molecular species such as Ar-38H(+) and Ar-40H(+) and instrument mass bias. Single collector ICP-MS instruments in "cold plasma" mode have yielded uncertainties as low as 2% (1sigma, e.g. [3]). Although these precisions may be acceptable for some concentration determinations, they do not resolve isotopic variation in terrestrial materials. Here we present data from a series of measurements made on the Thermo Scientific NEPTUNE Plus multi-collector ICP-MS that demonstrate the ability to make K-41/K-39 ratio measurements with 0.07% precisions (1sigma). These data, collected on NIST K standards, indicate the potential for MC-ICP-MS measurements to look for K isotopic variations at the sub-permil level. The NEPTUNE Plus can sufficiently resolve 39K and 41K from the interfering 38ArH+ and 40ArH+ peaks in wet cold plasma and high-resolution mode. Measurements were made on small but flat, interference-free, plateaus (ca. 50 ppm by mass width for K-41). Although ICP-MS does not yield accurate K-41/K-39 values due to significant instrumental mass fractionation (ca. 6%), this bias can be sufficiently stable over the time required for several measurements so that relative K-41/K-39 values can be precisely determined via sample

High-resolution electron microscopy of detonation nanodiamond

International Nuclear Information System (INIS)

Iakoubovskii, K; Mitsuishi, K; Furuya, K

2008-01-01

The structure of individual nanodiamond grains produced by the detonation of carbon-based explosives has been studied with a high-vacuum aberration-corrected electron microscope. Many grains show a well-resolved cubic diamond lattice with negligible contamination, thereby demonstrating that the non-diamond shell, universally observed on nanodiamond particles, could be intrinsic to the preparation process rather than to the nanosized diamond itself. The strength of the adhesion between the nanodiamond grains, and the possibility of their patterning with sub-nanometer precision, are also demonstrated

High-resolution electron microscopy of detonation nanodiamond

Energy Technology Data Exchange (ETDEWEB)

Iakoubovskii, K; Mitsuishi, K [Quantum Dot Research Center, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0005 (Japan); Furuya, K [High Voltage Microscopy Station, National Institute for Materials Science, 3-13 Sakura, Tsukuba 305-0005 (Japan)], E-mail: Iakoubovskii.Konstantin@nims.go.jp

2008-04-16

The structure of individual nanodiamond grains produced by the detonation of carbon-based explosives has been studied with a high-vacuum aberration-corrected electron microscope. Many grains show a well-resolved cubic diamond lattice with negligible contamination, thereby demonstrating that the non-diamond shell, universally observed on nanodiamond particles, could be intrinsic to the preparation process rather than to the nanosized diamond itself. The strength of the adhesion between the nanodiamond grains, and the possibility of their patterning with sub-nanometer precision, are also demonstrated.

Amorphous-like interfacial layer between a high-Tc superconducting Tl-1223 film and a Ag substrate examined by high-voltage high-resolution transmission electron microscopy

International Nuclear Information System (INIS)

Kim, Bongjun; Kim, Hyuntak; Nagai, Takuro; Matsui, Yoshio; Horiuchi, Shigeo; Jeong, Daeyeong; Deinhofer, Christian; Gritzner, Gerhard; Kim, Youngmin; Kim, Younjoong

2006-01-01

The thin amorphous-like layer, formed at the interface between a high-T c superconducting (Tl 0.5 , Pb 0.5 )(Sr 0.8 , Ba 0.2 )Ca 2 Cu 3 O y (Tl-1223) film and a Ag substrate during heating at 910 .deg. C, has been examined by using high-voltage high-resolution transmission electron microscopy. The interfacial layer is less than 10 nm in thickness. It contacts the (001) plane of Tl-1223 and the (113) or (133) planes of Ag in most cases. Its composition is similar to that of Tl-1223, except for the inclusion of a substantial amount of Ag. Its formation proceeds by diffusion of Ag into Tl-1223, during which a structure change first occurs at the layer of CuO 2 + Ca planes. The Tl(Pb)O + the Sr(Ba)O layers are then destroyed to cause the total structure to become amorphous-like. Furthermore, we have found that it is formed under an irradiation of highly energetic electrons.

Applications of high lateral and energy resolution imaging XPS with a double hemispherical analyser based spectromicroscope

International Nuclear Information System (INIS)

Escher, M.; Winkler, K.; Renault, O.; Barrett, N.

2010-01-01

The design and applications of an instrument for imaging X-ray photoelectron spectroscopy (XPS) are reviewed. The instrument is based on a photoelectron microscope and a double hemispherical analyser whose symmetric configuration avoids the spherical aberration (α 2 -term) inherent for standard analysers. The analyser allows high transmission imaging without sacrificing the lateral and energy resolution of the instrument. The importance of high transmission, especially for highest resolution imaging XPS with monochromated laboratory X-ray sources, is outlined and the close interrelation of energy resolution, lateral resolution and analyser transmission is illustrated. Chemical imaging applications using a monochromatic laboratory Al Kα-source are shown, with a lateral resolution of 610 nm. Examples of measurements made using synchrotron and laboratory ultra-violet light show the broad field of applications from imaging of core level electrons with chemical shift identification, high resolution threshold photoelectron emission microscopy (PEEM), work function imaging and band structure imaging.

A Simple Metric for Determining Resolution in Optical, Ion, and Electron Microscope Images.

Science.gov (United States)

Curtin, Alexandra E; Skinner, Ryan; Sanders, Aric W

2015-06-01

A resolution metric intended for resolution analysis of arbitrary spatially calibrated images is presented. By fitting a simple sigmoidal function to pixel intensities across slices of an image taken perpendicular to light-dark edges, the mean distance over which the light-dark transition occurs can be determined. A fixed multiple of this characteristic distance is then reported as the image resolution. The prefactor is determined by analysis of scanning transmission electron microscope high-angle annular dark field images of Si. This metric has been applied to optical, scanning electron microscope, and helium ion microscope images. This method provides quantitative feedback about image resolution, independent of the tool on which the data were collected. In addition, our analysis provides a nonarbitrary and self-consistent framework that any end user can utilize to evaluate the resolution of multiple microscopes from any vendor using the same metric.

High resolution Cerenkov light imaging of induced positron distribution in proton therapy

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Fujii, Kento; Morishita, Yuki; Okumura, Satoshi; Komori, Masataka [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673 (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Aichi 462-8508 (Japan)

2014-11-01

Purpose: In proton therapy, imaging of the positron distribution produced by fragmentation during or soon after proton irradiation is a useful method to monitor the proton range. Although positron emission tomography (PET) is typically used for this imaging, its spatial resolution is limited. Cerenkov light imaging is a new molecular imaging technology that detects the visible photons that are produced from high-speed electrons using a high sensitivity optical camera. Because its inherent spatial resolution is much higher than PET, the authors can measure more precise information of the proton-induced positron distribution with Cerenkov light imaging technology. For this purpose, they conducted Cerenkov light imaging of induced positron distribution in proton therapy. Methods: First, the authors evaluated the spatial resolution of our Cerenkov light imaging system with a {sup 22}Na point source for the actual imaging setup. Then the transparent acrylic phantoms (100 × 100 × 100 mm{sup 3}) were irradiated with two different proton energies using a spot scanning proton therapy system. Cerenkov light imaging of each phantom was conducted using a high sensitivity electron multiplied charge coupled device (EM-CCD) camera. Results: The Cerenkov light’s spatial resolution for the setup was 0.76 ± 0.6 mm FWHM. They obtained high resolution Cerenkov light images of the positron distributions in the phantoms for two different proton energies and made fused images of the reference images and the Cerenkov light images. The depths of the positron distribution in the phantoms from the Cerenkov light images were almost identical to the simulation results. The decay curves derived from the region-of-interests (ROIs) set on the Cerenkov light images revealed that Cerenkov light images can be used for estimating the half-life of the radionuclide components of positrons. Conclusions: High resolution Cerenkov light imaging of proton-induced positron distribution was possible. The

High resolution Cerenkov light imaging of induced positron distribution in proton therapy

International Nuclear Information System (INIS)

Yamamoto, Seiichi; Fujii, Kento; Morishita, Yuki; Okumura, Satoshi; Komori, Masataka; Toshito, Toshiyuki

2014-01-01

Purpose: In proton therapy, imaging of the positron distribution produced by fragmentation during or soon after proton irradiation is a useful method to monitor the proton range. Although positron emission tomography (PET) is typically used for this imaging, its spatial resolution is limited. Cerenkov light imaging is a new molecular imaging technology that detects the visible photons that are produced from high-speed electrons using a high sensitivity optical camera. Because its inherent spatial resolution is much higher than PET, the authors can measure more precise information of the proton-induced positron distribution with Cerenkov light imaging technology. For this purpose, they conducted Cerenkov light imaging of induced positron distribution in proton therapy. Methods: First, the authors evaluated the spatial resolution of our Cerenkov light imaging system with a 22 Na point source for the actual imaging setup. Then the transparent acrylic phantoms (100 × 100 × 100 mm 3 ) were irradiated with two different proton energies using a spot scanning proton therapy system. Cerenkov light imaging of each phantom was conducted using a high sensitivity electron multiplied charge coupled device (EM-CCD) camera. Results: The Cerenkov light’s spatial resolution for the setup was 0.76 ± 0.6 mm FWHM. They obtained high resolution Cerenkov light images of the positron distributions in the phantoms for two different proton energies and made fused images of the reference images and the Cerenkov light images. The depths of the positron distribution in the phantoms from the Cerenkov light images were almost identical to the simulation results. The decay curves derived from the region-of-interests (ROIs) set on the Cerenkov light images revealed that Cerenkov light images can be used for estimating the half-life of the radionuclide components of positrons. Conclusions: High resolution Cerenkov light imaging of proton-induced positron distribution was possible. The authors

Optimization of the ATLAS (s)MDT readout electronics for high counting rates

Energy Technology Data Exchange (ETDEWEB)

Kortner, Oliver; Kroha, Hubert; Nowak, Sebastian; Schmidt-Sommerfeld, Korbinian [Max-Planck-Institut fuer Physik (Werner-Heisenberg-Institut), Foehringer Ring 6, 80805 Muenchen (Germany)

2016-07-01

In the ATLAS muon spectrometer, Monitored Drift Tube (MDT) chambers are used for precise muon track measurement. For the high background rates expected at HL-LHC, which are mainly due to neutrons and photons produced by interactions of the proton collision products in the detector and shielding, new small-diameter muon drift tube (sMDT)-chambers with half the drift tube diameter of the MDT-chambers and ten times higher rate capability have been developed. The standard MDT readout electronics uses bipolar shaping in front of a discriminator. This shaping leads to an undershoot of same charge but opposite polarity following each pulse. With count rates also the probability of having the subsequent pulse in this undershoot increases, which leads to losses in efficiency and spatial resolution. In order to decrease this effect, discrete prototype electronics including Baseline Restoration has been developed. Results of their tests and data taken with them during muon beamtime measurements at CERN's Gamma Irradiation Facility will be presented. which causes a deterioration of signal pulses by preceding background hits, leading to losses in muon efficiency and drift tube spatial resolution. In order to mitigate these so-called signal pile-up effects, new readout electronics with active baseline restoration (BLR) is under development. Discrete prototype electronics with BLR functionality has been tested in laboratory measurements and in the Gamma Irradiation Facility at CERN under high γ-irradiation rates. Results of the measurements are presented.

The investigation of active Martian dune fields using very high resolution photogrammetric measurements

Science.gov (United States)

Kim, Jungrack; Kim, Younghwi; Park, Minseong

2016-10-01

At the present time, arguments continue regarding the migration speeds of Martian dune fields and their correlation with atmospheric circulation. However, precisely measuring the spatial translation of Martian dunes has succeeded only a very few times—for example, in the Nili Patera study (Bridges et al. 2012) using change-detection algorithms and orbital imagery. Therefore, in this study, we developed a generic procedure to precisely measure the migration of dune fields with recently introduced 25-cm resolution orbital imagery specifically using a high-accuracy photogrammetric processor. The processor was designed to trace estimated dune migration, albeit slight, over the Martian surface by 1) the introduction of very high resolution ortho images and stereo analysis based on hierarchical geodetic control for better initial point settings; 2) positioning error removal throughout the sensor model refinement with a non-rigorous bundle block adjustment, which makes possible the co-alignment of all images in a time series; and 3) improved sub-pixel co-registration algorithms using optical flow with a refinement stage conducted on a pyramidal grid processor and a blunder classifier. Moreover, volumetric changes of Martian dunes were additionally traced by means of stereo analysis and photoclinometry. The established algorithms have been tested using high-resolution HIRISE time-series images over several Martian dune fields. Dune migrations were iteratively processed both spatially and volumetrically, and the results were integrated to be compared to the Martian climate model. Migrations over well-known crater dune fields appeared to be almost static for the considerable temporal periods and were weakly correlated with wind directions estimated by the Mars Climate Database (Millour et al. 2015). As a result, a number of measurements over dune fields in the Mars Global Dune Database (Hayward et al. 2014) covering polar areas and mid-latitude will be demonstrated

A high-resolution photoelectron imaging and theoretical study of CP- and C2P.

Science.gov (United States)

Czekner, Joseph; Cheung, Ling Fung; Johnson, Eric L; Fortenberry, Ryan C; Wang, Lai-Sheng

2018-01-28

The discovery of interstellar anions has been a milestone in astrochemistry. In the search for new interstellar anions, CP - and C 2 P - are viable candidates since their corresponding neutrals have already been detected astronomically. However, scarce data exist for these negatively charged species. Here we report the electron affinities of CP and C 2 P along with the vibrational frequencies of their anions using high-resolution photoelectron imaging. These results along with previous spectroscopic data of the neutral species are used further to benchmark very accurate quartic force field quantum chemical methods that are applied to CP, CP - , C 2 P, and two electronic states of C 2 P - . The predicted electron affinities, vibrational frequencies, and rotational constants are in excellent agreement with the experimental data. The electron affinities of CP (2.8508 ± 0.0007 eV) and C 2 P (2.6328 ± 0.0006 eV) are measured accurately and found to be quite high, suggesting that the CP - and C 2 P - anions are thermodynamically stable and possibly observable. The current study suggests that the combination of high-resolution photoelectron imaging and quantum chemistry can be used to determine accurate molecular constants for exotic radical species of astronomical interest.

Progress in high-resolution x-ray holographic microscopy

International Nuclear Information System (INIS)

Jacobsen, C.; Kirz, J.; Howells, M.; McQuaid, K.; Rothman, S.; Feder, R.; Sayre, D.

1987-07-01

Among the various types of x-ray microscopes that have been demonstrated, the holographic microscope has had the largest gap between promise and performance. The difficulties of fabricating x-ray optical elements have led some to view holography as the most attractive method for obtaining the ultimate in high resolution x-ray micrographs; however, we know of no investigations prior to 1987 that clearly demonstrated submicron resolution in reconstructed images. Previous efforts suffered from problems such as limited resolution and dynamic range in the recording media, low coherent x-ray flux, and aberrations and diffraction limits in visible light reconstruction. We have addressed the recording limitations through the use of an undulator x-ray source and high-resolution photoresist recording media. For improved results in the readout and reconstruction steps, we have employed metal shadowing and transmission electron microscopy, along with numerical reconstruction techniques. We believe that this approach will allow holography to emerge as a practical method of high-resolution x-ray microscopy. 30 refs., 4 figs

Progress in high-resolution x-ray holographic microscopy

Energy Technology Data Exchange (ETDEWEB)

Jacobsen, C.; Kirz, J.; Howells, M.; McQuaid, K.; Rothman, S.; Feder, R.; Sayre, D.

1987-07-01

Among the various types of x-ray microscopes that have been demonstrated, the holographic microscope has had the largest gap between promise and performance. The difficulties of fabricating x-ray optical elements have led some to view holography as the most attractive method for obtaining the ultimate in high resolution x-ray micrographs; however, we know of no investigations prior to 1987 that clearly demonstrated submicron resolution in reconstructed images. Previous efforts suffered from problems such as limited resolution and dynamic range in the recording media, low coherent x-ray flux, and aberrations and diffraction limits in visible light reconstruction. We have addressed the recording limitations through the use of an undulator x-ray source and high-resolution photoresist recording media. For improved results in the readout and reconstruction steps, we have employed metal shadowing and transmission electron microscopy, along with numerical reconstruction techniques. We believe that this approach will allow holography to emerge as a practical method of high-resolution x-ray microscopy. 30 refs., 4 figs.

Photoionization study of doubly-excited helium at ultra-high resolution

Energy Technology Data Exchange (ETDEWEB)

Kaindl, G.; Schulz, K.; Domke, M. [Freie Universitaet Berlin (Germany)] [and others

1997-04-01

Ever since the pioneering work of Madden & Codling and Cooper, Fano & Prats on doubly-excited helium in the early sixties, this system may be considered as prototypical for the study of electron-electron correlations. More detailed insight into these states could be reached only much later, when improved theoretical calculations of the optically-excited {sup 1}P{sup 0} double-excitation states became available and sufficiently high energy resolution ({delta}E=4.0 meV) was achieved. This allowed a systematic investigation of the double-excitation resonances of He up to excitation energies close to the double-ionization threshold, I{sub infinity}=79.003 eV, which stimulated renewed theoretical interest into these correlated electron states. The authors report here on striking progress in energy resolution in this grazing-incidence photon-energy range of grating monochromators and its application to hitherto unobservable states of doubly-excited He. By monitoring an extremely narrow double-excitation resonance of He, with a theoretical lifetime width of less than or equal to 5 {mu}eV, a resolution of {delta}E=1.0 meV (FWHM) at 64.1 eV could be achieved. This ultra-high spectral resolution, combined with high photon flux, allowed the investigation of new Rydberg resonances below the N=3 ionization threshold, I{sub 3}, as well as a detailed comparison with ab-initio calculations.

Droplet deposition measurement with high-speed camera and novel high-speed liquid film sensor with high spatial resolution

International Nuclear Information System (INIS)

Damsohn, M.; Prasser, H.-M.

2011-01-01

Highlights: → Development of a sensor for time- and space-resolved droplet deposition in annular flow. → Experimental measurement of droplet deposition in horizontal annular flow to compare readings of the sensor with images of a high-speed camera when droplets are depositing unto the liquid film. → Self-adaptive signal filter based on autoregression to separate droplet impacts in the sensor signal from waves of liquid films. - Abstract: A sensor based on the electrical conductance method is presented for the measurement of dynamic liquid films in two-phase flow. The so called liquid film sensor consists of a matrix with 64 x 16 measuring points, a spatial resolution of 3.12 mm and a time resolution of 10 kHz. Experiments in a horizontal co-current air-water film flow were conducted to test the capability of the sensor to detect droplet deposition from the gas core onto the liquid film. The experimental setup is equipped with the liquid film sensor and a high speed camera (HSC) recording the droplet deposition with a sampling rate of 10 kHz simultaneously. In some experiments the recognition of droplet deposition on the sensor is enhanced by marking the droplets with higher electrical conductivity. The comparison between the HSC and the sensor shows, that the sensor captures the droplet deposition above a certain droplet diameter. The impacts of droplet deposition can be filtered from the wavy structures respectively conductivity changes of the liquid film using a filter algorithm based on autoregression. The results will be used to locally measure droplet deposition e.g. in the proximity of spacers in a subchannel geometry.

Global carbon monoxide vertical distributions from spaceborne high-resolution FTIR nadir measurements

Directory of Open Access Journals (Sweden)

B. Barret

2005-01-01

Full Text Available This paper presents the first global distributions of CO vertical profiles retrieved from a thermal infrared FTS working in the nadir geometry. It is based on the exploitation of the high resolution and high quality spectra measured by the Interferometric Monitor of Greenhouse gases (IMG which flew onboard the Japanese ADEOS platform in 1996-1997. The retrievals are performed with an algorithm based on the Optimal Estimation Method (OEM and are characterized in terms of vertical sensitivity and error budget. It is found that most of the IMG measurements contain between 1.5 and 2.2 independent pieces of information about the vertical distribution of CO from the lower troposphere to the upper troposphere-lower stratosphere (UTLS. The retrievals are validated against coincident NOAA/CMDL in situ surface measurements and NDSC/FTIR total columns measurements. The retrieved global distributions of CO are also found to be in good agreement with the distributions modeled by the GEOS-CHEM 3D CTM, highlighting the ability of IMG to capture the horizontal as well as the vertical structure of the CO distributions.

High current table-top setup for femtosecond gas electron diffraction

Directory of Open Access Journals (Sweden)

Omid Zandi

2017-07-01

Full Text Available We have constructed an experimental setup for gas phase electron diffraction with femtosecond resolution and a high average beam current. While gas electron diffraction has been successful at determining molecular structures, it has been a challenge to reach femtosecond resolution while maintaining sufficient beam current to retrieve structures with high spatial resolution. The main challenges are the Coulomb force that leads to broadening of the electron pulses and the temporal blurring that results from the velocity mismatch between the laser and electron pulses as they traverse the sample. We present here a device that uses pulse compression to overcome the Coulomb broadening and deliver femtosecond electron pulses on a gas target. The velocity mismatch can be compensated using laser pulses with a tilted intensity front to excite the sample. The temporal resolution of the setup was determined with a streak camera to be better than 400 fs for pulses with up to half a million electrons and a kinetic energy of 90 keV. The high charge per pulse, combined with a repetition rate of 5 kHz, results in an average beam current that is between one and two orders of magnitude higher than previously demonstrated.

In situ high-resolution transmission electron microscopy synthesis observation of nanostructured carbon coated LiFePO 4

Science.gov (United States)

Trudeau, M. L.; Laul, D.; Veillette, R.; Serventi, A. M.; Mauger, A.; Julien, C. M.; Zaghib, K.

In situ high-resolution transmission electron microscopy (HRTEM) studies of the structural transformations that occur during the synthesis of carbon-coated LiFePO 4 (C-LiFePO 4) and heat treatment to elevated temperatures were conducted in two different electron microscopes. Both microscopes have sample holders that are capable of heating up to 1500 °C, with one working under high vacuum and the other capable of operating with the sample surrounded by a low gaseous environment. The C-LiFePO 4 samples were prepared using three different compositions of precursor materials with Fe(0), Fe(II) or Fe(III), a Li-containing salt and a polyethylene- block-poly(ethylene glycol)-50% ethylene oxide or lactose. The in situ TEM studies suggest that low-cost Fe(0) and a low-cost carbon-containing compound such as lactose are very attractive precursors for mass production of C-LiFePO 4, and that 700 °C is the optimum synthesis temperature. At temperatures higher than 800 °C, LiFePO 4 has a tendency to decompose. The same in situ measurements have been made on particles without carbon coat. The results show that the homogeneous deposit of the carbon deposit at 700 °C is the result of the annealing that cures the disorder of the surface layer of bare LiFePO 4. Electrochemical tests supported the conclusion that the C-LiFePO 4 derived from Fe(0) is the most attractive for mass production.

High-performance electronics for time-of-flight PET systems

International Nuclear Information System (INIS)

Choong, W-S; Peng, Q; Vu, C Q; Turko, B T; Moses, W W

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr 3 crystals respectively.

Variations in energy, flux, and brightness of pulsating aurora measured at high time resolution

Directory of Open Access Journals (Sweden)

H. Dahlgren

2017-03-01

Full Text Available High-resolution multispectral optical and incoherent scatter radar data are used to study the variability of pulsating aurora. Two events have been analysed, and the data combined with electron transport and ion chemistry modelling provide estimates of the energy and energy flux during both the ON and OFF periods of the pulsations. Both the energy and energy flux are found to be reduced during each OFF period compared with the ON period, and the estimates indicate that it is the number flux of foremost higher-energy electrons that is reduced. The energies are found never to drop below a few kilo-electronvolts during the OFF periods for these events. The high-resolution optical data show the occurrence of dips in brightness below the diffuse background level immediately after the ON period has ended. Each dip lasts for about a second, with a reduction in brightness of up to 70 % before the intensity increases to a steady background level again. A different kind of variation is also detected in the OFF period emissions during the second event, where a slower decrease in the background diffuse emission is seen with its brightness minimum just before the ON period, for a series of pulsations. Since the dips in the emission level during OFF are dependent on the switching between ON and OFF, this could indicate a common mechanism for the precipitation during the ON and OFF phases. A statistical analysis of brightness rise, fall, and ON times for the pulsations is also performed. It is found that the pulsations are often asymmetric, with either a slower increase of brightness or a slower fall.

Imaging modes for potential mapping in semiconductor devices by electron holography with improved lateral resolution

Energy Technology Data Exchange (ETDEWEB)

Sickmann, Jan, E-mail: jan.sickmann@triebenberg.de [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany); Formanek, Petr; Linck, Martin [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany); Muehle, Uwe [Institut fuer Werkstoffwissenschaft, Technische Universitaet Bergakademie Freiberg, 09599 Freiberg (Germany); Lichte, Hannes [Triebenberg Laboratory, Institute of Structure Physics, Technische Universitaet Dresden, 01069 Dresden (Germany)

2011-03-15

Electron holography is the highest resolving tool for dopant profiling at nanometre-scale resolution. In order to measure the object areas of interest in a hologram, both a wide field of view and a sufficient lateral resolution are required. The usual path of rays for recording holograms with an electron biprism using the standard objective lens does not meet these requirements, because the field of view amounts to some 10 nm only, however, at a resolution of 0.1 nm better than needed here. Therefore, instead of the standard objective lens, the Lorentz lens is widely used for holography of semiconductors, since it provides a field of view up to 1000 nm at a sufficient lateral resolution of about 10 nm. Since the size of semiconductor structures is steadily shrinking, there is now a need for better lateral resolution at an appropriate field of view. Therefore, additional paths of rays for recording holograms are studied with special emphasis on the parameters field of view and lateral resolution. The findings allow an optimized scheme with a field of view of 200 nm and a lateral resolution of 3.3 nm filling the gap between the existing set-ups. In addition, the Lorentz lens is no longer required for investigation of non-magnetic materials, since the new paths of rays are realized with the standard objective lens and diffraction lens. An example proves the applicability of this arrangement for future semiconductor technology. -- Research highlights: {yields} Imaging modes for potential mapping in semiconductor devices by electron holography. {yields} Using objective and diffraction lens for imaging instead of Lorentz lens. {yields} Detailed investigation of four different paths of rays and its basic parameters for holographic application: field of view, lateral resolution, signal resolution. {yields} Measuring the phase profile of a field effect transistor with 3 nm lateral resolution at field of view of 200 nm.

Nano features of Al/Au ultrasonic bond interface observed by high resolution transmission electron microscopy

International Nuclear Information System (INIS)

Ji Hongjun; Li Mingyu; Kim, Jong-Myung; Kim, Dae-Won; Wang Chunqing

2008-01-01

Nano-scale interfacial details of ultrasonic AlSi1 wire wedge bonding to a Au/Ni/Cu pad were investigated using high resolution transmission electron microscopy (HRTEM). The intermetallic phase Au 8 Al 3 formed locally due to diffusion and reaction activated by ultrasound at the Al/Au bond interface. Multilayer sub-interfaces roughly parallel to the wire/pad interface were observed among this phase, and interdiffusional features near the Au pad resembled interference patterns, alternately dark and bright bars. Solid-state diffusion theory cannot be used to explain why such a thick compound formed within milliseconds at room temperature. The major formation of metallurgical bonds was attributed to ultrasonic cyclic vibration

Reconstruction of high temporal resolution Thomson scattering data during a modulated electron cyclotron resonance heating using conditional averaging

International Nuclear Information System (INIS)

Kobayashi, T.; Yoshinuma, M.; Ohdachi, S.; Ida, K.; Itoh, K.; Moon, C.; Yamada, I.; Funaba, H.; Yasuhara, R.; Tsuchiya, H.; Yoshimura, Y.; Igami, H.; Shimozuma, T.; Kubo, S.; Tsujimura, T. I.; Inagaki, S.

2016-01-01

This paper provides a software application of the sampling scope concept for fusion research. The time evolution of Thomson scattering data is reconstructed with a high temporal resolution during a modulated electron cyclotron resonance heating (MECH) phase. The amplitude profile and the delay time profile of the heat pulse propagation are obtained from the reconstructed signal for discharges having on-axis and off-axis MECH depositions. The results are found to be consistent with the MECH deposition.

Reconstruction of high temporal resolution Thomson scattering data during a modulated electron cyclotron resonance heating using conditional averaging

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, T., E-mail: kobayashi.tatsuya@LHD.nifs.ac.jp; Yoshinuma, M.; Ohdachi, S. [National Institute for Fusion Science, Toki 509-5292 (Japan); SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292 (Japan); Ida, K. [National Institute for Fusion Science, Toki 509-5292 (Japan); SOKENDAI (The Graduate University for Advanced Studies), Toki 509-5292 (Japan); Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Itoh, K. [National Institute for Fusion Science, Toki 509-5292 (Japan); Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Moon, C.; Yamada, I.; Funaba, H.; Yasuhara, R.; Tsuchiya, H.; Yoshimura, Y.; Igami, H.; Shimozuma, T.; Kubo, S.; Tsujimura, T. I. [National Institute for Fusion Science, Toki 509-5292 (Japan); Inagaki, S. [Research Center for Plasma Turbulence, Kyushu University, Kasuga 816-8580 (Japan); Research Institute for Applied Mechanics, Kyushu University, Kasuga 816-8580 (Japan)

2016-04-15

This paper provides a software application of the sampling scope concept for fusion research. The time evolution of Thomson scattering data is reconstructed with a high temporal resolution during a modulated electron cyclotron resonance heating (MECH) phase. The amplitude profile and the delay time profile of the heat pulse propagation are obtained from the reconstructed signal for discharges having on-axis and off-axis MECH depositions. The results are found to be consistent with the MECH deposition.

High Resolution Tracking Devices Based on Capillaries Filled with Liquid Scintillator

CERN Multimedia

Bonekamper, D; Vassiltchenko, V; Wolff, T

2002-01-01

%RD46 %title\\\\ \\\\The aim of the project is to develop high resolution tracking devices based on thin glass capillary arrays filled with liquid scintillator. This technique provides high hit densities and a position resolution better than 20 $\\mu$m. Further, their radiation hardness makes them superior to other types of tracking devices with comparable performance. Therefore, the technique is attractive for inner tracking in collider experiments, microvertex devices, or active targets for short-lived particle detection. High integration levels in the read-out based on the use of multi-pixel photon detectors and the possibility of optical multiplexing allow to reduce considerably the number of output channels, and, thus, the cost for the detector.\\\\ \\\\New optoelectronic devices have been developed and tested: the megapixel Electron Bombarded CCD (EBCCD), a high resolution image-detector having an outstanding capability of single photo-electron detection; the Vacuum Image Pipeline (VIP), a high-speed gateable pi...

Energetics of small scale turbulence in the lower stratosphere from high resolution radar measurements

Directory of Open Access Journals (Sweden)

J. Dole

Full Text Available Very high resolution radar measurements were performed in the troposphere and lower stratosphere by means of the PROUST radar. The PROUST radar operates in the UHF band (961 MHz and is located in St. Santin, France (44°39’ N, 2°12’ E. A field campaign involving high resolution balloon measurements and the PROUST radar was conducted during April 1998. Under the classical hypothesis that refractive index inhomogeneities at half radar wavelength lie within the inertial subrange, assumed to be isotropic, kinetic energy and temperature variance dissipation rates were estimated independently in the lower stratosphere. The dissipation rate of temperature variance is proportional to the dissipation rate of available potential energy. We therefore estimate the ratio of dissipation rates of potential to kinetic energy. This ratio is a key parameter of atmospheric turbulence which, in locally homogeneous and stationary conditions, is simply related to the flux Richardson number, R_f .

Key words. Meteorology and atmospheric dynamics (turbulence – Radio science (remote sensing

Temporal resolution criterion for correctly simulating relativistic electron motion in a high-intensity laser field

Energy Technology Data Exchange (ETDEWEB)

Arefiev, Alexey V. [Institute for Fusion Studies, The University of Texas, Austin, Texas 78712 (United States); Cochran, Ginevra E.; Schumacher, Douglass W. [Physics Department, The Ohio State University, Columbus, Ohio 43210 (United States); Robinson, Alexander P. L. [Central Laser Facility, STFC Rutherford-Appleton Laboratory, Didcot OX11 0QX (United Kingdom); Chen, Guangye [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2015-01-15

Particle-in-cell codes are now standard tools for studying ultra-intense laser-plasma interactions. Motivated by direct laser acceleration of electrons in sub-critical plasmas, we examine temporal resolution requirements that must be satisfied to accurately calculate electron dynamics in strong laser fields. Using the motion of a single electron in a perfect plane electromagnetic wave as a test problem, we show surprising deterioration of the numerical accuracy with increasing wave amplitude a{sub 0} for a given time-step. We go on to show analytically that the time-step must be significantly less than λ/ca{sub 0} to achieve good accuracy. We thus propose adaptive electron sub-cycling as an efficient remedy.

High Resolution Reconstruction of the Ionosphere for SAR Applications

Science.gov (United States)

Minkwitz, David; Gerzen, Tatjana; Hoque, Mainul

2014-05-01

Caused by ionosphere's strong impact on radio signal propagation, high resolution and highly accurate reconstructions of the ionosphere's electron density distribution are demanded for a large number of applications, e.g. to contribute to the mitigation of ionospheric effects on Synthetic Aperture Radar (SAR) measurements. As a new generation of remote sensing satellites the TanDEM-L radar mission is planned to improve the understanding and modelling ability of global environmental processes and ecosystem change. TanDEM-L will operate in L-band with a wavelength of approximately 24 cm enabling a stronger penetration capability compared to X-band (3 cm) or C-band (5 cm). But accompanied by the lower frequency of the TanDEM-L signals the influence of the ionosphere will increase. In particular small scale irregularities of the ionosphere might lead to electron density variations within the synthetic aperture length of the TanDEM-L satellite and in turn might result into blurring and azimuth pixel shifts. Hence the quality of the radar image worsens if the ionospheric effects are not mitigated. The Helmholtz Alliance project "Remote Sensing and Earth System Dynamics" (EDA) aims in the preparation of the HGF centres and the science community for the utilisation and integration of the TanDEM-L products into the study of the Earth's system. One significant point thereby is to cope with the mentioned ionospheric effects. Therefore different strategies towards achieving this objective are pursued: the mitigation of the ionospheric effects based on the radar data itself, the mitigation based on external information like global Total Electron Content (TEC) maps or reconstructions of the ionosphere and the combination of external information and radar data. In this presentation we describe the geostatistical approach chosen to analyse the behaviour of the ionosphere and to provide a high resolution 3D electron density reconstruction. As first step the horizontal structure of

Direct band gap measurement of Cu(In,Ga)(Se,S)2 thin films using high-resolution reflection electron energy loss spectroscopy

International Nuclear Information System (INIS)

Heo, Sung; Lee, Hyung-Ik; Park, Jong-Bong; Ko, Dong-Su; Chung, JaeGwan; Kim, KiHong; Kim, Seong Heon; Yun, Dong-Jin; Ham, YongNam; Park, Gyeong Su; Song, Taewon; Lee, Dongho; Nam, Junggyu; Kang, Hee Jae; Choi, Pyung-Ho; Choi, Byoung-Deog

2015-01-01

To investigate the band gap profile of Cu(In 1−x ,Ga x )(Se 1−y S y ) 2 of various compositions, we measured the band gap profile directly as a function of in-depth using high-resolution reflection energy loss spectroscopy (HR-REELS), which was compared with the band gap profile calculated based on the auger depth profile. The band gap profile is a double-graded band gap as a function of in-depth. The calculated band gap obtained from the auger depth profile seems to be larger than that by HR-REELS. Calculated band gaps are to measure the average band gap of the spatially different varying compositions with respect to considering its void fraction. But, the results obtained using HR-REELS are to be affected by the low band gap (i.e., out of void) rather than large one (i.e., near void). Our findings suggest an analytical method to directly determine the band gap profile as function of in-depth

High resolution resistivity measurements at the Down Ampney research site

International Nuclear Information System (INIS)

Hallam, J.R.; Jackson, P.D.; Rainsbury, M.; Raines, M.

1991-01-01

A new high resolution resistivity surveying method is described for fault detection and characterisation. The resolution is shown to be significantly higher than conventional apparent resistivity profiling when applied to geological discontinuities such as faults. Nominal fault locations have been determined to an accuracy of 0.5 m, as proven by drilling. Two dimensional profiling and image enhancement of the resulting 2-D data set indicated the possibility of subsidiary fractures and/or lateral changes within the clay to clay' fault zone. The increased resolution allows greater confidence to be placed on both the fault detection and lateral perturbations derived from processed resistance and resistivity images. (Author)

Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

KAUST Repository

Lopatin, Sergei; Cheng, Bin; Liu, Wei-Ting; Tsai, Meng-Lin; He, Jr-Hau; Chuvilin, Andrey

2017-01-01

The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

Optimization of Monochromated TEM for Ultimate Resolution Imaging and Ultrahigh Resolution Electron Energy Loss Spectroscopy

KAUST Repository

Lopatin, Sergei

2017-09-01

The performance of a monochromated transmission electron microscope with Wien type monochromator is optimized to achieve an extremely narrow energy spread of electron beam and an ultrahigh energy resolution with spectroscopy. The energy spread in the beam is improved by almost an order of magnitude as compared to specified values. The optimization involves both the monochromator and the electron energy loss detection system. We demonstrate boosted capability of optimized systems with respect to ultra-low loss EELS and sub-angstrom resolution imaging (in a combination with spherical aberration correction).

Test Particle Simulations of Electron Injection by the Bursty Bulk Flows (BBFs) using High Resolution Lyon-Feddor-Mobarry (LFM) Code

Science.gov (United States)

Eshetu, W. W.; Lyon, J.; Wiltberger, M. J.; Hudson, M. K.

2017-12-01

Test particle simulations of electron injection by the bursty bulk flows (BBFs) have been done using a test particle tracer code [1], and the output fields of the Lyon-Feddor-Mobarry global magnetohydro- dynamics (MHD) code[2]. The MHD code was run with high resolu- tion (oct resolution), and with specified solar wind conditions so as to reproduce the observed qualitative picture of the BBFs [3]. Test par- ticles were injected so that they interact with earthward propagating BBFs. The result of the simulation shows that electrons are pushed ahead of the BBFs and accelerated into the inner magnetosphere. Once electrons are in the inner magnetosphere they are further energized by drift resonance with the azimuthal electric field. In addition pitch angle scattering of electrons resulting in the violation conservation of the first adiabatic invariant has been observed. The violation of the first adiabatic invariant occurs as electrons cross a weak magnetic field region with a strong gradient of the field perturbed by the BBFs. References 1. Kress, B. T., Hudson,M. K., Looper, M. D. , Albert, J., Lyon, J. G., and Goodrich, C. C. (2007), Global MHD test particle simulations of ¿ 10 MeV radiation belt electrons during storm sudden commencement, J. Geophys. Res., 112, A09215, doi:10.1029/2006JA012218. Lyon,J. G., Fedder, J. A., and Mobarry, C.M., The Lyon- Fedder-Mobarry (LFM) Global MHD Magnetospheric Simulation Code (2004), J. Atm. And Solar-Terrestrial Phys., 66, Issue 15-16, 1333- 1350,doi:10.1016/j.jastp. Wiltberger, Merkin, M., Lyon, J. G., and Ohtani, S. (2015), High-resolution global magnetohydrodynamic simulation of bursty bulk flows, J. Geophys. Res. Space Physics, 120, 45554566, doi:10.1002/2015JA021080.

Ultrashort electron bunch length measurement with diffraction radiation deflector

Science.gov (United States)

Xiang, Dao; Huang, Wen-Hui

2007-01-01

In this paper, we propose a novel method to measure electron bunch length with a diffraction radiation (DR) deflector which is composed of a DR radiator and three beam position monitors (BPMs). When an electron beam passes through a metallic aperture which is tilted by 45 degrees with respect to its trajectory, backward DR that propagates perpendicular to the beam’s trajectory is generated which adds a transverse deflection to the beam as a result of momentum conservation. The deflection is found to be largely dependent on the bunch length and could be easily observed with a downstream BPM. Detailed investigations show that this method has wide applicability, high temporal resolution, and great simplicity.

Ultrashort electron bunch length measurement with diffraction radiation deflector

Directory of Open Access Journals (Sweden)

Dao Xiang

2007-01-01

Full Text Available In this paper, we propose a novel method to measure electron bunch length with a diffraction radiation (DR deflector which is composed of a DR radiator and three beam position monitors (BPMs. When an electron beam passes through a metallic aperture which is tilted by 45 degrees with respect to its trajectory, backward DR that propagates perpendicular to the beam’s trajectory is generated which adds a transverse deflection to the beam as a result of momentum conservation. The deflection is found to be largely dependent on the bunch length and could be easily observed with a downstream BPM. Detailed investigations show that this method has wide applicability, high temporal resolution, and great simplicity.

Assessment of engineered surfaces roughness by high-resolution 3D SEM photogrammetry

Energy Technology Data Exchange (ETDEWEB)

Gontard, L.C., E-mail: lionelcg@gmail.com [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Universidad de Cádiz, Puerto Real 11510 (Spain); López-Castro, J.D.; González-Rovira, L. [Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Escuela Superior de Ingeniería, Laboratorio de Corrosión, Universidad de Cádiz, Puerto Real 11519 (Spain); Vázquez-Martínez, J.M. [Departamento de Ingeniería Mecánica y Diseño Industrial, Escuela Superior de Ingeniería, Universidad de Cádiz, Puerto Real 11519 (Spain); Varela-Feria, F.M. [Servicio de Microscopía Centro de Investigación, Tecnología e Innovación (CITIUS), Universidad de Sevilla, Av. Reina Mercedes 4b, 41012 Sevilla (Spain); Marcos, M. [Departamento de Ingeniería Mecánica y Diseño Industrial, Escuela Superior de Ingeniería, Universidad de Cádiz, Puerto Real 11519 (Spain); and others

2017-06-15

Highlights: • We describe a method to acquire a high-angle tilt series of SEM images that is symmetrical respect to the zero tilt of the sample stage. The method can be applied in any SEM microscope. • Using the method, high-resolution 3D SEM photogrammetry can be applied on planar surfaces. • 3D models of three surfaces patterned with grooves are reconstructed with high resolution using multi-view freeware photogrammetry software as described in LC Gontard et al. Ultramicroscopy, 2016. • From the 3D models roughness parameters are measured • 3D SEM high-resolution photogrammetry is compared with two conventional methods used for roughness characetrization: stereophotogrammetry and contact profilometry. • It provides three-dimensional information with high-resolution that is out of reach for any other metrological technique. - Abstract: We describe a methodology to obtain three-dimensional models of engineered surfaces using scanning electron microscopy and multi-view photogrammetry (3DSEM). For the reconstruction of the 3D models of the surfaces we used freeware available in the cloud. The method was applied to study the surface roughness of metallic samples patterned with parallel grooves by means of laser. The results are compared with measurements obtained using stylus profilometry (PR) and SEM stereo-photogrammetry (SP). The application of 3DSEM is more time demanding than PR or SP, but it provides a more accurate representation of the surfaces. The results obtained with the three techniques are compared by investigating the influence of sampling step on roughness parameters.

Probing the electronic structure and Au–C chemical bonding in AuC2− and AuC2 using high-resolution photoelectron spectroscopy

International Nuclear Information System (INIS)

León, Iker; Yang, Zheng; Wang, Lai-Sheng

2014-01-01

We report photoelectron spectroscopy (PES) and high-resolution PE imaging of AuC 2 − at a wide range of photon energies. The ground state of AuC 2 − is found to be linear (C ∞v , 1 Σ + ) with a …8π 4 4δ 4 17σ 2 9π 4 18σ 2 valence configuration. Detachments from all the five valence orbitals of the ground state of AuC 2 − are observed at 193 nm. High-resolution PE images are obtained in the energy range from 830 to 330 nm, revealing complicated vibronic structures from electron detachment of the 18σ, 9π, and 17σ orbitals. Detachment from the 18σ orbital results in the 2 Σ + ground state of neutral AuC 2 , which, however, is bent due to strong vibronic coupling with the nearby 2 Π state from detachment of a 9π electron. The 2 Σ + – 2 Π vibronic and spin-orbit coupling results in complicated vibronic structures for the 2 Σ + and 2 Π 3/2 states with extensive bending excitations. The electron affinity of AuC 2 is measured accurately to be 3.2192(7) eV with a ground state bending frequency of 195(6) cm −1 . The first excited state ( 2 A′) of AuC 2 , corresponding to the 2 Π 3/2 state at the linear geometry, is only 0.0021 eV above the ground state ( 2 A′) and has a bending frequency of 207(6) cm −1 . The 2 Π 1/2 state, 0.2291 eV above the ground state, is linear with little geometry change relative to the anion ground state. The detachment of the 17σ orbital also results in complicated vibronic structures, suggesting again a bent state due to possible vibronic coupling with the lower 2 Π state. The spectrum at 193 nm shows the presence of a minor species with less than 2% intensity relative to the ground state of AuC 2 − . High-resolution data of the minor species reveal several vibrational progressions in the Au–C stretching mode, which are assigned to be from the metastable 3 Π 2,1,0 spin-orbit excited states of AuC 2 − to the 2 Π 3/2,1/2 spin-orbit states of neutral AuC 2 . The spin-orbit splittings of the 3 Π and 2 �

First measurements with new high-resolution gadolinium-GEM neutron detectors

CERN Document Server

Pfeiffer, Dorothea; Birch, Jens; Etxegarai, Maddi; Hall-Wilton, Richard; Höglund, Carina; Hultman, Lars; Llamas-Jansa, Isabel; Oliveri, Eraldo; Oksanen, Esko; Robinson, Linda; Ropelewski, Leszek; Schmidt, Susann; Streli, Christina; Thuiner, Patrik

2016-05-17

European Spallation Source instruments like the macromolecular diffractometer, NMX, require an excellent neutron detection efficiency, high-rate capabilities, time resolution, and an unprecedented spatial resolution in the order of a few hundred micrometers over a wide angular range of the incoming neutrons. For these instruments solid converters in combination with Micro Pattern Gaseous Detectors (MPGDs) are a promising option. A GEM detector with gadolinium converter was tested on a cold neutron beam at the IFE research reactor in Norway. The {\\mu}TPC analysis, proven to improve the spatial resolution in the case of $^{10}$B converters, is extended to gadolinium based detectors. For the first time, a Gd-GEM was successfully operated to detect neutrons with an estimated efficiency of 10% at a wavelength of 2 {\\AA} and a position resolution better than 350 {\\mu}m.

Experimental positions and lifetimes of Be-like 1s23lnl'(n=3 to 5) states of O4+ and Ne6+ ions investigated by high resolution electron spectroscopy: test of calculations

International Nuclear Information System (INIS)

Bordenave-Montesquieu, A.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.

1999-01-01

Using high resolution electron spectroscopy, positions and lifetimes of many Be-like singlet states of the 1s 2 3lnl' Rydberg series (n = 3 to 5) of oxygen and neon have been measured for the first time. This was achieved by a fitting procedure which takes into account an accurate definition of the post-collisional electron lineshapes. These states are produced after a double electron capture by multicharged ions has occurred in O 6+ (1s 2 )+He, H 2 and Ne 8+ (1s 2 )+He collisions at about 4 keV/amu collision energy. (orig.)

Atom-counting in High Resolution Electron Microscopy:TEM or STEM - That's the question.

Science.gov (United States)

Gonnissen, J; De Backer, A; den Dekker, A J; Sijbers, J; Van Aert, S

2017-03-01

In this work, a recently developed quantitative approach based on the principles of detection theory is used in order to determine the possibilities and limitations of High Resolution Scanning Transmission Electron Microscopy (HR STEM) and HR TEM for atom-counting. So far, HR STEM has been shown to be an appropriate imaging mode to count the number of atoms in a projected atomic column. Recently, it has been demonstrated that HR TEM, when using negative spherical aberration imaging, is suitable for atom-counting as well. The capabilities of both imaging techniques are investigated and compared using the probability of error as a criterion. It is shown that for the same incoming electron dose, HR STEM outperforms HR TEM under common practice standards, i.e. when the decision is based on the probability function of the peak intensities in HR TEM and of the scattering cross-sections in HR STEM. If the atom-counting decision is based on the joint probability function of the image pixel values, the dependence of all image pixel intensities as a function of thickness should be known accurately. Under this assumption, the probability of error may decrease significantly for atom-counting in HR TEM and may, in theory, become lower as compared to HR STEM under the predicted optimal experimental settings. However, the commonly used standard for atom-counting in HR STEM leads to a high performance and has been shown to work in practice. Copyright © 2017 Elsevier B.V. All rights reserved.

Theory and Practice - Measuring High-Pressure Electronic and Magnetic Properties

International Nuclear Information System (INIS)

Hemley, R.J.; Struzhkin, V.V.; Cohen, R.E.

2008-01-01

Measurements of the electronic and magnetic properties of Earth and planetary materials at high pressure play a crucial role in modern geoscience. There have been numerous advances in the field, primarily as a result of developments in diamond-anvil cell methods. In particular, synchrotron radiation techniques play an especially important role. The chapter begins with a short review of fundamental properties of the relevant materials, with emphasis on how these are altered under very high pressures and temperatures of the Earth's deep interior, followed by a discussion of different classes of electronic and magnetic excitations. Various techniques currently used for high-pressure studies are then described, beginning with optical spectroscopies, Moessbauer spectroscopy, elastic X-ray and neutron scattering, many new X-ray spectroscopy and inelastic scattering methods, transport techniques, and finally resonance methods. Selected examples of the techniques are given, with a common theme being the high P-T behavior of iron-containing oxides, silicates, and metals at conditions found throughout the Earth's interior. Applications to upper-mantle phases, 'simple' oxides, silicate perovskite and post-perovskite, volatiles, and iron and iron alloys are discussed, with an emphasis given to integrated studies utilizing a combination of different techniques to understand high P-T electronic and magnetic phenomena.

Feasibility tests of a high resolution sampling radial drift chamber

International Nuclear Information System (INIS)

Huth, J.

1985-01-01

The design concept and results of feasibility tests for a vertex detector intended for use in the TPC-PEP4/9 experiment are presented. The detector is based on a slow radial drift in dimethyl ether. High resolution localization of the avalanches at the sense wire is accomplished with nearby pickup wires and the utilization of waveform sampling electronics. The avalanche angular coordinate measurements, combined with knowledge of the electric field distribution and drift velocity permit reconstruction of the trajectory using essentially all track information. Measurements with a test chamber constructed to study characteristics of avalanche localization indicate that the recoverable track information in one centimeter of dimethyl ether at 1.5 atm is equivalent to 30 measurements of 40 μm accuracy. (orig.)

High resolution imaging of boron carbide microstructures

International Nuclear Information System (INIS)

MacKinnon, I.D.R.; Aselage, T.; Van Deusen, S.B.

1986-01-01

Two samples of boron carbide have been examined using high resolution transmission electron microscopy (HRTEM). A hot-pressed B 13 C 2 sample shows a high density of variable width twins normal to (10*1). Subtle shifts or offsets of lattice fringes along the twin plane and normal to approx.(10*5) were also observed. A B 4 C powder showed little evidence of stacking disorder in crystalline regions

Isotope specific resolution recovery image reconstruction in high resolution PET imaging

Energy Technology Data Exchange (ETDEWEB)

Kotasidis, Fotis A. [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva, Switzerland and Wolfson Molecular Imaging Centre, MAHSC, University of Manchester, M20 3LJ, Manchester (United Kingdom); Angelis, Georgios I. [Faculty of Health Sciences, Brain and Mind Research Institute, University of Sydney, NSW 2006, Sydney (Australia); Anton-Rodriguez, Jose; Matthews, Julian C. [Wolfson Molecular Imaging Centre, MAHSC, University of Manchester, Manchester M20 3LJ (United Kingdom); Reader, Andrew J. [Montreal Neurological Institute, McGill University, Montreal QC H3A 2B4, Canada and Department of Biomedical Engineering, Division of Imaging Sciences and Biomedical Engineering, King' s College London, St. Thomas’ Hospital, London SE1 7EH (United Kingdom); Zaidi, Habib [Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva (Switzerland); Geneva Neuroscience Centre, Geneva University, CH-1205 Geneva (Switzerland); Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, PO Box 30 001, Groningen 9700 RB (Netherlands)

2014-05-15

Purpose: Measuring and incorporating a scanner-specific point spread function (PSF) within image reconstruction has been shown to improve spatial resolution in PET. However, due to the short half-life of clinically used isotopes, other long-lived isotopes not used in clinical practice are used to perform the PSF measurements. As such, non-optimal PSF models that do not correspond to those needed for the data to be reconstructed are used within resolution modeling (RM) image reconstruction, usually underestimating the true PSF owing to the difference in positron range. In high resolution brain and preclinical imaging, this effect is of particular importance since the PSFs become more positron range limited and isotope-specific PSFs can help maximize the performance benefit from using resolution recovery image reconstruction algorithms. Methods: In this work, the authors used a printing technique to simultaneously measure multiple point sources on the High Resolution Research Tomograph (HRRT), and the authors demonstrated the feasibility of deriving isotope-dependent system matrices from fluorine-18 and carbon-11 point sources. Furthermore, the authors evaluated the impact of incorporating them within RM image reconstruction, using carbon-11 phantom and clinical datasets on the HRRT. Results: The results obtained using these two isotopes illustrate that even small differences in positron range can result in different PSF maps, leading to further improvements in contrast recovery when used in image reconstruction. The difference is more pronounced in the centre of the field-of-view where the full width at half maximum (FWHM) from the positron range has a larger contribution to the overall FWHM compared to the edge where the parallax error dominates the overall FWHM. Conclusions: Based on the proposed methodology, measured isotope-specific and spatially variant PSFs can be reliably derived and used for improved spatial resolution and variance performance in resolution

Isotope specific resolution recovery image reconstruction in high resolution PET imaging

International Nuclear Information System (INIS)

Kotasidis, Fotis A.; Angelis, Georgios I.; Anton-Rodriguez, Jose; Matthews, Julian C.; Reader, Andrew J.; Zaidi, Habib

2014-01-01

Purpose: Measuring and incorporating a scanner-specific point spread function (PSF) within image reconstruction has been shown to improve spatial resolution in PET. However, due to the short half-life of clinically used isotopes, other long-lived isotopes not used in clinical practice are used to perform the PSF measurements. As such, non-optimal PSF models that do not correspond to those needed for the data to be reconstructed are used within resolution modeling (RM) image reconstruction, usually underestimating the true PSF owing to the difference in positron range. In high resolution brain and preclinical imaging, this effect is of particular importance since the PSFs become more positron range limited and isotope-specific PSFs can help maximize the performance benefit from using resolution recovery image reconstruction algorithms. Methods: In this work, the authors used a printing technique to simultaneously measure multiple point sources on the High Resolution Research Tomograph (HRRT), and the authors demonstrated the feasibility of deriving isotope-dependent system matrices from fluorine-18 and carbon-11 point sources. Furthermore, the authors evaluated the impact of incorporating them within RM image reconstruction, using carbon-11 phantom and clinical datasets on the HRRT. Results: The results obtained using these two isotopes illustrate that even small differences in positron range can result in different PSF maps, leading to further improvements in contrast recovery when used in image reconstruction. The difference is more pronounced in the centre of the field-of-view where the full width at half maximum (FWHM) from the positron range has a larger contribution to the overall FWHM compared to the edge where the parallax error dominates the overall FWHM. Conclusions: Based on the proposed methodology, measured isotope-specific and spatially variant PSFs can be reliably derived and used for improved spatial resolution and variance performance in resolution

Isotope specific resolution recovery image reconstruction in high resolution PET imaging.

Science.gov (United States)

Kotasidis, Fotis A; Angelis, Georgios I; Anton-Rodriguez, Jose; Matthews, Julian C; Reader, Andrew J; Zaidi, Habib

2014-05-01

Measuring and incorporating a scanner-specific point spread function (PSF) within image reconstruction has been shown to improve spatial resolution in PET. However, due to the short half-life of clinically used isotopes, other long-lived isotopes not used in clinical practice are used to perform the PSF measurements. As such, non-optimal PSF models that do not correspond to those needed for the data to be reconstructed are used within resolution modeling (RM) image reconstruction, usually underestimating the true PSF owing to the difference in positron range. In high resolution brain and preclinical imaging, this effect is of particular importance since the PSFs become more positron range limited and isotope-specific PSFs can help maximize the performance benefit from using resolution recovery image reconstruction algorithms. In this work, the authors used a printing technique to simultaneously measure multiple point sources on the High Resolution Research Tomograph (HRRT), and the authors demonstrated the feasibility of deriving isotope-dependent system matrices from fluorine-18 and carbon-11 point sources. Furthermore, the authors evaluated the impact of incorporating them within RM image reconstruction, using carbon-11 phantom and clinical datasets on the HRRT. The results obtained using these two isotopes illustrate that even small differences in positron range can result in different PSF maps, leading to further improvements in contrast recovery when used in image reconstruction. The difference is more pronounced in the centre of the field-of-view where the full width at half maximum (FWHM) from the positron range has a larger contribution to the overall FWHM compared to the edge where the parallax error dominates the overall FWHM. Based on the proposed methodology, measured isotope-specific and spatially variant PSFs can be reliably derived and used for improved spatial resolution and variance performance in resolution recovery image reconstruction. The

High-resolution spectroscopy for Doppler-broadening ion temperature measurements of implosions at the National Ignition Facility

Energy Technology Data Exchange (ETDEWEB)

Koch, J. A.; Stewart, R. E.; Beiersdorfer, P.; Shepherd, R.; Schneider, M. B.; Miles, A. R.; Scott, H. A.; Smalyuk, V. A.; Hsing, W. W. [Lawrence Livermore National Laboratory, P.O. Box 808, L-493, Livermore, California 94550 (United States)

2012-10-15

Future implosion experiments at the national ignition facility (NIF) will endeavor to simultaneously measure electron and ion temperatures with temporal and spatial resolution in order to explore non-equilibrium temperature distributions and their relaxation toward equilibrium. In anticipation of these experiments, and with understanding of the constraints of the NIF facility environment, we have explored the use of Doppler broadening of mid-Z dopant emission lines, such as krypton He-{alpha} at 13 keV, as a diagnostic of time- and potentially space-resolved ion temperature. We have investigated a number of options analytically and with numerical raytracing, and we have identified several promising candidate spectrometer designs that meet the expected requirements of spectral and temporal resolution and data signal-to-noise ratio for gas-filled exploding pusher implosions, while providing maximum flexibility for use on a variety of experiments that potentially include burning plasma.

High resolution electron microscopy studies of interfaces between Al2O3 substrates and MBE grown Nb films

International Nuclear Information System (INIS)

Mayer, J.; Ruhle, M.; Dura, J.; Flynn, C.P.

1991-01-01

This paper reports on single crystal niobium films grown by Molecular Beam Epitaxy (MBE) on (001) S sapphire substrates. Cross-sectional specimens with thickness of 2 O 3 interface could be investigated by high resolution electron microscopy (HREM). The orientation relationship between the metal film and the ceramic substrate was verified by selected area diffraction: (111) Nb parallel (0001) S and [1 bar 10] Nb parallel [2 bar 1 bar 10] S . The atomistic structure of the interface was identified by HREM

Comparison of high-resolution Scheimpflug and high-frequency ultrasound biomicroscopy to anterior-segment OCT corneal thickness measurements

Directory of Open Access Journals (Sweden)

Kanellopoulos AJ

2013-11-01

Full Text Available Anastasios John Kanellopoulos,1,2 George Asimellis1 1Laservision.gr Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USA Background: The purpose of this study was to compare and correlate central corneal thickness in healthy, nonoperated eyes with three advanced anterior-segment imaging systems: a high-resolution Scheimpflug tomography camera (Oculyzer II, a spectral-domain anterior-segment optical coherence tomography (AS-OCT system, and a high-frequency ultrasound biomicroscopy (HF-UBM system. Methods: Fifty eyes randomly selected from 50 patients were included in the study. Inclusion criteria were healthy, nonoperated eyes examined consecutively by the same examiner. Corneal imaging was performed by three different methods, ie, Oculyzer II, spectral-domain AS-OCT, and FH-UBM. Central corneal thickness measurements were compared using scatter diagrams, Bland-Altman plots (with bias and 95% confidence intervals, and two-paired analysis. Results: The coefficient of determination (r2 between the Oculyzer II and AS-OCT measurements was 0.895. Likewise, the coefficient was 0.893 between the Oculyzer II and HF-UBM and 0.830 between the AS-OCT and HF-UBM. The trend line coefficients of linearity were 0.925 between the Oculyzer II and the AS-OCT, 1.006 between the Oculyzer II and HF-UBM, and 0.841 between the AS-OCT and HF-UBM. The differences in average corneal thickness between the three pairs of CCT measurements were –6.86 µm between the Oculyzer II and HF-UBM, –12.20 µm between the AS-OCT and Oculyzer II, and +19.06 µm between the HF-UBM and AS-OCT. Conclusion: The three methods used for corneal thickness measurement are highly correlated. Compared with the Scheimplug and ultrasound devices, the AS-OCT appears to report a more accurate, but overally thinner corneal pachymetry. Keywords: anterior eye segment, high-frequency ultrasound biomicroscopy, optical coherence tomography, high-resolution Pentacam

Strain mapping for the semiconductor industry by dark-field electron holography and nanobeam electron diffraction with nm resolution

International Nuclear Information System (INIS)

Cooper, David; Hartmann, Jean Michel; Carron, Veronique; Béché, Armand; Rouvière, Jean-Luc

2010-01-01

There is a requirement of the semiconductor industry to measure strain in semiconductor devices with nm-scale resolution. Here we show that dark-field electron holography and nanobeam electron diffraction (NBED) are both complementary techniques that can be used to determine the strain in these devices. We show two-dimensional strain maps acquired by dark holography and line profiles that have been acquired by NBED of recessed SiGe sources and drains with a variety of different gate lengths and Ge concentrations. We have also used dark-field electron holography to measure the evolution in strain during the silicidation process, showing that this can reduce the applied uniaxial compressive strain in the conduction channel by up to a factor of 3

Dielectronic recombination measurements using the Electron Beam Ion Trap

International Nuclear Information System (INIS)

Knapp, D.A.

1991-01-01

We have used the Electron Beam Ion Trap at LLNL to study dielectronic recombination in highly charged ions. Our technique is unique because we observe the x-rays from dielectronic recombination at the same time we see x-rays from all other electron-ion interactions. We have recently taken high-resolution, state-selective data that resolves individual resonances

High resolution time-of-flight measurements in small and large scintillation counters

International Nuclear Information System (INIS)

D'Agostini, G.; Marini, G.; Martellotti, G.; Massa, F.; Rambaldi, A.; Sciubba, A.

1981-01-01

In a test run, the experimental time-of-flight resolution was measured for several different scintillation counters of small (10 x 5 cm 2 ) and large (100 x 15 cm 2 and 75 x 25 cm 2 ) area. The design characteristics were decided on the basis of theoretical Monte Carlo calculations. We report results using twisted, fish-tail, and rectangular light- guides and different types of scintillator (NE 114 and PILOT U). Time resolution up to approx. equal to 130-150 ps fwhm for the small counters and up to approx. equal to 280-300 ps fwhm for the large counters were obtained. The spatial resolution from time measurements in the large counters is also reported. The results of Monte Carlo calculations on the type of scintillator, the shape and dimensions of the light-guides, and the nature of the external wrapping surfaces - to be used in order to optimize the time resolution - are also summarized. (orig.)

An improved experimental scheme for simultaneous measurement of high-resolution zero electron kinetic energy (ZEKE) photoelectron and threshold photoion (MATI) spectra

Science.gov (United States)

Michels, François; Mazzoni, Federico; Becucci, Maurizio; Müller-Dethlefs, Klaus

2017-10-01

An improved detection scheme is presented for threshold ionization spectroscopy with simultaneous recording of the Zero Electron Kinetic Energy (ZEKE) and Mass Analysed Threshold Ionisation (MATI) signals. The objective is to obtain accurate dissociation energies for larger molecular clusters by simultaneously detecting the fragment and parent ion MATI signals with identical transmission. The scheme preserves an optimal ZEKE spectral resolution together with excellent separation of the spontaneous ion and MATI signals in the time-of-flight mass spectrum. The resulting improvement in sensitivity will allow for the determination of dissociation energies in clusters with substantial mass difference between parent and daughter ions.

On some aspects of high voltage electron microscopy

International Nuclear Information System (INIS)

Jouffrey, B.; Trinquier, J.

1987-01-01

The present paper deals with high voltage electron microscopy (HVEM). It is an overview on this domain due to the pionneer work of G. Dupouy which has permitted to perform a new kind of electron microscopy. Since this time, HVEM has shown its interest in high resolution, irradiations, chemical analysis, in situ experiments

Resolution Versus Error for Computational Electron Microscopy

Energy Technology Data Exchange (ETDEWEB)

Luzi, Lorenzo; Stevens, Andrew; Yang, Hao; Browning, Nigel D.

2017-07-01

Images that are collected via scanning transmission electron microscopy (STEM) can be undersampled to avoid damage to the specimen while maintaining resolution [1, 2]. We have used BPFA to impute missing data and reduce noise [3]. The reconstruction is typically evaluated using the peak signal-to-noise ratio (PSNR). This measure is too conservative for STEM images and we propose that the Fourier ring correlation (FRC) is used instead to evaluate the reconstruction. We are not concerned with exact reconstruction of the truth image, and therefore PSNR is a conservative estimation of the quality of the reconstruction. Instead, we are concerned with the visual resolution of the image and whether atoms can be distinguished. We have evaluated the reconstruction of a simulated STEM image using the FRC and compared the results with the PSNR measurements. The FRC captures the resolution of the image and is not affected by a large MSE if the atom peaks are still distinguishable. The noisy and reconstructed images are shown in Figure 1. The simulated STEM image was sampled at 100%, 80%, 40%, and 20% of the original pixels to simulate an undersampled scan. The reconstruction was done using BPFA with a patch size of 10 x 10 and no overlapping patches. Not having overlapping patches produces inferior results but they are still acceptable. The dictionary size is 64 and 30 iterations were completed during each reconstruction. The 100% image was denoised instead of reconstructed. Poisson noise was applied to the simulated image with λ values of 500, 50, and 5 to simulate lower imaging dose. The original simulated STEM image was also included in our calculations and was generated using a dose of 1000. The simulated STEM image is 100 by 100 pixels and has essentially no high frequency components. The image reconstruction tends to smooth the data, also resulting in no high frequency components. This causes the FRC of the two images to be large at higher resolutions and may be

High-resolution visualization of Pseudomonas aeruginosa PAO1 biofilms by freeze-substitution transmission electron microscopy.

Science.gov (United States)

Hunter, Ryan C; Beveridge, Terry J

2005-11-01

High-pressure freeze-substitution and transmission electron microscopy have been used for high-resolution imaging of the natural structure of a gram-negative biofilm. Unlike more conventional embedding techniques, this method confirms many of the observations seen by confocal microscopy but with finer structural detail. It further reveals that there is a structural complexity to biofilms at both the cellular and extracellular matrix levels that has not been seen before. Different domains of healthy and lysed cells exist randomly dispersed within a single biofilm as well as different structural organizations of exopolymers. Particulate matter is suspended within this network of fibers and appears to be an integral part of the exopolymeric substance (EPS). O-side chains extending from the outer membrane are integrated into EPS polymers so as to form a continuum. Together, the results support the concept of physical microenvironments within biofilms and show a complexity that was hitherto unknown.

40 keV atomic resolution TEM

International Nuclear Information System (INIS)

Bell, David C.; Russo, Christopher J.; Kolmykov, Dmitry V.

2012-01-01

Here we present the first atomic resolution TEM imaging at 40 keV using an aberration-corrected, monochromated source TEM. Low-voltage High-Resolution Electron Microscopy (LVHREM) has several advantages, including increased cross-sections for inelastic and elastic scattering, increased contrast per electron and improved spectroscopy efficiency, decreased delocalization effects and reduced knock-on damage. Together, these often improve the contrast to damage ratio obtained on a large class of samples. Third-order aberration correction now allows us to operate the TEM at low energies while retaining atomic resolution, which was previously impossible. At low voltage the major limitation to resolution becomes the chromatic aberration limit. We show that using a source monochromator we are able to reduce the effect of chromatic aberration and achieve a usable high-resolution limit at 40 keV to less than 1 Å. We show various materials' examples of the application of the technique to image graphene and silicon, and compare atomic resolution images with electron multislice simulations. -- Highlights: ► We present the first atomic resolution images recorded at 40 keV using an aberration-corrected, monochromated TEM. ► We show information transfer measured to better than 1 Å. ► At 40 keV an aberration-corrected monochromated TEM is limited by fifth-order spherical aberration. ► We show that using a monochromator the effect of chromatic aberration is reduced to enable high resolution imaging. ► Low voltage high resolution electron microscopy will be beneficial for imaging the organic/inorganic materials interface.

Front-end electronics for accurate energy measurement of double beta decays

International Nuclear Information System (INIS)

Gil, A.; Díaz, J.; Gómez-Cadenas, J.J.; Herrero, V.; Rodriguez, J.; Serra, L.; Toledo, J.; Esteve, R.; Monzó, J.M.; Monrabal, F.; Yahlali, N.

2012-01-01

NEXT, a double beta decay experiment that will operate in Canfranc Underground Laboratory (Spain), aims at measuring the neutrinoless double-β decay of the 136Xe isotope using a TPC filled with enriched Xenon gas at high pressure operated in electroluminescence mode. One technological challenge of the experiment is to achieve resolution better than 1% in the energy measurement using a plane of UV sensitive photomultipliers readout with appropriate custom-made front-end electronics. The front-end is designed to be sensitive to the single photo-electron to detect the weak primary scintillation light produced in the chamber, and also to be able to cope with the electroluminescence signal (several hundred times higher and with a duration of microseconds). For efficient primary scintillation detection and precise energy measurement of the electroluminescent signals the front-end electronics features low noise and adequate amplification. The signal shaping provided allows the digitization of the signals at a frequency as low as 40 MHz.

High-Resolution UV Relay Lens for Particle Size Distribution Measurements Using Holography

Energy Technology Data Exchange (ETDEWEB)

Malone, Robert M.; Capelle, Gene A.; Frogget, Brent C.; Grover, Mike; Kaufman, Morris I.; Pazuchanics, Peter; Sorenson, Danny S.; Stevens, Gerald D.; Tibbits, Aric; Turley, William D.

2008-08-29

Shock waves passing through a metal sample can produce ejecta particulates at a metal-vacuum interface. Holography records particle size distributions by using a high-power, short-pulse laser to freeze particle motion. The sizes of the ejecta particles are recorded using an in-line Fraunhofer holography technique. Because the holographic plate would be destroyed in an energetic environment, a high-resolution lens has been designed to relay the interference fringes to a safe environment. Particle sizes within a 12-mm-diameter, 5-mm-thick volume are recorded onto holographic film. To achieve resolution down to 0.5 μm, ultraviolet laser (UV) light is needed. The design and assembly of a nine-element lens that achieves >2000 lp/mm resolution and operates at f/0.89 will be described. To set up this lens system, a doublet lens is temporarily attached that enables operation with 532-nm laser light and 1100 lp/mm resolution. Thus, the setup and alignment are performed with green light, but the dynamic recording is done with UV light. During setup, the 532-nm beam provides enough focus shift to accommodate the placement of a resolution target outside the ejecta volume; this resolution target does not interfere with the calibrated wires and pegs surrounding the ejecta volume. A television microscope archives images of resolution patterns that prove that the calibration wires, interference filter, holographic plate, and relay lenses are in their correct positions. Part of this lens is under vacuum, at the point where the laser illumination passes through a focus. Alignment and tolerancing of this high-resolution lens will be presented, and resolution variation through the 5-mm depth of field will be discussed.

Non-Proportionality of Electron Response and Energy Resolution of Compton Electrons in Scintillators

Science.gov (United States)

Swiderski, L.; Marcinkowski, R.; Szawlowski, M.; Moszynski, M.; Czarnacki, W.; Syntfeld-Kazuch, A.; Szczesniak, T.; Pausch, G.; Plettner, C.; Roemer, K.

2012-02-01

Non-proportionality of light yield and energy resolution of Compton electrons in three scintillators (LaBr3:Ce, LYSO:Ce and CsI:Tl) were studied in a wide energy range from 10 keV up to 1 MeV. The experimental setup was comprised of a High Purity Germanium detector and tested scintillators coupled to a photomultiplier. Probing the non-proportionality and energy resolution curves at different energies was obtained by changing the position of various radioactive sources with respect to both detectors. The distance between both detectors and source was kept small to make use of Wide Angle Compton Coincidence (WACC) technique, which allowed us to scan large range of scattering angles simultaneously and obtain relatively high coincidence rate of 100 cps using weak sources of about 10 μCi activity. The results are compared with those obtained by direct irradiation of the tested scintillators with gamma-ray sources and fitting the full-energy peaks.

A design for a subminiature, low energy scanning electron microscope with atomic resolution

International Nuclear Information System (INIS)

Eastham, D. A.; Edmondson, P.; Greene, S.; Donnelly, S.; Olsson, E.; Svensson, K.; Bleloch, A.

2009-01-01

We describe a type of scanning electron microscope that works by directly imaging the electron field-emission sites on a nanotip. Electrons are extracted from the nanotip through a nanoscale aperture, accelerated in a high electric field, and focused to a spot using a microscale Einzel lens. If the whole microscope (accelerating section and lens) and the focal length are both restricted in size to below 10 μm, then computer simulations show that the effects of aberration are extremely small and it is possible to have a system with approximately unit magnification at electron energies as low as 300 eV. Thus a typical emission site of 1 nm diameter will produce an image of the same size, and an atomic emission site will give a resolution of 0.1-0.2 nm (1-2 A). Also, because the beam is not allowed to expand beyond 100 nm in diameter, the depth of field is large and the contribution to the beam spot size from chromatic aberrations is less than 0.02 nm (0.2 A) for 500 eV electrons. Since it is now entirely possible to make stable atomic sized emitters (nanopyramids), it is expected that this instrument will have atomic resolution. Furthermore the brightness of the beam is determined only by the field emission and can be up to 1x10 6 times larger than in a typical (high energy) electron microscope. The advantages of this low energy, bright-beam electron microscope with atomic resolution are described and include the possibility of it being used to rapidly sequence the human genome from a single strand of DNA as well as being able to identify atomic species directly from the elastic scattering of electrons

High-resolution parallel electron energy-loss spectroscopy of MnL2,3-edges in inorganic manganese compounds

International Nuclear Information System (INIS)

Garvie, L.A.J.; Craven, A.J.

1994-01-01

Parallel electron energy-loss spectroscopy (PEELS) in a scanning transmission electron microscope (STEM) was used to record the Mn L 2,3 -edges from a range of natural and synthetic manganese containing materials, covering valences 0, II, III, IV and VII, with an energy resolution of ca. 0.5 eV. The Mn L 2,3 electron-loss near-edge structure (ELNES) of these edges provided a sensitive fingerprint of its valence. The Mn 2+ L 2,3 -edges show little sensitivity to the local site symmetry of the ligands surrounding the manganese. This is illustrated by comparing the Mn L 2,3 -edges from 4-, 6-and 8-fold coordinated Mn 2+ . In contrast, the Mn L 3 -edges from Mn 3+ and Mn 4+ containing minerals exhibited ELNES that are interpreted in terms of a crystals-field splitting of the 3d electrons, governed by the symmetry of the surrounding ligands. The Mn L 3 -edges for octahedrally coordinated Mn 2+ , Mn 3+ and Mn 4+ showed variations in their ELNES that were sensitive to the crystal-field strength. The crystal-field strength (10Q) was measured from these edges and compared very well with published optically determinted values. The magnitude of 10Dq measured from the Mn L 3 -edges and their O K-edge prepeaks of the manganese oxides were almost identical. This further confirms that the value of 10Dq measured at the Mn L 3 -edge is correct. Selected spectra are compared with theoretical 2p atomic multiplet spectra and the differences and similarities are explained in terms of the covalency and site symmetry of the manganese. The Mn L 3 -edges allow the valence of the manganese to be ascertained, even in multivalent state materials, and can also be used to dtermin 10Dq. (orig.)

High-resolution X-ray diffraction studies of multilayers

DEFF Research Database (Denmark)

Christensen, Finn Erland; Hornstrup, Allan; Schnopper, H. W.

1988-01-01

High-resolution X-ray diffraction studies of the perfection of state-of-the-art multilayers are presented. Data were obtained using a triple-axis perfect-crystal X-ray diffractometer. Measurements reveal large-scale figure errors in the substrate. A high-resolution triple-axis set up is required...

Quantitative measurement of zinc secretion from pancreatic islets with high temporal resolution using droplet-based microfluidics.

Science.gov (United States)

Easley, Christopher J; Rocheleau, Jonathan V; Head, W Steven; Piston, David W

2009-11-01

We assayed glucose-stimulated insulin secretion (GSIS) from live, murine islets of Langerhans in microfluidic devices by the downstream formation of aqueous droplets. Zinc ions, which are cosecreted with insulin from beta-cells, were quantitatively measured from single islets with high temporal resolution using a fluorescent indicator, FluoZin-3. Real-time storage of secretions into droplets (volume of 0.470 +/- 0.009 nL) effectively preserves the temporal chemical information, allowing reconstruction of the secretory time record. The use of passive flow control within the device removes the need for syringe pumps, requiring only a single hand-held syringe. Under stimulatory glucose levels (11 mM), bursts of zinc as high as approximately 800 fg islet(-1) min(-1) were measured. Treatment with diazoxide effectively blocked zinc secretion, as expected. High temporal resolution reveals two major classes of oscillations in secreted zinc, with predominate periods at approximately 20-40 s and approximately 5-10 min. The more rapid oscillation periods match closely with those of intraislet calcium oscillations, while the slower oscillations are consistent with insulin pulses typically measured in bulk islet experiments or in the bloodstream. This droplet sampling technique should be widely applicable to time-resolved cellular secretion measurements, either in real-time or for postprocessing.

High Resolution Higher Energy X-ray Microscope for Mesoscopic Materials

International Nuclear Information System (INIS)

Snigireva, I; Snigirev, A

2013-01-01

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

High resolution NMR imaging using a high field yokeless permanent magnet.

Science.gov (United States)

Kose, Katsumi; Haishi, Tomoyuki

2011-01-01

We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 µm](2)) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging.

High resolution NMR imaging using a high field yokeless permanent magnet

International Nuclear Information System (INIS)

Kose, Katsumi; Haishi, Tomoyuki

2011-01-01

We measured the homogeneity and stability of the magnetic field of a high field (about 1.04 tesla) yokeless permanent magnet with 40-mm gap for high resolution nuclear magnetic resonance (NMR) imaging. Homogeneity was evaluated using a 3-dimensional (3D) lattice phantom and 3D spin-echo imaging sequences. In the central sphere (20-mm diameter), peak-to-peak magnetic field inhomogeneity was about 60 ppm, and the root-mean-square was 8 ppm. We measured room temperature, magnet temperature, and NMR frequency of the magnet simultaneously every minute for about 68 hours with and without the thermal insulator of the magnet. A simple mathematical model described the magnet's thermal property. Based on magnet performance, we performed high resolution (up to [20 μm] 2 ) imaging with internal NMR lock sequences of several biological samples. Our results demonstrated the usefulness of the high field small yokeless permanent magnet for high resolution NMR imaging. (author)

The investigation of Martian dune fields using very high resolution photogrammetric measurements and time series analysis

Science.gov (United States)

Kim, J.; Park, M.; Baik, H. S.; Choi, Y.

2016-12-01

At the present time, arguments continue regarding the migration speeds of Martian dune fields and their correlation with atmospheric circulation. However, precisely measuring the spatial translation of Martian dunes has rarely conducted only a very few times Therefore, we developed a generic procedure to precisely measure the migration of dune fields with recently introduced 25-cm resolution High Resolution Imaging Science Experimen (HIRISE) employing a high-accuracy photogrammetric processor and sub-pixel image correlator. The processor was designed to trace estimated dune migration, albeit slight, over the Martian surface by 1) the introduction of very high resolution ortho images and stereo analysis based on hierarchical geodetic control for better initial point settings; 2) positioning error removal throughout the sensor model refinement with a non-rigorous bundle block adjustment, which makes possible the co-alignment of all images in a time series; and 3) improved sub-pixel co-registration algorithms using optical flow with a refinement stage conducted on a pyramidal grid processor and a blunder classifier. Moreover, volumetric changes of Martian dunes were additionally traced by means of stereo analysis and photoclinometry. The established algorithms have been tested using high-resolution HIRISE images over a large number of Martian dune fields covering whole Mars Global Dune Database. Migrations over well-known crater dune fields appeared to be almost static for the considerable temporal periods and were weakly correlated with wind directions estimated by the Mars Climate Database (Millour et al. 2015). Only over a few Martian dune fields, such as Kaiser crater, meaningful migration speeds (>1m/year) compared to phtotogrammetric error residual have been measured. Currently a technical improved processor to compensate error residual using time series observation is under developing and expected to produce the long term migration speed over Martian dune

High-Resolution Two-Dimensional Optical Spectroscopy of Electron Spins

Directory of Open Access Journals (Sweden)

M. Salewski

2017-08-01

Full Text Available Multidimensional coherent optical spectroscopy is one of the most powerful tools for investigating complex quantum mechanical systems. While it was conceived decades ago in magnetic resonance spectroscopy using microwaves and radio waves, it has recently been extended into the visible and UV spectral range. However, resolving MHz energy splittings with ultrashort laser pulses still remains a challenge. Here, we analyze two-dimensional Fourier spectra for resonant optical excitation of resident electrons to localized trions or donor-bound excitons in semiconductor nanostructures subject to a transverse magnetic field. Particular attention is devoted to Raman coherence spectra, which allow one to accurately evaluate tiny splittings of the electron ground state and to determine the relaxation times in the electron spin ensemble. A stimulated steplike Raman process induced by a sequence of two laser pulses creates a coherent superposition of the ground-state doublet which can be retrieved only optically because of selective excitation of the same subensemble with a third pulse. This provides the unique opportunity to distinguish between different complexes that are closely spaced in energy in an ensemble. The related experimental demonstration is based on photon-echo measurements in an n-type CdTe/(Cd,MgTe quantum-well structure detected by a heterodyne technique. The difference in the sub-μeV range between the Zeeman splittings of donor-bound electrons and electrons localized at potential fluctuations can be resolved even though the homogeneous linewidth of the optical transitions is larger by 2 orders of magnitude.

Chromatic Modulator for High Resolution CCD or APS Devices

Science.gov (United States)

Hartley, Frank T. (Inventor); Hull, Anthony B. (Inventor)

2003-01-01

A system for providing high-resolution color separation in electronic imaging. Comb drives controllably oscillate a red-green-blue (RGB) color strip filter system (or otherwise) over an electronic imaging system such as a charge-coupled device (CCD) or active pixel sensor (APS). The color filter is modulated over the imaging array at a rate three or more times the frame rate of the imaging array. In so doing, the underlying active imaging elements are then able to detect separate color-separated images, which are then combined to provide a color-accurate frame which is then recorded as the representation of the recorded image. High pixel resolution is maintained. Registration is obtained between the color strip filter and the underlying imaging array through the use of electrostatic comb drives in conjunction with a spring suspension system.

Measuring the hydrogen/deuterium exchange of proteins at high spatial resolution by mass spectrometry

DEFF Research Database (Denmark)

Rand, Kasper Dyrberg; Zehl, Martin; Jørgensen, Thomas J D

2014-01-01

, and eventually all of the protecting hydrogen bonds will transiently break as the protein-according to thermodynamic principles-cycles through partially unfolded states that correspond to excited free energy levels. As a result, all of the backbone amides will eventually become temporarily solvent....../dysfunction and conformational dynamics requires in many cases higher resolution and ultimately single-residue resolution. In this Account, we summarize our efforts to achieve single-residue deuterium levels in proteins by electron-based or laser-induced gas-phase fragmentation methods. A crucial analytical requirement...

High-resolution absorption measurements of NH₃ at high temperatures: 500–2100cm⁻¹

DEFF Research Database (Denmark)

Barton, Emma J.; Yurchenko, Sergei N.; Tennyson, Jonathan

2015-01-01

High-resolution absorption spectra of NH3 in the region 500–2100 cm -1 at temperatures up to1027 1C and approximately atmospheric pressure (1013±20 mbar) are measured. NH3 concentrations of 1000 ppm,0.5% and 1% in volume fraction were used in the measurements. Spectra are recorded in high tempera...... to a variational line list, BYTe, and experimental energy levels determined using the MARVEL procedure. Approximately 2000 lines have been assigned, of which 851are newly assigned to mainly hot bands involving vibrational states as high as v2=5....

Atomic resolution imaging of YAlO{sub 3}: Ce in the chromatic and spherical aberration corrected PICO electron microscope

Energy Technology Data Exchange (ETDEWEB)

Jin, Lei [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Barthel, Juri [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, 52074 Aachen (Germany); Jia, Chun-Lin [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); Urban, Knut W., E-mail: k.urban@fz-juelich.de [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Jülich-Aachen Research Alliance (JARA), Forschungszentrum Jülich GmbH, 52425 Jülich, (Germany); School of Electronic and Information Engineering and State Key Laboratory for Mechanical Behaviour of Materials, Xi' an Jiaotong University, Xi' an 710049 (China)

2017-05-15

Highlights: • First time resolution of 57 pm atom separations by HRTEM with 200 keV electrons. • Quantification of the image spread by absolute matching of experiment and simulation. • An information limit of 52 pm is deduced from the determined image spread. • Substantial deviations from the bulk structure are observed for the ultra-thin sample. - Abstract: The application of combined chromatic and spherical aberration correction in high-resolution transmission electron microscopy enables a significant improvement of the spatial resolution down to 50 pm. We demonstrate that such a resolution can be achieved in practice at 200 kV. Diffractograms of images of gold nanoparticles on amorphous carbon demonstrate corresponding information transfer. The Y atom pairs in [010] oriented yttrium orthoaluminate are successfully imaged together with the Al and the O atoms. Although the 57 pm pair separation is well demonstrated separations between 55 pm and 80 pm are measured. This observation is tentatively attributed to structural relaxations and surface reconstruction in the very thin samples used. Quantification of the resolution limiting effective image spread is achieved based on an absolute match between experimental and simulated image intensity distributions.

A Thin detector with ionization tubes for high energy electrons and photons

International Nuclear Information System (INIS)

Amatuni, Ts. A.; Denisov, S.P.; Krasnokutsky, R.N.; Lebedenko, V.N.; Shuvalov, R.S.

1981-01-01

A possibility to measure the energy of electrons and photons with a simple detector, consisting of a lead convertor and ionization tubes filled with pure argon, has been studied. The measurements have been performed in a 26.6 GeV electron beam. The best energy resolution approximately 16% was achieved for the convertor thickness 40 mm and argon pressure > 20 atm. The performance of the detector in magnetic field up to 16 kGs has been also studied. It turned out that the mean pulse height rises approximately linearly with increasing magnetic field and becomes flat at H approximately 10 kGs. This behaviour is the same for magnetic field perpendicular and parallel with respect to the ionization tubes. The energy resolution depends weakly on the magnetic field. Ionization tubes filled with argon or xenon under high pressure may be used for minimum ionizing particle detection [ru

Ultrashort and coherent single-electron pulses for diffraction at ultimate resolutions

International Nuclear Information System (INIS)

Kirchner, Friedrich Oscar

2013-01-01

Ultrafast electron diffraction is a powerful tool for studying structural dynamics with femtosecond temporal and sub-aangstroem spatial resolutions. It benefits from the high scattering cross-sections of electrons compared X-rays and allows the examination of thin samples, surfaces and gases. One of the main challenges in ultrafast electron diffraction is the generation of electron pulses with a short duration and a large transverse coherence. The former limits the temporal resolution of the experiment while the latter determines the maximum size of the scattering structures that can be studied. In this work, we strive to push the limits of electron diffraction towards higher temporal and spatial resolutions. The decisive step in our approach is to eliminate all detrimental effects caused by Coulomb repulsion between the electrons by reducing the number of electrons per pulse to one. In this situation, the electrons' longitudinal and transverse velocity distributions are determined solely by the photoemission process. By reducing the electron source size on the photocathode, we make use of the small transverse velocity spread to produce electron pulses with a transverse coherence length of 20 nm, which is about an order of magnitude larger than the reported values for comparable experiments. The energy distribution of an ensemble of single-electron pulses from a photoemission source is directly linked to the mismatch between the photon energy and the cathode's work function. This excess energy can be reduced by using a photon energy close to the material's work function. Using a tunable source of ultraviolet pulses, we demonstrate the reduction of the velocity spread of the electrons, resulting in a shorter duration of the electron pulses. The reduced electron pulse durations achieved by a tunable excitation or by other approaches require new characterization techniques for electron pulses. We developed a novel method for the characterization of electron pulses at

High-resolution measurement of the {sup 16}O({gamma},pn) reaction

Energy Technology Data Exchange (ETDEWEB)

Isaksson, L.

1996-10-01

The {sup 16}O({gamma},pn) reaction has been measured with a resolution high enough to resolve individual low-lying states in the residual {sup 14}N nucleus. Partial cross-sections, available to the acceptance of the detector system, have been extracted for the individual states, and compared to a recent calculation based on absorption on one-pion exchange currents and the {Delta} resonance current. The experiment was performed at the Maxlab accelerator laboratory in Lund, Sweden, using tagged photons at an energy of 67 - 76 MeV. The proton detector angular range was 60 - 100 deg and the corresponding for the neutron detector 81 - 103 deg. A missing energy resolution of 1.5 MeV was obtained. The relative population of the states in the residual {sup 14}N nucleus indicates that the reaction takes place predominantly on proton-neutron pairs coupled to (J{sup {pi}},T) = (1{sup +},0). The cross-section for absorption on (0{sup +},1) pairs is strongly suppressed. Furthermore, the relative population of the states indicates that both L=0 and L=2 pairs participate in the reaction. 45 refs.

High-resolution measurement and mapping of tungstate in waters, soils and sediments using the low-disturbance DGT sampling technique

Energy Technology Data Exchange (ETDEWEB)

Guan, Dong-Xing [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Williams, Paul N. [Institute for Global Food Security, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL (United Kingdom); Xu, Hua-Cheng [State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008 (China); Li, Gang [Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021 (China); Luo, Jun, E-mail: esluojun@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Ma, Lena Q. [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Soil and Water Science Department, University of Florida, Gainesville, FL 32611 (United States)

2016-10-05

Highlights: • Two high-resolution diffusive gradients in thin-films samplers were characterized. • For the first time DGT was applied to study the bioavailability of W in soils. • 1D and 2D high resolution profiling of W fluxes across the SWI were obtained. • The apparent diffusion W fluxes across two micro-interfaces were calculated. - Abstract: Increasing tungsten (W) use for industrial and military applications has resulted in greater W discharge into natural waters, soils and sediments. Risk modeling of W transport and fate in the environment relies on measurement of the release/mobilization flux of W in the bulk media and the interfaces between matrix compartments. Diffusive gradients in thin-films (DGT) is a promising passive sampling technique to acquire such information. DGT devices equipped with the newly developed high-resolution binding gels (precipitated zirconia, PZ, or ferrihydrite, PF, gels) or classic/conventional ferrihydrite slurry gel were comprehensively assessed for measuring W in waters. {sup Ferrihydrite}DGT can measure W at various ionic strengths (0.001–0.5 mol L{sup −1} NaNO{sub 3}) and pH (4–8), while {sup PZ}DGT can operate across slightly wider environmental conditions. The three DGT configurations gave comparable results for soil W measurement, showing that typically W resupply is relatively poorly sustained. 1D and 2D high-resolution W profiling across sediment—water and hotspot—bulk media interfaces from Lake Taihu were obtained using {sup PZ}DGT coupled with laser ablation ICP–MS measurement, and the apparent diffusion fluxes across the interfaces were calculated using a numerical model.

High resolution measurements and study of the neutron inelastic scattering reaction on 56Fe

International Nuclear Information System (INIS)

Dupont, E.

1998-01-01

High resolution measures of neutrons inelastic scattering cross section, have been performed on 56 Fe from 862 KeV to 3 MeV. The time of flight method has been used on the GELINA source of the IRMM in Geel (Belgium). Four barium fluoride scintillators, placed around the samples, recorded the gamma rays emissions coming from the iron and the boron. A study of the correlations between the partial elastic and inelastic lengths has been performed taking into account first transmission measures realized at Geel. (A.L.B.)

Amorphous-like interfacial layer between a high-T{sub c} superconducting Tl-1223 film and a Ag substrate examined by high-voltage high-resolution transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Kim, Bongjun; Kim, Hyuntak [Electronics and Tele-Communications Research Institute, Daejeon (Korea, Republic of); Nagai, Takuro; Matsui, Yoshio [National Institute for Materials Science, Tsukuba, Ibaraki (Japan); Horiuchi, Shigeo; Jeong, Daeyeong [Electrotechnology Research Institute, Changwon (Korea, Republic of); Deinhofer, Christian; Gritzner, Gerhard [Johannes Kepler University, Linz (Austria); Kim, Youngmin; Kim, Younjoong [Electron Microscopy Team, Korea Basic Science Institute, Daejeon (Korea, Republic of)

2006-05-15

The thin amorphous-like layer, formed at the interface between a high-T{sub c} superconducting (Tl{sub 0.5}, Pb{sub 0.5})(Sr{sub 0.8}, Ba{sub 0.2})Ca{sub 2}Cu{sub 3}O{sub y} (Tl-1223) film and a Ag substrate during heating at 910 .deg. C, has been examined by using high-voltage high-resolution transmission electron microscopy. The interfacial layer is less than 10 nm in thickness. It contacts the (001) plane of Tl-1223 and the (113) or (133) planes of Ag in most cases. Its composition is similar to that of Tl-1223, except for the inclusion of a substantial amount of Ag. Its formation proceeds by diffusion of Ag into Tl-1223, during which a structure change first occurs at the layer of CuO{sub 2} + Ca planes. The Tl(Pb)O + the Sr(Ba)O layers are then destroyed to cause the total structure to become amorphous-like. Furthermore, we have found that it is formed under an irradiation of highly energetic electrons.

High resolution STEM of quantum dots and quantum wires

DEFF Research Database (Denmark)

Kadkhodazadeh, Shima

2013-01-01

This article reviews the application of high resolution scanning transmission electron microscopy (STEM) to semiconductor quantum dots (QDs) and quantum wires (QWRs). Different imaging and analytical techniques in STEM are introduced and key examples of their application to QDs and QWRs...

Evaluation and optimization of the High Resolution Research Tomograph (HRRT)

International Nuclear Information System (INIS)

Knoess, C.

2004-01-01

Positron Emission Tomography (PET) is an imaging technique used in medicine to determine qualitative and quantitative metabolic parameters in vivo. The High Resolution Research Tomograph (HRRT) is a new high resolution tomograph that was designed for brain studies (312 mm transaxial field-of-view (FOV), 252 mm axial FOV). The detector blocks are arranged in a quadrant sharing design and consist of two crystal layers with dimensions of 2.1 mm x 2.1 mm x 7.5 mm. The main detector material is the newly developed scintillator lutetium oxyorthosilicate (LSO). Events from the different crystal layers are distinguished by Pulse Shape Discrimination (PSD) to gain Depth of Interaction (DOI) information. This will improve the spatial resolution, especially at the edges of the FOV. A prototype of the tomograph was installed at the Max-Planck Institute for Neurological Research in Cologne, Germany in 1999 and was evaluated with respect to spatial resolution, sensitivity, scatter fraction, and count rate behavior. These performance measurements showed that this prototype provided a spatial resolution of around 2.5 mm in a volume big enough to contain the human brain. A comparison with a single layer HRRT prototype showed a 10% worsening of the resolution, despite the fact that DOI was used. Without DOI, the resolution decreased considerably. The sensitivity, as measured with a 22 Na point source, was 46.5 cps/kBq for an energy window of 350-650 keV and 37.9 cps/kBq for an energy window of 400-650 keV, while the scatter fractions were 56% for 350-650 keV and 51% for 400-650 keV, respectively. A daily quality check was developed and implemented that uses the uniform, natural radioactive background of the scintillator material LSO. In 2001, the manufacturer decided to build a series of additional HRRT scanners to try to improve the design (detector electronics, transmission source design, and shielding against out-of-FOV activity) and to eliminate problems (difficult detector