Understanding the peak asymmetry in alpha liquid scintillation with β/γ discrimination

The peak evaluation in alpha liquid scintillation is known to be easy, mostly due to the gaussian shape of the peaks. However, we often observed a high-energy tail in addition to a pure gaussian function. This effect is only detectable with a high resolution α liquid scintillation spectrometer such as the PERALS

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High-resolution spectral imaging of SNR W44 and IC443 at 22 GHz with the Sardinia Radio Telescope

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317005221 ◽

2017 ◽

Vol 12 (S331) ◽

pp. 190-193

Author(s):

S. Loru ◽

A. Pellizzoni ◽

E. Egron ◽

N. Iacolina ◽

S. Righini ◽

...

Keyword(s):

High Resolution ◽

Radio Telescope ◽

High Frequency ◽

Electron Distribution ◽

Ad Hoc ◽

Imaging Techniques ◽

High Energy ◽

Spatially Resolved ◽

High Energy Tail ◽

Science Activities

AbstractIn the framework of the Astronomical Validation and Early Science activities of the Sardinia Radio Telescope (SRT, www.srt.inaf.it), we performed 22 GHz imaging observations of SNR W44 and IC443. Thanks to the single-dish imaging performances of SRT and innovative ad hoc imaging techniques, we obtained maps that provide a detailed view of the structure of the remnants. We are planning to exploit the high-frequency radio data of SNRs to better characterize the spatially-resolved spectra and search for possible spectral steepening or breaks in selected SNR regions, assessing the high-energy tail of the region-dependent electron distribution.

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High-resolution EM study of submicrometer-grained Al-Mg solid solution alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138993 ◽

1995 ◽

Vol 53 ◽

pp. 524-525

Author(s):

Z. Horita ◽

D. J. Smith ◽

M. Furukawa ◽

M. Nemoto ◽

R. Z. Valiev ◽

...

Keyword(s):

Electron Microscopy ◽

Solid Solution ◽

High Resolution ◽

Grain Boundaries ◽

Energy State ◽

High Energy ◽

Grain Structure ◽

Boundary Structure ◽

Solid Solution Alloy ◽

Average Grain Size

It is possible to produce metallic materials with submicrometer-grained (SMG) structures by imposing an intense plastic strain under quasi-hydrostatic pressure. Studies using conventional transmission electron microscopy (CTEM) showed that many grain boundaries in the SMG structures appeared diffuse in nature with poorly defined transition zones between individual grains. The implication of the CTEM observations is that the grain boundaries of the SMG structures are in a high energy state, having non-equilibrium character. It is anticipated that high-resolution electron microscopy (HREM) will serve to reveal a precise nature of the grain boundary structure in SMG materials. A recent study on nanocrystalline Ni and Ni3Al showed lattice distortion and dilatations in the vicinity of the grain boundaries. In this study, HREM observations are undertaken to examine the atomic structure of grain boundaries in an SMG Al-based Al-Mg alloy.An Al-3%Mg solid solution alloy was subjected to torsion straining to produce an equiaxed grain structure with an average grain size of ~0.09 μm.

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Ultra high resolution SEM at high voltage images individual fab fragments applied as molecular label to cell surface receptors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015232x ◽

1989 ◽

Vol 47 ◽

pp. 70-71

Author(s):

Klaus-Ruediger Peters

Keyword(s):

High Resolution ◽

High Energy ◽

Metal Coating ◽

Beam Diameter ◽

Surface Receptors ◽

Surface Mobility ◽

Metal Atoms ◽

Shadowing Effect ◽

Imaging Mode ◽

Deposition Techniques

Topographic ultra high resolution can now routinely be established on bulk samples in cold field emission scanning electron microscopy with a second generation of microscopes (FSEM) designed to provide 0.5 nm probe diameters. If such small probes are used for high magnification imaging, topographic contrast is so high that remarkably fine details can be imaged on 2DMSO/osmium-impregnated specimens at ribosome surfaces even without a metal coating. On TCH/osmium-impregnated specimens topographic resolution can be increased further if the SE-I imaging mode is applied. This requires that beam diameter and metal coating thickness be made smaller than the SE range of ~1 nm and background signal contributions be reduced. Subnanometer small probes can be obtained (only) at high accelerating voltages. Subnanometer thin continuous metal films can be produced under the following conditions: self-shadowing effect between metal atoms must be reduced through appropriate deposition techniques and surface mobility of metal atoms must be diminished through high energy sputtering and/or specimen cooling.

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Electromagnetic power of lightning superbolts from Earth to space

Nature Communications ◽

10.1038/s41467-021-23740-6 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

J.-F. Ripoll ◽

T. Farges ◽

D. M. Malaspina ◽

G. S. Cunningham ◽

E. H. Lay ◽

...

Keyword(s):

Low Frequency ◽

Optical Emission ◽

High Energy ◽

Very Low Frequency ◽

Electromagnetic Power ◽

Power Spectral ◽

High Energy Tail ◽

Van Allen Probes ◽

Long Time ◽

Low Frequency Waves

AbstractLightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

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Interaction Between Basal Stacking Faults and Prismatic Inversion Domain Boundaries in GaN

MRS Proceedings ◽

10.1557/proc-639-g3.44 ◽

2000 ◽

Vol 639 ◽

Cited By ~ 1

Author(s):

Philomela Komninou ◽

Joseph Kioseoglou ◽

Eirini Sarigiannidou ◽

George P. Dimitrakopulos ◽

Thomas Kehagias ◽

...

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Stacking Faults ◽

High Resolution Electron Microscopy ◽

High Energy ◽

Low Energy ◽

Inversion Domain ◽

Resolution Electron ◽

Domain Boundaries ◽

Inversion Domain Boundaries

ABSTRACTThe interaction of growth intrinsic stacking faults with inversion domain boundaries in GaN epitaxial layers is studied by high resolution electron microscopy. It is observed that stacking faults may mediate a structural transformation of inversion domain boundaries, from the low energy types, known as IDB boundaries, to the high energy ones, known as Holt-type boundaries. Such interactions may be attributed to the different growth rates of adjacent domains of inverse polarity.

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3-Dimensional Characterization of Polycrystalline Bulk Materials Using High-Energy Synchrotron Radiation

Materials Science Forum ◽

10.4028/www.scientific.net/msf.539-543.2353 ◽

2007 ◽

Vol 539-543 ◽

pp. 2353-2358 ◽

Cited By ~ 10

Author(s):

Ulrich Lienert ◽

Jonathan Almer ◽

Bo Jakobsen ◽

Wolfgang Pantleon ◽

Henning Friis Poulsen ◽

...

Keyword(s):

High Resolution ◽

Synchrotron Radiation ◽

High Energy ◽

Mapping Technique ◽

X Ray Diffraction ◽

Bulk Materials ◽

Reciprocal Space Mapping ◽

3 Dimensional ◽

Individual Grains

The implementation of 3-Dimensional X-Ray Diffraction (3DXRD) Microscopy at the Advanced Photon Source is described. The technique enables the non-destructive structural characterization of polycrystalline bulk materials and is therefore suitable for in situ studies during thermo-mechanical processing. High energy synchrotron radiation and area detectors are employed. First, a forward modeling approach for the reconstruction of grain boundaries from high resolution diffraction images is described. Second, a high resolution reciprocal space mapping technique of individual grains is presented.

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