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

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.

Intraocular Pressure–dependent Corneal Elasticity Measurement Using High-frequency Ultrasound

2019 ◽  
Vol 41 (5) ◽  
pp. 251-270 ◽  
Author(s):  
Laurentius O. Osapoetra ◽  
Dan M. Watson ◽  
Stephen A. McAleavey
Keyword(s):  
Intraocular Pressure ◽  
High Resolution ◽  
High Frequency ◽  
Wave Speed ◽  
Biomechanical Properties ◽  
Single Element ◽  
High Frequency Ultrasound ◽  
Spatially Resolved ◽  
Corneal Biomechanical Properties ◽  
Frequency Ultrasound

Measurement of corneal biomechanical properties can aid in predicting corneal responses to diseases and surgeries. For delineation of spatially resolved distribution of corneal elasticity, high-resolution elastography system is required. In this study, we demonstrate a high-resolution elastography system using high-frequency ultrasound for ex-vivo measurement of intraocular pressure (IOP)-dependent corneal wave speed. Tone bursts of 500 Hz vibrations were generated on the corneal surface using an electromagnetic shaker. A 35-MHz single-element transducer was used to track the resulting anti-symmetrical Lamb wave in the cornea. We acquired spatially resolved wave speed images of the cornea at IOPs of 7, 11, 15, 18, 22, and 29 mmHg. The IOP dependence of corneal wave speed is apparent from these images. Statistical analysis of measured wave speed as a function of IOP revealed a linear relation between wave speed and IOP cs = 0.37 + 0.22 × IOP, with the coefficient of determination R2 = 0.86. We also observed depth-dependent variations of wave speed in the cornea, decreasing from anterior toward posterior. This depth dependence is more pronounced at higher IOP values. This study demonstrates the potential of high-frequency ultrasound elastography in the characterization of spatially resolved corneal biomechanical properties.

scholarly journals Characterization of spatially resolved high resolution x-ray spectrometers for high energy density physics and light source experiments

2014 ◽  
Vol 85 (11) ◽  
pp. 11D612 ◽  
Author(s):  
K. W. Hill ◽  
M. Bitter ◽  
L. Delgado-Aparacio ◽  
P. Efthimion ◽  
N. A. Pablant ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Density ◽  
Light Source ◽  
High Energy ◽  
High Energy Density ◽  
X Ray ◽  
High Energy Density Physics ◽  
Spatially Resolved

scholarly journals Spatiotemporal evolution of a thin plasma foil with Kappa distribution

2014 ◽  
Vol 32 (4) ◽  
pp. 523-529 ◽  
Author(s):  
H. Mehdian ◽  
A. Kargarian ◽  
K. Hajisharifi
Keyword(s):  
Electron Distribution ◽  
Electron Distribution Function ◽  
High Energy ◽  
Spatiotemporal Evolution ◽  
Particle In Cell ◽  
High Energy Electrons ◽  
High Energy Tail ◽  
Kinetic Effects ◽  
The One ◽  
Thin Plasma

AbstractThe one-dimensional behavior of a thin plasma foil heated by laser is studied, emphasizing on the fully kinetic effects associated with initial energetic electrons using a relativistic kinetic 1D3V Particle-In-Cell code. For this purpose, the generalized Lorentzian (Kappa) function inclusive the high energy tail is employed for initial electron distribution. The presence of the initially high-energy electrons leads to a different ion energy spectrum than the initially Maxwellian distribution. It is shown for the smaller Kappa parameter k where the high energy tail of the electron distribution function becomes more significant, the electron cooling rate increases. Moreover, the spatiotemporal evolution of electric field is strongly affected by the initial super-thermal electrons.

Solitons and freak waves in a mixed nonextensive high energy-tail electron distribution

2014 ◽  
Vol 21 (6) ◽  
pp. 062101 ◽  
Author(s):  
Omar Bouzit ◽  
Leila Ait Gougam ◽  
Mouloud Tribeche
Keyword(s):  
Electron Distribution ◽  
High Energy ◽  
Freak Waves ◽  
High Energy Tail

scholarly journals Ghost imaging with electron microscopy inspired, non-orthogonal phase masks

2021 ◽  
Author(s):  
Akhil Kallepalli ◽  
Daan Stellinga ◽  
Ming-Jie Sun ◽  
Richard Bowman ◽  
Enzo Rotunno ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
High Energy ◽  
Reconstruction Method ◽  
Ghost Imaging ◽  
Light Modulator ◽  
Transmission Electron ◽  
Resolution Imaging ◽  
Electron Microscopes ◽  
Energy Processes

Abstract Transmission electron microscopes (TEM) achieve high resolution imaging by raster scanning a focused beam of electrons over the sample and measuring the transmission to form an image. While a TEM can achieve a much higher resolution than optical microscopes, they face challenges of damage to samples during the high energy processes involved. Here, we explore the possibility of applying computational ghost imaging techniques adapted from the optical regime to reduce the total, required illumination intensity. The technological lack of the equivalent high-resolution, optical spatial light modulator for electrons means that a different approach needs to be pursued. Using the optical equivalent, we show that a simple six-needle charged device to modulate the illuminating beam, alongside a novel reconstruction method to handle the resulting highly non-orthogonal patterns, is capable of producing images comparable in quality to a raster-scanned approach with much lower peak intensity.

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

2000 ◽  
Vol 88 (7) ◽  
Author(s):  
Jean Aupiais ◽  
N. Dacheux
Keyword(s):  
High Resolution ◽  
Liquid Scintillation ◽  
Gaussian Function ◽  
High Energy ◽  
Liquid Scintillation Spectrometer ◽  
Gaussian Shape ◽  
Peak Asymmetry ◽  
High Energy Tail

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

scholarly journals Influence of Electron-Electron Interaction on Electron Distributions in Short Si-MOSFETs Analysed Using the Local Iterative Monte Carlo Technique

VLSI Design ◽  
2001 ◽  
Vol 13 (1-4) ◽  
pp. 175-178
Author(s):  
T. Mietzner ◽  
J. Jakumeit ◽  
U. Ravaioli
Keyword(s):  
Monte Carlo ◽  
Electron Scattering ◽  
Electron Distribution ◽  
Field Effect Transistors ◽  
High Energy ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Electron Interaction ◽  
High Energy Tail ◽  
Electron Distributions

The effects of electron–electron interaction on the electron distribution in n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) are studied using the Local Iterative Monte Carlo (LIMO) technique. This work demonstrates that electron–electron scattering can be efficiently treated within this technique. The simulation results of a 90 nm Si-MOSFET are presented. We observe an increase of the high energy tail of the electron distribution at the transition from channel to drain.

Axial and radial development of the hot electron distribution in a helicon plasma source, measured by a retarding field energy analyzer (RFEA)

2022 ◽  
Author(s):  
Lisa Buschmann ◽  
Ashild Fredriksen
Keyword(s):  
Magnetic Field ◽  
Electron Distribution ◽  
Potential Drop ◽  
Plasma Source ◽  
High Energy ◽  
Plasma Potential ◽  
Field Configuration ◽  
Field Energy ◽  
Hot Electron ◽  
High Energy Tail

Abstract The information about the electron population of a helicon source plasma that expands along a magnetic nozzle is important for understanding the plasma acceleration across the potential drop that forms in the nozzle. The electrons need an energy higher than the potential drop to escape from the source. At these energies the signal of a Langmuir probe is less accurate. An inverted RFEA measures the high-energy tail of the electrons. To reach the probe, they must have energies above the plasma potential VP, which can vary over the region of the measurement. By constructing a full distribution by applying the electron temperature Te obtained from the electron IV-curve and the VP obtained from the ion collecting RFEA or an emissive probe, a density measure of the hot electron distribution independent of VP can be obtained. The variation of the high-energy tail of the EEDF in both radial and axial directions, in the two different cases of 1) a purely expanding magnetic field nozzle, and 2) a more constricted one by applying current in a third, downstream coil was investigated. The electron densities and temperatures from the source are then compared to two analytic models of the downstream development of the electron density. The first model considers the development for a pure Boltzmann distribution while the second model takes an additional magnetic field expansion into account. A good match between the measured densities and the second model was found for both configurations. The RFEA probe also allows for directional measurement of the electron current to the probe. This property is used to compare the densities from the downstream and upstream directions, showing a much lower contribution of downstream electrons into the source for a purely expanding magnetic field in comparison to the confined magnetic field configuration.

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