TH-AB-201-05: Sensitivity of the Diagnostic Radiological Index of Protection (DRIP) to the Scatter Spectrum in Fluoroscopy

2015 ◽  
Vol 42 (6) ◽  
pp. 3718-3718
Author(s):  
A Pasciak ◽  
A Jones ◽  
L Wagner
Keyword(s):  
Scatter Spectrum

scholarly journals Particle precipitations during NEIAL events: simultaneous ground based observations at Svalbard

2007 ◽  
Vol 25 (6) ◽  
pp. 1323-1336 ◽  
Author(s):  
J. Lunde ◽  
B. Gustavsson ◽  
U. P. Løvhaug ◽  
D. A. Lorentzen ◽  
Y. Ogawa
Keyword(s):  
Minimum Energy ◽  
Soft Particle ◽  
Particle Precipitation ◽  
Characteristic Energy ◽  
Incoherent Scatter ◽  
Large Numbers ◽  
All Optical ◽  
Ion Acoustic ◽  
Scatter Spectrum ◽  
First Time

Abstract. In this paper we present Naturally Enhanced Ion Acoustic Lines (NEIALs) observed with the EISCAT Svalbard Radar (ESR). For the first time, long sequences of NEIALs are recorded, with more than 50 events within an hour, ranging from 6.4 to 140 s in duration. The events took place from ~08:45 to 10:00 UT, 22 January 2004. We combine ESR data with observations of optical aurora by a meridian scanning photometer at wavelengths 557.7, 630.0, 427.8, and 844.6 nm, as well as records from a magnetometer and an imaging riometer. The large numbers of observed NEIALs together with these additional observations, enable us to characterise the particle precipitation during the NEIAL events. We find that the intensities in all optical lines studied must be above a certain level for the NEIALs to appear. We also find that the soft particle precipitation is associated with the down-shifted shoulder in the incoherent scatter spectrum, and that harder precipitation may play a role in the enhancement of the up-shifted shoulder. The minimum energy flux during NEIAL events found in this study was ~3.5 mW/m2 and minimum characteristic energy around 50 eV.

Incoherent scatter spectrum of ionospheric plasma with an anisotropic temperature ion distribution

2012 ◽  
Vol 340 (2) ◽  
pp. 237-243 ◽  
Author(s):  
Bao-Ke Ma ◽  
Li-Xin Guo ◽  
Hong-Tao Su ◽  
Bei-Chen Zhang ◽  
Hong-Qiao Hu
Keyword(s):  
Ionospheric Plasma ◽  
Ion Distribution ◽  
Incoherent Scatter ◽  
Anisotropic Temperature ◽  
Scatter Spectrum

Observations of Plasma Line Splitting in the Ionospheric Incoherent Scatter Spectrum

2008 ◽  
Vol 100 (4) ◽  
Author(s):  
Asti N. Bhatt ◽  
Michael J. Nicolls ◽  
Michael P. Sulzer ◽  
Michael C. Kelley
Keyword(s):  
Incoherent Scatter ◽  
Line Splitting ◽  
Plasma Line ◽  
Scatter Spectrum

High frequency induced enhancements of the incoherent scatter spectrum at Arecibo

1972 ◽  
Vol 77 (7) ◽  
pp. 1242-1250 ◽  
Author(s):  
Herbert C. Carlson ◽  
William E. Gordon ◽  
Robert L. Showen
Keyword(s):  
High Frequency ◽  
Incoherent Scatter ◽  
Scatter Spectrum

Model Calculations on the Influence of Charged Mesospheric dust on the Incoherent Radar Spectrum

2020 ◽  
Author(s):  
Tinna Gunnarsdottir ◽  
Ingrid Mann ◽  
Wojciech Miloch
Keyword(s):  
Dust Particles ◽  
Radar Signal ◽  
Charged Dust ◽  
Large Set ◽  
Model Calculations ◽  
Radar Systems ◽  
Altitude Dependence ◽  
Dust Detection ◽  
Dust Component ◽  
Scatter Spectrum

<p>Detection of charged dust in the spectrum of incoherent radars has previously been proposed and examined to some degree. These dust particles are of nanometer size and reside at mesospheric altitudes due to incoming ablating meteors. They are difficult to detect and thus their influence on atmospheric processes is hard to determine. Theoretical studies suggest that charged nanometer sized dust in the mesosphere can be successfully detected in the radar spectrum. However, current radar systems like EISCAT are not capable to distinguish adequately the dust signal from the main signal because the influence is small. We expect however, that the upcoming new EISCAT_3D radar will improve the observation conditions. We here present model calculations to examine the influence of the charged dust component on the radar signal, a so-called dusty plasma effect. Instead of the previously assumed one size dust component, we simulate the incoherent scatter spectrum including a large set of dust size bins. We show that different sizes, number density and charge of dust influence the signal in different ways, either causing a narrowing or broadening of the spectrum. Here the results are presented in a systematic way and specific conditions identified that provide the largest chance of dust detection in the signal. A simple charging model is used to model the most probable charge and altitude dependence to simulate realistic dust distributions that are then used as input to the radar spectrum model. These results can then be used to compare with actual radar measurements. Off which the new EISCAT_3D radar system, ready in 2022, might provide the adequate resolution for these requirements.</p>

Detection of Mie Scattering Using a Resonance Fluorescence Monochromator

2002 ◽  
Vol 56 (9) ◽  
pp. 1237-1240 ◽  
Author(s):  
Dimitri Pappas ◽  
Tiffany L. Correll ◽  
Nathan C. Pixley ◽  
Benjamin W. Smith ◽  
J. D. Winefordner
Keyword(s):  
Spectral Resolution ◽  
Mie Scattering ◽  
Atomic Vapor ◽  
Resonance Fluorescence ◽  
Particulate Suspension ◽  
Instrument Response ◽  
Scatter Spectrum ◽  
Atomic Vapor Filters

The use of a resonance fluorescence monochromator (RFM) is described as a method for detecting Mie scatter. The detector has a spectral resolution limited by the atomic vapor used in the system (400 MHz for cesium). The RFM is used to detect Mie scatter from a particulate suspension, and deconvolution methods are used to extract the Mie scatter spectrum from the instrument response. The Mie scattering linewidth (140 MHz) is close to the literature value (100 MHz for air). Methods to reduce the linewidth of atomic vapor filters are briefly described.

scholarly journals Charged dust in the D-region incoherent scatter spectrum

2021 ◽  
Vol 87 (5) ◽  
Author(s):  
Tinna L. Gunnarsdottir ◽  
Ingrid Mann
Keyword(s):  
Electromagnetic Waves ◽  
Dust Particles ◽  
Charged Dust ◽  
Vhf Radar ◽  
Model Calculations ◽  
Incoherent Scatter ◽  
D Region ◽  
Dust Detection ◽  
Dust Component ◽  
Scatter Spectrum

We investigate the influence of charged dust on the incoherent scatter from the D-region ionosphere. Incoherent scatter is observed with high-power, large aperture radars and results from electromagnetic waves scattering at electrons that are coupled to other charged components through plasma oscillations. The influence of charged dust can hence be considered an effect of dusty plasma. The D-region contains meteoric smoke particles that are of nanometre size and form from incoming ablating meteors. Detection of such charged dust in the incoherent scatter spectrum from the D-region has previously been proposed and studied to some degree. We here present model calculations to investigate the influence of the charged dust component with a size distribution, instead of the one size dust components assumed in other works. The developed code to calculate the incoherent scatter spectrum from the D-region including dust particles with different sizes and different positive and negative charge states is made available (https://doi.org/10.18710/GHZIIY). We investigate how sizes, number density and charge state of the dust influence the spectrum during different ionospheric conditions. We consider the ionospheric parameters for the location of the EISCAT VHF radar during a year and find that conditions are most suitable for dust detection in winter below 80 km at times with increased electron densities. The prospects to derive dust parameters increase, when the incoherent scatter observations are combined with those of other instruments to provide independent information on electron density, neutral density and temperature.

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