scholarly journals Apolipoprotein E Expression and Behavioral Toxicity of High Charge, High Energy (HZE) Particle Radiation

2002 ◽  
Vol 43 (S) ◽  
pp. S219-S224 ◽  
Author(s):  
Yoshinori HIGUCHI ◽  
GREGORY A. NELSON ◽  
MARCELO VAZQUEZ ◽  
Daniel T. Laskowitz ◽  
JAMES M. SLATER ◽  
...  
Keyword(s):  
Apolipoprotein E ◽  
High Energy ◽  
Particle Radiation ◽  
High Charge ◽  
Behavioral Toxicity

scholarly journals The effects of the big storm events in the first half of 2015 on the radiation belts observed by EPT/PROBA-V

2016 ◽  
Vol 34 (1) ◽  
pp. 75-84 ◽  
Author(s):  
V. Pierrard ◽  
G. Lopez Rosson
Keyword(s):  
Charged Particle ◽  
High Resolution ◽  
Geomagnetic Storm ◽  
Energetic Particle ◽  
High Energy ◽  
Radiation Belts ◽  
Radiation Environment ◽  
Storm Event ◽  
Storm Events ◽  
Particle Radiation

Abstract. With the energetic particle telescope (EPT) performing with direct electron and proton discrimination on board the ESA satellite PROBA-V, we analyze the high-resolution measurements of the charged particle radiation environment at an altitude of 820 km for the year 2015. On 17 March 2015, a big geomagnetic storm event injected unusual fluxes up to low radial distances in the radiation belts. EPT electron measurements show a deep dropout at L > 4 starting during the main phase of the storm, associated to the penetration of high energy fluxes at L < 2 completely filling the slot region. After 10 days, the formation of a new slot around L = 2.8 for electrons of 500–600 keV separates the outer belt from the belt extending at other longitudes than the South Atlantic Anomaly. Two other major events appeared in January and June 2015, again with injections of electrons in the inner belt, contrary to what was observed in 2013 and 2014. These observations open many perspectives to better understand the source and loss mechanisms, and particularly concerning the formation of three belts.

scholarly journals Hubble Space Telescope observations of Europa in and out of eclipse

2010 ◽  
Vol 9 (4) ◽  
pp. 265-271 ◽  
Author(s):  
W.B. Sparks ◽  
M. McGrath ◽  
K. Hand ◽  
H.C. Ford ◽  
P. Geissler ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Broad Band ◽  
Line Emission ◽  
Optical Emission ◽  
High Energy ◽  
High Energy Particle ◽  
Wide Field ◽  
Particle Radiation ◽  
Space Telescope ◽  
Solar Blind

AbstractEuropa is a prime target for astrobiology and has been prioritized as the next target for a National Aeronautics and Space Administration flagship mission. It is important, therefore, that we advance our understanding of Europa, its ocean and physical environment as much as possible. Here, we describe observations of Europa obtained during its orbital eclipse by Jupiter using the Hubble Space Telescope. We obtained Advanced Camera for Surveys Solar Blind Channel far ultraviolet low-resolution spectra that show oxygen line emission both in and out of eclipse. We also used the Wide-Field and Planetary Camera-2 and searched for broad-band optical emission from fluorescence of the surface material, arising from the very high level of incident energetic particle radiation on ices and potentially organic substances. The high-energy particle radiation at the surface of Europa is extremely intense and is responsible for the production of a tenuous oxygen atmosphere and associated FUV line emission. Approximately 50% of the oxygen emission lasts at least a few hours into the eclipse. We discuss the detection limits of the optical emission, which allow us to estimate the fraction of incident energy reradiated at optical wavelengths, through electron-excited emission, Cherenkov radiation in the ice and fluorescent processes.

Simulating effects of the 774 AD solar proton event on atmospheric electricity

2021 ◽  
Author(s):  
Stergios Misios ◽  
Mads F. Knudsen ◽  
Christoffer Karoff
Keyword(s):  
Atmospheric Electricity ◽  
Circulation Model ◽  
High Energy ◽  
Solar Proton ◽  
Solar Proton Event ◽  
Proton Event ◽  
Atmospheric Conditions ◽  
Global Circulation Model ◽  
Fair Weather ◽  
Particle Radiation

&lt;p&gt;High energy cosmic rays of galactic and solar origin, natural radioactivity, lighting in thunderstorms and electrified shower clouds, produce ion clusters and charge the whole atmosphere causing a ubiquitous potential difference between the ionosphere and the surface. This Global Electric Circuit (GEC) allows the flow of charges to the surface in the fair-weather regions of the globe. Here, we simulate the effect of highly energetic particle radiation, in particular the 774 AD solar proton event, on the GEC with the aid of the global circulation model EMAC/MESSy. The simulations assume pre-industrial atmospheric conditions and the coupling of aerosol and atmospheric electricity schemes allows for ion-ion and ion-aerosol capture reactions. We discuss effects in fair weather current and atmospheric conductivity at different latitudinal bands. &lt;/p&gt;

scholarly journals Low Voltage High-Energy α-Particle Detectors by GaN-on-GaN Schottky Diodes with Record-High Charge Collection Efficiency

Sensors ◽  
2019 ◽  
Vol 19 (23) ◽  
pp. 5107 ◽  
Author(s):  
Sandupatla ◽  
Arulkumaran ◽  
Ranjan ◽  
Ing ◽  
Murmu ◽  
...  
Keyword(s):  
Low Voltage ◽  
Collection Efficiency ◽  
Schottky Diodes ◽  
High Energy ◽  
Charge Collection ◽  
Charge Carrier Density ◽  
Free Standing ◽  
Charge Collection Efficiency ◽  
High Charge ◽  
Drift Layer

A low voltage (–20 V) operating high-energy (5.48 MeV) α-particle detector with a high charge collection efficiency (CCE) of approximately 65% was observed from the compensated (7.7 × 1014 /cm3) metalorganic vapor phase epitaxy (MOVPE) grown 15 µm thick drift layer gallium nitride (GaN) Schottky diodes on free-standing n+-GaN substrate. The observed CCE was 30% higher than the bulk GaN (400 µm)-based Schottky barrier diodes (SBD) at –20 V. This is the first report of α–particle detection at 5.48 MeV with a high CCE at –20 V operation. In addition, the detectors also exhibited a three-times smaller variation in CCE (0.12 %/V) with a change in bias conditions from –120 V to –20 V. The dramatic reduction in CCE variation with voltage and improved CCE was a result of the reduced charge carrier density (CCD) due to the compensation by Mg in the grown drift layer (DL), which resulted in the increased depletion width (DW) of the fabricated GaN SBDs. The SBDs also reached a CCE of approximately 96.7% at –300 V.

Solar Particle Radiation Storms Forecasting and Analysis - The HESPERIA tools

2020 ◽  
Author(s):  
Olga Malandraki ◽  
Bernd Heber ◽  
Patrick Kuehl ◽  
Marlon Núñez ◽  
Arik Posner ◽  
...  
Keyword(s):  
Real Time ◽  
High Energy ◽  
Probability Of Detection ◽  
Proton Flux ◽  
Space Environment ◽  
National Observatory ◽  
Particle Radiation ◽  
Solar Particle Events ◽  
Horizon 2020 ◽  
Solar Particle

&lt;p&gt;Solar Energetic Particles (SEPs), ranging in energy from tens of keV to a few GeV, constitute an important con-tributor to the characterization of the space environment. SEP radiation storms may have durations from a period of hours to days or even weeks and have a large range of energy spectrum profiles. They pose a threat to mod-ern technology strongly relying on spacecraft and are a serious radiation hazard to humans in space, and are additionally of concern for avionics and commercial aviation in extreme cases. The High Energy Solar Particle Events forecasting and Analysis (HESPERIA) project, supported by the HORIZON 2020 programme of the Eu-ropean Union, has furthered our prediction capability of high-energy SEP events by developing new European capabilities for SEP forecasting and warning, while exploiting novel as well as already existing datasets. The HESPERIA UMASEP-500 tool makes real-time predictions of the occurrence of &gt;500 MeV and Ground Level Enhancement (GLE) events from the analysis of soft X-ray flux and high-energy differential proton flux measured by the GOES satellite network. Regarding the prediction of GLE events for the period 2000-2016, this tool had a Probability of Detection (POD) of 53.8% and a False Alarm Ratio (FAR) of 30.0%. For this period, the tool obtained an Advanced Warning Time (AWT) of 8 min taking as reference the alert time from the first NMstation; using the time of the warning issued by the GLE Alert Plus tool for the aforementioned period as reference, the tool obtained an AWT of 15 min (N&amp;#250;&amp;#241;ez et al. 2017). Based on the Relativistic Electron Alert System for Exploration (REleASE) forecasting scheme (Posner, 2007), the HESPERIA REleASE tools generate real-time predictions of the proton flux (30-50 MeV) at the Lagrangian point L1, making use of relativistic electrons (v&gt;0.9c) and near-relativistic (v&lt;0.8c) electron measurements provided by the SOHO/EPHIN and ACE/EPAM experiments, respectively. Analysis of historic data from 2009 to 2016 has shown the HESPERIA REleASE tools have a low FAR (&amp;#8764;30%) and a high POD (63%). Both HESPERIA tools are operational through the project&amp;#8217;s website (http://www.hesperia.astro.noa.gr) at the National Observatory of Athens and presented in the recently published book on 'Solar Particle Radiation Storms Forecasting and Analysis, The HESPERIA HORIZON 2020 Project and Beyond', edited by Malandraki and Crosby, Springer, Astrophysics and Space Sciences Library, 2018, freely available at https://www.springer.com/de/book/9783319600505. The HESPERIA tools have been selected as a top priority internationally by NASA/CCMC to be included in the simulations of the manned-mission to Mars by Johnson Space Center (ISEP project). The National Observatory of Athens participates in the ISEP project with a relevant contract.&lt;/p&gt;

scholarly journals Long-Term Sex- and Genotype-Specific Effects of 56Fe Irradiation on Wild-Type and APPswe/PS1dE9 Transgenic Mice

2021 ◽  
Vol 22 (24) ◽  
pp. 13305
Author(s):  
Maren K. Schroeder ◽  
Bin Liu ◽  
Robert G. Hinshaw ◽  
Mi-Ae Park ◽  
Shuyan Wang ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Radiation Effects ◽  
Motor Coordination ◽  
Space Radiation ◽  
High Energy ◽  
High Energy Particle ◽  
Wild Type ◽  
Particle Radiation ◽  
Specific Effects

Space radiation presents a substantial threat to travel beyond Earth. Relatively low doses of high-energy particle radiation cause physiological and behavioral impairments in rodents and may pose risks to human spaceflight. There is evidence that 56Fe irradiation, a significant component of space radiation, may be more harmful to males than to females and worsen Alzheimer’s disease pathology in genetically vulnerable models. Yet, research on the long-term, sex- and genotype-specific effects of 56Fe irradiation is lacking. Here, we irradiated 4-month-old male and female, wild-type and Alzheimer’s-like APP/PS1 mice with 0, 0.10, or 0.50 Gy of 56Fe ions (1GeV/u). Mice underwent microPET scans before and 7.5 months after irradiation, a battery of behavioral tests at 11 months of age and were sacrificed for pathological and biochemical analyses at 12 months of age. 56Fe irradiation worsened amyloid-beta (Aβ) pathology, gliosis, neuroinflammation and spatial memory, but improved motor coordination, in male transgenic mice and worsened fear memory in wild-type males. Although sham-irradiated female APP/PS1 mice had more cerebral Aβ and gliosis than sham-irradiated male transgenics, female mice of both genotypes were relatively spared from radiation effects 8 months later. These results provide evidence for sex-specific, long-term CNS effects of space radiation.

scholarly journals Parametric study of high-energy ring-shaped electron beams from a laser wakefield accelerator

2021 ◽  
Author(s):  
Antoine Maitrallain ◽  
Enrico Brunetti ◽  
Matthew Streeter ◽  
Brendan Kettle ◽  
Roman Spesyvtsev ◽  
...  
Keyword(s):  
Parametric Study ◽  
Electron Beams ◽  
High Energy ◽  
High Charge ◽  
Particle In Cell ◽  
Radiation Sources ◽  
Plasma Wakefield Accelerators ◽  
Laser Wakefield ◽  
Parametric Studies ◽  
Wakefield Accelerators

Abstract Laser wakefield accelerators commonly produce on-axis, low-divergence, high-energy electron beams. However, a high charge, annular shaped beam can be trapped outside the bubble and accelerated to high energies. Here we present a parametric study on the production of low-energy-spread, ultra-relativistic electron ring beams in a two-stage gas cell. Ring-shaped beams with energies higher than 750 MeV are observed simultaneously with on axis, continuously injected electrons. Often multiple ring shaped beams with different energies are produced and parametric studies to control the generation and properties of these structures were conducted. Particle tracking and particle-in-cell simulations are used to determine properties of these beams and investigate how they are formed and trapped outside the bubble by the wake produced by on-axis injected electrons. These unusual femtosecond duration, high-charge, high-energy, ring electron beams may find use in beam driven plasma wakefield accelerators and radiation sources.

Amorphization of Zr3Al by 1-MeV electron radiation

1988 ◽  
Vol 46 ◽  
pp. 464-465
Author(s):  
J. Koike ◽  
P.R. Okamoto ◽  
L.E. Rehn ◽  
M. Meshii
Keyword(s):  
Room Temperature ◽  
Ion Irradiation ◽  
National Laboratory ◽  
High Energy ◽  
High Energy Particle ◽  
Nominal Composition ◽  
Electron Radiation ◽  
Energy Particle ◽  
Particle Radiation ◽  
Lattice Softening

A crystalline to amorphous transition during high energy particle radiation has been reported in various intermetallic compounds. Chemical disordering is known to precede amorphization, which takes place only below a certain temperature. In Zr3A1, chemical disordering has been observed during 1-MeV electron radiation at temperatures between 130 and 375K but no amorphization has been reported. A large decrease in shear modulus was also observed during chemical disordering of Zr3Al by 1-MeV Kr ion irradiation at room temperature, followed by amorphization. In the present work, the possibility of amorphization of Zr3Al by electron radiation was examined, and the lattice softening due to chemical disordering was studied with electron diffraction.An alloy with a nominal composition of Zr-25at%Al was furnished by Chalk River National Laboratory. It was annealed at 925°C for 2 weeks and subsequently sliced and jet-polished. Specimen was irradiated and examined at 52K with 1-MeV electrons in the Argonne-HVEM.

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