Found 11 entries in the Bibliography.

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Variability of the Proton Radiation Belt

Significant steady but slow variability of radiation belt proton intensity, in the energy range \~19\textendash200 MeV and for L<2.4, has been observed in an empirical model derived from data taken by Van Allen Probes during 2013\textendash2019. It is compared to predictions of a theoretical model based on measured initial and boundary conditions. Two aspects of the variability are considered in detail and require adjustments to model parameters. Observed inward transport of proton intensity maxima near L=1.9 and associated ...

Selesnick, R.; Albert, J.;

YEAR: 2019     DOI: 10.1029/2019JA026754

protons; radial diffusion; Radiation belt; Van Allen Probes

Investigation of Solar Proton Access into the inner magnetosphere on 11 September 2017

In this study, access of solar energetic protons to the inner magnetosphere on 11 September 2017 is investigated by computing the reverse particle trajectories with the Dartmouth geomagnetic cutoff code [Kress et al., 2010]. The maximum and minimum cutoff rigidity at each point along the orbit of Van Allen Probe A is numerically computed by extending the code to calculate cutoff rigidity for particles coming from arbitrary direction. Pulse-height analyzed (PHA) data has the advantage of providing individual particle energies ...

Qin, Murong; Hudson, Mary; Kress, Brian; Selesnick, Richard; Engel, Miles; Li, Zhao; Shen, Xiaochen;

YEAR: 2019     DOI: 10.1029/2018JA026380

cutoff energy; cutoff location; Dartmouth geomagnetic cutoff code; Pulse height analyzed data; Solar proton; straggling function; Van Allen Probes


Modeling the Proton Radiation Belt With Van Allen Probes Relativistic Electron-Proton Telescope Data

An empirical model of the proton radiation belt is constructed from data taken during 2013\textendash2017 by the Relativistic Electron-Proton Telescopes on the Van Allen Probes satellites. The model intensity is a function of time, kinetic energy in the range 18\textendash600 MeV, equatorial pitch angle, and L shell of proton guiding centers. Data are selected, on the basis of energy deposits in each of the nine silicon detectors, to reduce background caused by hard proton energy spectra at low L. Instrument response functio ...

Selesnick, R.; Baker, D.; Kanekal, S.; Hoxie, V.; Li, X.;

YEAR: 2018     DOI: 10.1002/2017JA024661

data; protons; Radiation belt; Van Allen Probes


Comparison of Van Allen Probes radiation belt proton data with test particle simulation for the 17 March 2015 storm

The loss of protons in the outer part of the inner radiation belt (L = 2 to 3) during the 17 March 2015 geomagnetic storm was investigated using test particle simulations that follow full Lorentz trajectories with both magnetic and electric fields calculated from an empirical model. The simulation results presented here are compared with proton pitch angle measurements from the Van Allen Probe satellites Relativistic Electron Proton Telescope (REPT) instrument before and after the coronal mass ejection-shock-driven storm of ...

Engel, M.; Kress, B.; Hudson, M.; Selesnick, R.;

YEAR: 2016     DOI: 10.1002/2016JA023333

field line curvature scattering; inductive electric field; proton loss; Radiation belt; Van Allen Probes

Control of the innermost electron radiation belt by large-scale electric fields

Electron measurements from the Magnetic Electron Ion Spectrometer instruments on Van Allen Probes, for kinetic energies \~100 to 400 keV, show characteristic dynamical features of the innermost ( inline image) radiation belt: rapid injections, slow decay, and structured energy spectra. There are also periods of steady or slowly increasing intensity and of fast decay following injections. Local time asymmetry, with higher intensity near dawn, is interpreted as evidence for drift shell distortion by a convection electric field ...

Selesnick, R.; Su, Y.-J.; Blake, J.;

YEAR: 2016     DOI: 10.1002/2016JA022973

electric field; electrons; Inner radiation belt; Van Allen Probes

Formation of the inner electron radiation belt by enhanced large-scale electric fields

A two-dimensional bounce-averaged test particle code was developed to examine trapped electron trajectories during geomagnetic storms with the assumption of conservation of the first and second adiabatic invariants. The March 2013 storm was selected as an example because the geomagnetic activity Kp index sharply increased from 2 + to 7- at 6:00 UT on 17 March. Electron measurements with energies between 37 and 460 keV from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard Van Allen Probes (VAP) are used as i ...

Su, Yi-Jiun; Selesnick, Richard; Blake, J.;

YEAR: 2016     DOI: 10.1002/2016JA022881

DC electric fields; electron injections; Inner radiation belt; test particle simulation; Van Allen Probes; Van Allen Probes electron measurements

Inward diffusion and loss of radiation belt protons

Radiation belt protons in the kinetic energy range 24 to 76 MeV are being measured by the Relativistic Electron Proton Telescope on each of the two Van Allen Probes. Data have been processed for the purpose of studying variability in the trapped proton intensity during October 2013 to August 2015. For the lower energies (≲32 MeV), equatorial proton intensity near L = 2 showed a steady increase that is consistent with inward diffusion of trapped solar protons, as shown by positive radial gradients in phase space density at ...

Selesnick, R.; Baker, D.; Jaynes, A.; Li, X.; Kanekal, S.; Hudson, M.; Kress, B.;

YEAR: 2016     DOI: 10.1002/2015JA022154

protons; radial diffusion; Radiation belt; Van Allen Probes


Measurement of inner radiation belt electrons with kinetic energy above 1~MeV

Data from the Proton-Electron Telescope on the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, taken during 1992\textendash2009, are analyzed for evidence of inner radiation belt electrons with kinetic energy E > 1 MeV. It is found that most of the data from a detector combination with a nominal energy threshold of 1 MeV were, in fact, caused by a chance coincidence response to lower energy electrons or high-energy protons. In particular, there was no detection of inner belt or slot region electron ...

Selesnick, R.;

YEAR: 2015     DOI: 10.1002/2015JA021387

electrons; Inner zone; Radiation belt

High-energy radiation belt electrons from CRAND

A calculation of the inner radiation belt electron source from cosmic ray albedo neutron decay (CRAND) is described. High-energy electrons are included by Lorentz-transforming the β decay spectrum from the neutron rest frame to the Earth\textquoterights rest frame and combining with the known high-energy albedo neutron energy spectrum. Balancing the electron source with energy loss to atmospheric neutral atoms and plasma, and with a decay lifetime representative of plasma wave scattering, then provides an estimate of trappe ...

Selesnick, R.;

YEAR: 2015     DOI: 10.1002/2014JA020963

inner radiation; electron source from cosmic ray albedo neutron decay

Upper limit on the inner radiation belt MeV electron Intensity

No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (10s of MeV to GeV). The inner belt proton flux level, however, is relatively stable, thus for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a low Earth orbit, clearly demonstrate that there e ...

Li, X.; Selesnick, R.; Baker, D.; Jaynes, A.; Kanekal, S.; Schiller, Q.; Blum, L.; Fennell, J.; Blake, J.;

YEAR: 2015     DOI: 10.1002/2014JA020777

Van Allen Probes


Observations of the inner radiation belt: CRAND and trapped solar protons

Measurements of inner radiation belt protons have been made by the Van Allen Probes Relativistic Electron-Proton Telescopes as a function of kinetic energy (24 to 76 MeV), equatorial pitch angle, and magnetic L shell, during late-2013 and early-2014. A probabilistic data analysis method reduces background from contamination by higher energy protons. Resulting proton intensities are compared to predictions of a theoretical radiation belt model. Then trapped protons originating both from cosmic ray albedo neutron decay (CRAND) ...

Selesnick, R.; Baker, D.; Jaynes, A.; Li, X.; Kanekal, S.; Hudson, M.; Kress, B.;

YEAR: 2014     DOI: 10.1002/2014JA020188

Van Allen Probes