Source and loss processes of protons of the inner radiation belt

Farley, Thomas A.; Walt, M.

doi:10.1029/ja076i034p08223

Cited by 87 publications

(64 citation statements)

References 34 publications

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“…The CRAND source has been the subject of several theoretical calculations for comparison with the trapped proton data [e.g., Dragt, 1971;Farley and Walt, 1971;Jentsch and Wibberenz, 1980;Jentsch, 1981]. The secondary source has not been studied in detail, probably because of a lack of data on the composition of highenergy trapped ions.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric production of radiation belt light isotopes

Selesnick¹,

Mewaldt²

1996

J. Geophys. Res.

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Abstract. Nuclear interactions between inner zone protons and atoms in the upper atmosphere produce energetic H and He nuclei that are an additional radiation belt source. We calculate production rates of these isotopes from models of the inner zone proton intensity, the upper atmosphere drift-averaged composition and densities, and cross sections for the various interaction processes. For comparison with observations of radiation belt H and He isotopes, the production rates are combined with a model of the energy loss rate in the residual atmosphere to calculate particle intensities. Although the calculations are in principle straightforward, they depend on a detailed knowledge of the various model inputs, including models for radiation belt protons, and may also depend on the phase of the solar cycle. On the other hand, the results of the calculations, when compared with the observational data, can provide useful tests of the model inputs. Initial results show that the atmosphere is a significant source for inner zone 4 He, 3 He, and 2 H.

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Section: Introductionmentioning

confidence: 99%

Atmospheric production of radiation belt light isotopes

Selesnick¹,

Mewaldt²

1996

J. Geophys. Res.

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“…Radiation-belt protons [Farley et al, 1970] and electrons [Lanzerotti et al, 1970] in the 0.1-10 MeV energy range typically show a monotonic increase of phase-space density with L at fixed M and J (adiabatic invariants). This monotonicity suggests inward radial diffusion from an outer boundary at L 1 10 but does not prove that the particles maintaining the boundary condition originate outside the earth's magnetosphere.…”

Section: Itroduct Ion'mentioning

confidence: 99%

Earth's Radiation Belts.

Schulz¹

1984

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“…The dominant source for protons above ∼50 MeV in the inner belt is the decay of albedo neutrons from galactic cosmic ray protons that collide with nuclei in the atmosphere and ionosphere (Cosmic Ray Albedo Neutron Decay, or CRAND); e.g., Singer (1958);Freden and White (1962);Farley and Walt (1971). Free neutrons undergo beta decay with a mean lifetime of ∼885 seconds or ∼14.75 minutes (Paul 2009).…”

Section: Inner Belt Originsmentioning

confidence: 99%

“…Their use of polar ice proxies indicates a novel challenge for this theoretical treatment of the inner belt: an accurate specification of the current inner belt population must account for histories of the sources, losses, and the trapping field on timescales of hundreds of years or more (e.g. Farley and Walt 1971). The 2007 model predicts harder spectra (i.e.…”

Section: Inner Belt Proton Modelsmentioning

confidence: 99%

“…An early hypothesis held that the trapped radiation was related to the aurorae, while others found a natural link to albedo particles formed from nuclear interactions of galactic cosmic rays with the upper atmosphere (Singer 1958). The relevant facts to remember here are: the trapped inner belt proton environment saturated the Explorer-1 measurement in 1958 with high penetrating rates; and there was an early appreciation for the stability of the inner magnetosphere to form a strong magnetic bottle for natural and artificial injections of high-energy particles.The dominant source for protons above ∼50 MeV in the inner belt is the decay of albedo neutrons from galactic cosmic ray protons that collide with nuclei in the atmosphere and ionosphere (Cosmic Ray Albedo Neutron Decay, or CRAND); e.g., Singer (1958);Freden and White (1962);Farley and Walt (1971). Free neutrons undergo beta decay with a mean lifetime of ∼885 seconds or ∼14.75 minutes (Paul 2009).…”

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The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission

et al. 2012

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The Relativistic Proton Spectrometer (RPS) on the Radiation Belt Storm Probes spacecraft is a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from ∼60 MeV to ∼2000 MeV. RPS will investigate decadesold questions about the inner Van Allen belt proton environment: a nearby region of space that is relatively unexplored because of the hazards of spacecraft operation there and the difficulties in obtaining accurate proton measurements in an intense penetrating background. RPS is designed to provide the accuracy needed to answer questions about the sources and losses of the inner belt protons and to obtain the measurements required for the nextgeneration models of trapped protons in the magnetosphere. In addition to detailed information for individual protons, RPS features count rates at a 1-second timescale, internal radiation dosimetry, and information about electrostatic discharge events on the RBSP spacecraft that together will provide new information about space environmental hazards in the Earth's magnetosphere. Keywords Scientific GoalsWithin two Earth radii of the Earth's surface there is an unexplored region of trapped particles that are a challenge to accurately measure, a challenge to engineer for spacecraft design, and a challenge to understand given particle lifetimes that can exceed decades or even centuries. The inner Van Allen belt is a nearby reservoir of charged particles from a multitude of sources. We know the existence of trapped protons with energies beyond 1 GeV, secondary particles such as positrons, electrons, and light ions 4 He, 3 He, and 2 H, electrons that diffuse inward from the outer magnetosphere, and heavy ions that originate as interstellar neutral particles. These particles execute their gyration, bounce, and drift motions in a region with a relatively strong and stable magnetic field that shelters them from transients in the geomagnetic field, yielding the longest trapping lifetimes for particles in the Earth's magnetosphere. The tenuous upper atmosphere is both a source and sink of these populations, whose influence varies over the solar cycle and episodically during times of rapid atmospheric joule heating.The Relativistic Proton Spectrometer (RPS) 223Sorting out the various sources and losses in the Inner belt is challenging but there are particle characteristics that aid the process such as: extremely high proton energies that distinguish these particles as having a galactic cosmic ray origin; heavy ion composition that identifies these as being anomalous cosmic rays whose access to the inner belt is only afforded by their being mostly singly-ionized; and antimatter composition that identifies another branch the products of nuclear collisions between galactic cosmic rays and atmospheric atoms. For electrons the picture is less clear since there is little information about the electron energy spectrum and no identifiable characteristics of an electron that originates from a nuclear interaction versus one that diffu...

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Source and loss processes of protons of the inner radiation belt

Cited by 87 publications

References 34 publications

Atmospheric production of radiation belt light isotopes

Atmospheric production of radiation belt light isotopes

Earth's Radiation Belts.

The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission

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