Selesnick, R. S. and Cummings, A. C. and Cummings, J. R. and Mewaldt, R. A. and Stone, E. C. and von Rosenvinge, T. T.
(1994)
Geomagnetically Trapped Anomalous Cosmic Rays.
Journal of Geophysical Research A, 100
(A6).
p. 9503.
ISSN 0148-0227.
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Abstract
Since its launch in July 1992, the polar-orbiting satellite SAMPEX has been collecting data on geomagnetically trapped heavy ions, predominantly O, N, and Ne, at energies ≳ 15 MeV/nucleon and in a narrow L shell range near L = 2. Their location, elemental composition, energy spectra, pitch angle distribution, and time variations all support the theory that these particles originated as singly ionized interplanetary anomalous cosmic rays that were stripped of electrons in the Earth's upper atmosphere and subsequently trapped. The O are observed primarily at pitch angles outside the atmospheric loss cones, consistent with a trapped population, and their distribution there is nearly isotropic. The abundances relative to O of the N, possibly Ne, and especially C are lower than the corresponding interplanetary values, which may be indicative of the trapping efficiencies. The distributions of trapped N, O, and Ne in energy and L shell suggest that most of the ions observed at the SAMPEX altitude of ∼600 km are not fully stripped when initially trapped. A comparison of the trapped intensity with the much lower interplanetary intensity of anomalous cosmic rays provides model-dependent estimates of the product of the trapping probability and the average trapped particle lifetime against ionization losses in the residual atmosphere for particles that mirror near the SAMPEX altitude.
Item Type: | Article |
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Additional Information: | Copyright 1995 by the American Geophysical Union.
(Received May 26, 1994; revised November 28, 1994; accepted November 30, 1994.)
We thank J. B. Blake for helpful
discussions. This work was supported by NASA under
contract NAS5-30704 and grant NAGW-1919.
The editor thanks E. Möbius and another referee for their
assistance in evaluating this paper.
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Group: | Space Radiation Laboratory |
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Funders: | Funding Agency | Grant Number |
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NASA | NAS5-30704 | NASA | NAGW-1919 |
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Other Numbering System: | Other Numbering System Name | Other Numbering System ID |
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Space Radiation Laboratory | 1994-07 |
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Issue or Number: | A6 |
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Record Number: | CaltechAUTHORS:20140523-101203531 |
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Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20140523-101203531 |
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Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. |
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ID Code: | 45906 |
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Collection: | CaltechAUTHORS |
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Deposited By: |
Deborah Miles
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Deposited On: | 28 May 2014 19:11 |
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Last Modified: | 20 Feb 2020 14:33 |
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