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Geomagnetically Trapped Anomalous Cosmic Rays

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. doi:10.1029/94JA03140.

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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
Related URLs:
URLURL TypeDescription
Cummings, A. C.0000-0002-3840-7696
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
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.
Group:Space Radiation Laboratory
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Space Radiation Laboratory1994-07
Issue or Number:A6
Record Number:CaltechAUTHORS:20140523-101203531
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45906
Deposited By: Deborah Miles
Deposited On:28 May 2014 19:11
Last Modified:10 Nov 2021 17:18

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