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Maps of Hydrogen Isotopes at Low Altitudes in the Inner Zone from SAMPEX Observations

Looper, M. D. and Blake, J. B. and Mewaldt, R. A. (1998) Maps of Hydrogen Isotopes at Low Altitudes in the Inner Zone from SAMPEX Observations. Advances in Space Research, 21 (12). pp. 1679-1682. ISSN 0273-1177.

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The PET instrument aboard the SAMPEX satellite has provided us with long-term intra-calibrated observations of geomagnetically trapped protons and deuterons in the inner zone, suitable for use in constraining the low-altitude portions of radiation belt models being developed as successors to AP-8. These observations have been summarized elsewhere (Looper et al., 1996). Here we report a detection of geomagnetically-trapped tritium at energies from 14 to 35 MeV/nuc below L = 1.2, at about 1/8 the flux of deuterium previously reported at that location and at similar energy per nucleon. We also demonstrate the utility of the SAMPEX/PET observations for measuring the east-west anisotropy in the trapped particle flux at low altitudes, which is due to displacement of particle gyrocenters from the position of observation in a region of strong flux gradients. This anisotropy is implicitly ignored in omnidirectional radiation-flux models, but it can be important to mission planners considering how to distribute shielding over the surface of oriented spacecraft in low Earth orbit.

Item Type:Article
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Mewaldt, R. A.0000-0003-2178-9111
Additional Information:© 1998 COSPAR. Published by Elsevier Science Ltd. This work was supported by NASA at The Aerospace Corporation under NASA Cooperative Agreement 26979B and at Caltech under contract NAS5-30704 and grant NAGW-1919.
Group:Space Radiation Laboratory
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory1998-15
Issue or Number:12
Record Number:CaltechAUTHORS:20150108-142346717
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53383
Deposited By: Deborah Miles
Deposited On:09 Jan 2015 22:43
Last Modified:22 Nov 2019 09:58

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