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Detailed Reference Information |
Millan, R.M., Lin, R.P., Smith, D.M., Lorentzen, K.R. and McCarthy, M.P. (2002). X-ray observations of MeV electron precipitation with a balloon-borne germanium spectrometer. Geophysical Research Letters 29: doi: 10.1029/2002GL015922. issn: 0094-8276. |
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The high-resolution germanium detector aboard the MAXIS (MeV Auroral X-ray Imaging and Spectroscopy) balloon payload detected nine X-ray bursts with significant flux extending above 0.5 MeV during an 18 day flight over Antarctica. These minutes-to-hours-long events are characterized by an extremely flat spectrum (~E-2) similar to the first MeV event discovered in 1996, indicating that the bulk of parent precipitating electrons is at relativistic energies. The MeV bursts were detected between magnetic latitudes 58¿--68¿ (L-values of 3.8--6.7) but only in the late afternoon/dusk sectors (14:30--00:00 MLT), suggesting scattering by EMIC (electromagnetic ion cyclotron) waves as a precipitation mechanism. We estimate the average flux of precipitating E ≥ 0.5 MeV electrons to be ~360 cm-2s-1, corresponding to about 5 ¿ 1025 such electrons precipitated during the eight days at L = 3.8--6.7, compared to ~2 ¿ 1025 trapped 0.5--3.6 MeV electrons estimated from dosimeter measurements on a GPS spacecraft. These observations show that MeV electron precipitation events are a primary loss mechanism for outer zone relativistic electrons. |
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Abstract |
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Keywords
Magnetospheric Physics, Energetic particles, precipitating, Magnetospheric Physics, Magnetosphere--inner, Magnetospheric Physics, Energetic particles, trapped |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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