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| Titel |
Transforming in-situ observations of CME-driven shock accelerated protons into the shock's reference frame. |
| VerfasserIn |
I. M. Robinson, G. M. Simnett |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 23, no. 5 ; Nr. 23, no. 5 (2005-07-28), S.1931-1941 |
| Datensatznummer |
250015277
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| Publikation (Nr.) |
 copernicus.org/angeo-23-1931-2005.pdf |
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| Zusammenfassung |
| We examine the solar energetic particle event following solar activity from 14, 15 April 2001
which includes a "bump-on-the-tail" in the proton energy spectra at 0.99 AU from the Sun. We
find this population was generated by a CME-driven shock which arrived at 0.99 AU around
midnight 18 April. As such this population represents
an excellent opportunity to study in isolation, the effects of proton acceleration by the
shock. The peak energy of the bump-on-the-tail evolves to progressively lower energies as the
shock approaches the observing spacecraft at the inner Lagrange point.
Focusing on the evolution of this peak energy
we demonstrate a technique which transforms these in-situ spectral observations
into a frame of reference co-moving with the shock whilst making allowance for the effects of pitch angle
scattering and focusing. The results of this transform suggest the bump-on-the-tail population was not driven
by the 15 April activity but was generated or at least modulated by a CME-driven shock which left the Sun on
14 April. The existence of a bump-on-the-tail population is predicted by models in Rice et al. (2003) and Li et al. (2003) which we compare with observations and the results of our analysis
in the context of both the 14 April and 15 April CMEs. We find an origin of the bump-on-the-tail
at the 14 April CME-driven shock provides better agreement with these modelled predictions although
some discrepancy exists as to the shock's ability to accelerate 100 MeV protons.
Keywords. Solar physics, astrophysics and astronomy (Energetic
particles; Flares and mass ejections) – Space plasma
physics (Transport processes) |
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