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Time Variations of Solar Energetic Particle Abundances Observed by the ACE Spacecraft

von Rosenvinge, T. T. and Cohen, C. M. S. and Christian, E. R. and Cummings, A. C. and Leske, R. A. and Mewaldt, R. A. and Slocum, P. L. and Stone, E. C. and Wiedenbeck, M. E. (1999) Time Variations of Solar Energetic Particle Abundances Observed by the ACE Spacecraft. In: Proceedings of the 26th International Cosmic Ray Conference. International Union of Pure and Applied Physics , pp. 1999-2004.

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The abundances of elements from Helium to Iron have been observed in nine different solar energetic particle (SEP) events using the Solar Isotope Spectrometer (SIS) on-board the Advanced Composition Explorer (ACE). SIS has a large geometry factor (~38 cm^2-sr), enabling us to observe abundances on a time scale of hours. In this paper we repo1t on substantial temporal variations of the observed abundances within events and from event to event. We wish to understand these results in terms of acceleration and transpo1t processes, taking into account factors such as first ionization potential, particle charge states, spectral shape, and event type (gradual and impulsive). It is essential that these variations be understood if we are to reliably estimate the composition of the sun from direct observations of SEP abundances.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Cohen, C. M. S.0000-0002-0978-8127
Christian, E. R.0000-0003-2134-3937
Cummings, A. C.0000-0002-3840-7696
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:© University of Utah. Provided by the NASA Astrophysics Data System. TvR thanks Donald Reames and Allan Tylka for instructive discussions on this topic. This work was supported by NASA at the California Institute of Technology (under grant NAG5-6912), the Jet Propulsion Laboratory, and the Goddard Space Flight Center.
Group:Space Radiation Laboratory
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Space Radiation Laboratory1999-13
Record Number:CaltechAUTHORS:20150211-142207624
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54739
Deposited By: Deborah Miles
Deposited On:13 Feb 2015 15:16
Last Modified:09 Mar 2020 13:19

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