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The Isotopic Composition of Solar Energetic Particles

Cohen, C. M. S. and Leske, R. A. and Christian, E. R. and Cummings, A. C. and Mewaldt, R. A. and Slocum, P. L. and Stone, E. C. and von Rosenvinge, T. T. and Wiedenbeck, M. E. (2000) The Isotopic Composition of Solar Energetic Particles. In: Acceleration and Transport of Energetic Particles Observed in the Heliosphere. AIP Conference Proceedings. No.528. American Institute of Physics , Melville, N.Y., pp. 55-62. ISBN 1-56396-951-3

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Since the launch of ACE in August 1997, the Solar Isotope Spectrometer (SIS) has observed 11 large solar particle events in which elemental and isotopic composition was determined over a large energy range. The composition of these events has raised many issues and challenged generally accepted characterizations of solar energetic particle (SEP) events. In particular, ^3He/^4He enhancements have been observed in several large events as well as enhancements of heavy ions typically associated with smaller impulsive events. The isotopic composition varies substantially from event to event (a factor of 3 for ^(22)Ne/^(20)Ne) with enhancements and depletions that are generally correlated with elemental composition. This correlation suggests that the isotopic enhancements may be related to the Q/M fractionation typically evident in the elemental composition of SEP events. However, there are also significant deviations from this pattern, which may imply that wave-particle resonances or other mass fractionation processes may be involved. We review the recent isotopic observations made with ACE and discuss their implications for particle acceleration and transport.

Item Type:Book Section
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Additional Information:© 2000 American Institute of Physics. Issue Date: 15 September 2000. This work was supported by NASA at the California Institute of Technology (under grant NAS5- 6912), the Jet Propulsion Laboratory, and the Goddard Space Flight Center. Climax neutron monitor data were obtained from the University of Chicago, National Science Foundation grant ATM-9613963.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Goddard Space Flight CenterUNSPECIFIED
Subject Keywords:solar cosmic ray particles, cosmic ray composition, isotope relative abundance, element relative abundance, cosmic ray propagation, transport processes, acceleration
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2000-18
Classification Code:PACS: 96.40.De; 96.50.Pw; 95.85.Ry
Record Number:CaltechAUTHORS:20111123-124917397
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Official Citation:The isotopic composition of solar energetic particles C. M. S. Cohen, R. A. Leske, E. R. Christian, A. C. Cummings, R. A. Mewaldt, P. L. Slocum, E. C. Stone, T. T. von Rosenvinge, and M. E. Wiedenbeck, AIP Conf. Proc. 528, 55 (2000), DOI:10.1063/1.1324281
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27952
Deposited By: Ruth Sustaita
Deposited On:23 Nov 2011 21:34
Last Modified:19 Feb 2015 19:35

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