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Inferred Ionic Charge States for Solar Energetic Particle Events from 2012-2015 with ACE and STEREO

Labrador, A. W. and Sollitt, L. S. and Cohen, C. M. S. and Cummings, A. C. and Leske, R. A. and Mason, G. M. and Mewaldt, R. A. and Stone, E. C. and von Rosenvinge, T. T. and Wiedenbeck, M. E. (2015) Inferred Ionic Charge States for Solar Energetic Particle Events from 2012-2015 with ACE and STEREO. In: 34th International Cosmic Ray Conference (ICRC2015). Proceedings of Science. No.236. SISSA , Trieste, Italy, Art. No. 107.

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Mean ionic charge states for SEP events can reflect source temperatures, stripping during acceleration and transport, and the composition of source material. Multi-spacecraft measurements of mean ionic charge states for single SEP events can also demonstrate longitudinal dependence depending on seed particle composition or acceleration conditions. in previous studies, we calculated inferred high-energy ionic charge states for SEP events. The analysis method fits the energy dependence of decay times for each element in SEP events, combined with charge-to-mass ratios relative to a calibration element, and derives mean charge state estimates for elements from O to Fe. Previously, we applied the method using ACE and STEREO data to SEP events through the beginning of 2012, in order to elucidate evidence on seed populations or longitudinal variations with charge state for single SEP events, with varying results. In this paper, we continue applying the method to new SEP events from 2012 to 2015 in the ACE and STEREO data. With the three spacecraft widely spread apart during this time period, there are fewer single SEP events with multi-spacecraft data, but the wide spacing allows more SEP candidate events to be considered, separately, than would be available with just a single spacecraft. Our new results for two SEP events continue to be consistent with observed correlation between Q(Fe) and Fe/O in previous events.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Labrador, A. W.0000-0001-9178-5349
Cohen, C. M. S.0000-0002-0978-8127
Cummings, A. C.0000-0002-3840-7696
Leske, R. A.0000-0002-0156-2414
Mason, G. M.0000-0003-2169-9618
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:Creative Commons LicenseCopyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-ShareAlike. This work was supported by NASA grant NNX13A66G and NASA contract NA55-03131.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Series Name:Proceedings of Science
Issue or Number:236
Record Number:CaltechAUTHORS:20180828-122925213
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89236
Deposited By: George Porter
Deposited On:30 Aug 2018 14:35
Last Modified:16 Nov 2021 00:33

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