Mewaldt, R. A. and Mason, G. M. and Cohen, C. M. S. (2012) The dependence of solar energetic particle fluences on suprathermal seed-particle densities. In: Space weather : the space radiation environment. AIP Conference Proceedings. No.1500. American Institute of Physics , Melville, NY, pp. 128-133. ISBN 978-0-7354-1114-2. https://resolver.caltech.edu/CaltechAUTHORS:20130114-101755528
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Abstract
Measurements during solar cycle 23 showed that most solar energetic particles (SEPs) are accelerated from a seed-population of suprathermal ions (e.g., >10 keV/nuc) rather than from the bulk solar wind. In this case the SEP fluence should depend on the pre-existing density of suprathermal ions. Lacking near-Sun measurements of suprathermal ion densities we have used ACE/ULEIS daily-average densities of suprathermal Fe at 1 AU during 1998-2005 as a proxy. We find that the maximum Fe daily-average SEP fluences measured by ACE/SIS are apparently limited by the pre-existing suprathermal number density. Similarly, large fluences of Fe in solar energetic particle events only occurred when there was a pre-existing high density of suprathermal Fe. We conclude that in situ suprathermal ion data can play a key role in estimating the probability of large SEP events, or in forecasting all-clear periods.
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| Additional Information: | © 2012 American Institute of Physics. NASA funded this work under grants NNX08AI11G and NNX11A075G at Caltech, and NNX10AT75G at JHU/APL; and subcontracts SA2715-26309 and SA4889-26309 from UC Berkeley under NASA contract NAS5-03131. We are grateful for the availability of SWEPAM data from the ACE Science Center. | ||||||||||||||
| Group: | Space Radiation Laboratory | ||||||||||||||
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| Subject Keywords: | cosmic ray propagation; iron; solar wind | ||||||||||||||
| Series Name: | AIP Conference Proceedings | ||||||||||||||
| Issue or Number: | 1500 | ||||||||||||||
| Classification Code: | PACS: 96.30.Ys; 96.50.Vg; 96.60.Q-; 96.60.Vg | ||||||||||||||
| DOI: | 10.1063/1.4768755 | ||||||||||||||
| Record Number: | CaltechAUTHORS:20130114-101755528 | ||||||||||||||
| Persistent URL: | https://resolver.caltech.edu/CaltechAUTHORS:20130114-101755528 | ||||||||||||||
| Official Citation: | The dependence of solar energetic particle fluences on suprathermal seed-particle densities R. A. Mewaldt, G. M. Mason, and C. M. S. Cohen, AIP Conf. Proc. 1500, 128 (2012), DOI:10.1063/1.4768755 | ||||||||||||||
| Usage Policy: | No commercial reproduction, distribution, display or performance rights in this work are provided. | ||||||||||||||
| ID Code: | 36347 | ||||||||||||||
| Collection: | CaltechAUTHORS | ||||||||||||||
| Deposited By: | INVALID USER | ||||||||||||||
| Deposited On: | 14 Jan 2013 21:51 | ||||||||||||||
| Last Modified: | 09 Nov 2021 23:21 |
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