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An Update on Ultra-Heavy Elements in Solar Energetic Particles above 10 MeV/Nucleon

Leske, R. A. and Mewaldt, R. A. and Cohen, C. M. S. and Cummings, A. C. and Stone, E. C. and Wiedenbeck, M. E. and von Rosenvinge, T. T. (2007) An Update on Ultra-Heavy Elements in Solar Energetic Particles above 10 MeV/Nucleon. Space Science Reviews, 130 (1-4). pp. 335-340. ISSN 0038-6308. doi:10.1007/s11214-007-9191-5.

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Measurements below several MeV/nucleon from Wind/LEMT and ACE/ULEIS show that elements heavier than Zn (Z=30) can be enhanced by factors of ~100 to 1000, depending on species, in ^3He-rich solar energetic particle (SEP) events. Using the Solar Isotope Spectrometer (SIS) on ACE we find that even large SEP (LSEP) shock-accelerated events at energies from ~10 to >100 MeV/nucleon are often very iron rich and might contain admixtures of flare seed material. Studies of ultra-heavy (UH) SEPs (with Z>30) above 10 MeV/nucleon can be used to test models of acceleration and abundance enhancements in both LSEP and ^3He-rich events. We find that the long-term average composition for elements from Z=30 to 40 is similar to standard solar system values, but there is considerable event-to-event variability. Although most of the UH fluence arrives during LSEP events, UH abundances are relatively more enhanced in ^3He-rich events, with the (34<Z<40)/O ratio on average more than 50 times higher in ^3He-rich events than in LSEP events. At energies >10 MeV/nucleon, the most extreme event in terms of UH composition detected so far took place on 23 July 2004 and had a (34<Z<40)/O enhancement of ~250–300 times the standard solar value.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle ReadCube access
Leske, R. A.0000-0002-0156-2414
Mewaldt, R. A.0000-0003-2178-9111
Cohen, C. M. S.0000-0002-0978-8127
Cummings, A. C.0000-0002-3840-7696
Stone, E. C.0000-0002-2010-5462
Wiedenbeck, M. E.0000-0002-2825-3128
Additional Information:© 2007 Springer Science + Business Media B.V. Received: 2 February 2007. Accepted: 10 April 2007. Published online: 24 May 2007. This work was supported by NASA at the California Institute of Technology (grant NAG5-12929), the Jet Propulsion Laboratory, and the Goddard Space Flight Center.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Goddard Space Flight CenterUNSPECIFIED
Subject Keywords:Sun : abundances; Sun : particle emission; Sun : coronal mass ejections (CMEs); Sun : flares
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Other Numbering System NameOther Numbering System ID
Space Radiation Laboratory2007-16
Issue or Number:1-4
Record Number:CaltechAUTHORS:20100503-155507464
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:18119
Deposited By: Tony Diaz
Deposited On:05 May 2010 04:46
Last Modified:08 Nov 2021 23:41

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