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Nuclear composition and energy spectra in the 1969 April 12 solar-particle event.Measurement of the charge composition for several of the multicharged nuclei and the energy spectra for hydrogen, helium, and medium (6 less than or equal to Z less than or equal to 9) nuclei in the Apr. 12, 1969, solar-particle event. The energy/nucleon spectral shape of the medium nuclei was again the same as that of the helium nuclei, and the ratio of these two species was consistent with the present best average of 58 plus or minus 5. By combining the results obtained here with previous work, improved estimates of the Ne/O and Mg/O values of 0.16 plus or minus 0.03 and 0.056 plus or minus 0.014, respectively, were obtained. Silicon and sulfur abundances relative to O were determined to be 0.208 plus or minus 0.008 plus or minus 0.006, respectively, and 85% confidence upper limits for Ar and Ca relative to O of 0.017 and 0.010 were obtained. Previously, these last four nuclei had only been listed as a group.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Bertsch, D. L.
Fichtel, C. E.
Reames, D. V. (NASA Goddard Space Flight Center Greenbelt, Md., United States)
Date Acquired
August 6, 2013
Publication Date
January 1, 1972
Publication Information
Publication: Astrophysical Journal
Volume: 171
Subject Category
Distribution Limits