Composition and energy spectra of heavy nuclei with 0.5 < E < 40 MeV per nucleon in the January 24, and September 1, 1971 solar flares

Energy spectra of 0, Si, and Fe between 0.5 and 40 MeV per nucleon have been measured with stacks of plastic detectors exposed in a rocket during the 1971 January 24 flare. The Fe/Si ratio decreases from 1.8 + 0.3 to 0.42 1 0.14 with energy. In both the January 24 flare and the September 1 flare, the abundances of elements 10 < Z < 28 at 15 MeV per nucleon are similar to high-energy cosmic-ray source abundances; S, Ne, and Ar are significantly lower than current solar values.