Nuclei of oxygen to silicon in the solar flare of September 1, 1971

A stack of twentyfour cellulose triacetate plastic sheets was exposed to solar particles at 0758 hours U.T. on September 2, 1971 following a 2B solar flare. The payload was carried by a Nike-Apache sounding rocket fired from Fort Churchill, Canada. The flux and energy spectra of oxygen, neon, magnesium and silicon nuclei were measured in the energy interval of 3-20 MeV/amu. The ratios of Ne/O, Mg/O and Si/O were measured in 4-20 MeV/amu interval. These are compared with similar measurements made in India in the January 25, 1971 event. These results show that in 5-10 MeV/amu interval Ne/O ratio is enhanced only by approximately 50% as compared to its value at energy > 20 MeV/amu. Mg/O and Si/O ratios show enhancements by a factor of 4 to 5 at 5-10 MeV/amu as compared to the values of the ratios at high energies. The enhancements of the abundances at low energies for these nuclei are not an increasing function of the charge of the nucleus, but are dependent on the atomic properties of these nuclei. These features must be explained by any self-consistent theory of particle acceleration in sun. (author)