Hydrogen, helium, and heavy nuclei from the solar event on November 15, 1960

Abstract

The flux and energy spectrums of solar hydrogen, helium, and heavy nuclei produced by the 3⁺ solar flare on November 15, 1960, have been measured in nuclear emulsions recovered from three rocket flights from Fort Churchill, Canada, at 42, 52, and 74 hours after the onset of the flare. The results are compared with similar measurements from two rocket flights during the November 12, 1960, solar cosmic-ray event and one during the September 3, 1960, event. It was found that the helium and medium nuclei had similar energy spectrums, steeper than those of protons in the energy interval from about 30 to 130 Mev/nucleon. The rigidity spectrums of hydrogen, helium, and medium nuclei were similar within experimental errors. The relative abundances of He, C, N, O and heavier nuclei were the same within the uncertainties each tune a measurement was made. The average ratio of the helium to medium nuclei is 60 ± 7. The composition of these nuclei is similar to that of the solar atmosphere but significantly different from that of the galactic cosmic rays. The time dependence of the ratios of the protons to helium nuclei and protons to medium nuclei is compared with the predictions of the models for the solar particle propagation of Parker and Gold. The experimental results are found to be consistent with a general diffusion model having strong scattering centers in the inner solar system and a boundary region consisting of progressively weaker scattering centers at large distances from the sun. The data can be interpreted as indicating that the diffusion coefficient is mainly velocity-dependent during the early part of the event, normally the first day or so, whereas at later times it is also a function of rigidity.