A STUDY OF THE HYDROGEN,HELIUM, AND HEAVY NUCLEI IN THE NOVEMBER12, 1960, SOLAR COSMIC RAY EVENT by

The composition and energy spectra of solar cosmic rays from the No-vember 12, 1960, solar flare were studied by using rocket-borne nuclear emulsions. The abundances of hydrogen, helium, carbon, nitrogen, oxygen, neon, and larger nuclei were determined; and upper limits were set for light nuclei (3 5Z <5) and fluorine nuclei. The relative numbers of helium, light, medium (6-<Z 5 9), and large (Z < 10) nuclei in the solar beam were found to be 680 * 110, <0.1, 10, and 1.0 + 0.3 respectively. The composition was similar to that of the solar atmosphere, as determined by spectroscopic means, for those elements where a comparison could be made but was markedly different from that of galactic cosmic rays. The differential energy per nucleon spectra of hydrogen, helium, and medi-um nuclei could be represented by an equation of the form dJ/dW = K(W/Wo)-7 for kinetic energies greater than 35 Mev/nucleon. The values of 7 ' for helium and medium nuclei were the same within uncertainties, but larger than that for hydrogen nuclei by a factor of more than 2 in the energy interval from 4