Change of solar flare proton to alpha ratios during an energetic storm particle event

Observations of the temporal behavior of energetic storm protons and alpha particles are presented for the event associated with the storm sudden commencement observed on Earth on March 8, 1970. The data are obtained on board the low altitude polar orbiting satellite GRS-A/AZUR by means of two particle telescopes. Large changes in the proton to alpha ratios for particles of equal energy and for particles of equal energy per nucleon are observed, whereas no significant change in the equal energy per charge ratio is observed. Electric fields, Fermi acceleration and cyclotron resonance are discussed as possible modulation mechanisms.