Cerenkov scintillation counter measurements of the light, medium, and heavy nuclei in the primary cosmic radiation from sunspot minimum to sunspot maximum

The intensity and rigidity spectra of Be, B, C, N, and O have been measured on a series of three Skyhook balloon flights using a Cerenkov scintillation detector combination. The flights occurred at times close to solar minimum and maximum. The energy and charge resolution is comparable to that obtained by the latest emulsion techniques. It is observed that the light and medium nuclei display the same relative rigidity spectra throughout the solar cycle as the protons and α particles. This conclusion is valid only in the region studied (E>400 Mev/nucleon), and we may well expect striking variations for heavy primaries of low energy. The measured ratio of light to medium nuclei at the top of the atmosphere was 0.36±0.06; it was not observed to vary appreciably over the solar cycle.