The flux of primary cosmic ray heavy nuclei has been measured with a sandwich of C.2 and G.5 emulsions near the coast of Georgia, magnetic latitude 42°N. The emulsions were exposed at about 122 000 ft for 7.5 hours and the calculated fluxes at the top of the atmosphere in particles/ m2-sec-sr were found to be:
Li, Be, B (L nuclei) 1.15.±0.3 C,N,O,F (M nuclei) 3.97±0.4 z≥10 (H nuclei) 1.29±0.3
This flight took place on May 25, 1960, near sun spot maximum. Evidence of solar modulation of the primary cosmic ray flux is shown.
Nelson, M. E.; Kerlee, D. D.; and Krienke, O. K. Jr. (1965) "Cosmic-ray Heavy Nuclei at Geomagnetic Latitude 42°N," Journal of the Institute for Research: Ser. A: No. 2, Article 2. Available at: http://digitalcommons.spu.edu/jir/vol3/iss2/2