Cosmic-ray heavy nuclei at geomagnetic latitude 42° north

Abstract

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 feet for 7.5 hours, and the calculated fluxes at the top of the atmosphere in particles/m2-sec-ster were found to be: Li, Be, B, (L nuclei): 1.14±0.3; C, N, O, F, (M nuclei): 4.05±0.4; and Z≥10, (H nuclei): 1.32±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 by comparison with neutron monitor data.