Cosmic-ray flux variation with height in the atmosphere

Abstract

Analysis of emulsions exposed to cosmic radiation at atmospheric depths between 10 and 40 g/cm2 at λ = 47 °S geomagnetic on 11 December 1964 shows that there is little variation with altitude in proton flux in this altitude range. However, the total star production rate increases with increasing atmospheric depth but with a smaller slope than that measured by Geiger counter. Preliminary results obtained from exposures made in November 1965 at 8.5, 28.4, and 58 g/cm2 show that the values of proton flux at 8.5 and 58 g/cm2 are lower than that at 28.4 g/cm2. A study of the rate of production of stars at λ = 43° S and 9 g/cm2 over the period April 1962 to September 1966 shows some correlation with the ground-based neutron monitor count rate. The proton flux at the top of the atmosphere at latitude 47° S is estimated as 900 ± 100 protons/m2 sr s.