Lithium, Beryllium, and Boron in the Primary Cosmic Radiation

In order to resolve the controversy concerning the abundance of the light elements ($3<~Z<~5$) in the primary cosmic radiation, a further experiment has been performed. The charge spectrum of the cosmic radiation has been determined on October 19, 1957 in a stack of nuclear emulsions exposed nearer the top of the atmosphere than before. The results of the experiment prove that these light elements make up an appreciable fraction of all those nuclei with $Z>~3$ present in primary cosmic radiation. The flux values found after correction to the top of the atmosphere are, in particles/${\mathrm{m}}^2$ sec sterad: These values appear to be lower than observed previously in agreement with the decrease in the $\alpha$-nparticle flux associated with the sun's increased activity.