LXXI. The abundance of lithium, beryllium, and boron in the primary cosmic radiation

Abstract

Summary In a previous paper, a method of determining the charge, of heavy nuclei in the cosmic radiation was described which depended on measuring the δ-ray density along a track in a photographic emulsion and the multiple scattering of the particle. The results suggested the presence of a large proportion of the light elements lithium, beryllium and boron in the radiation, a result in contradiction with that of other workers. The first part of the present paper describes a re-examination of the original method and evidence for its reliability. It is shown that an alternative method, based on observations of grain-density in the tracks of heavy particles recorded in less sensitive emulsions, gives results in agreement with those obtained by the δ-ray method. In the second part, the results of a more extended series of measurements by the, δ-ray method are described. The results indicate that at geo-magnetic latitude 55° N., the flux of lithium, beryllium and boron nuclei in the cosmic radiation is equal to, or larger than that of carbon, nitrogen and oxygen. Finally, the bearing of the results on the origin of the cosmic radiation is briefly discussed.