Heavy Nuclei in the Primary Cosmic Radiation at Prince Albert, Canada. I. Carbon, Nitrogen, and Oxygen

Abstract
A stack of G-5 emulsion, exposed at 120 000 feet for 8 hours at 61°N has been used to study the charge and energy spectrum of heavy nuclei at the low-energy end. Energy measurements have been made on C, N, and O nuclei up to 1 Bev/nucleon. The spectrum shows a broad maximum at 550 Mev/nucleon, extrapolated to the top of the atmosphere. Various possibilities to explain this spectrum are discussed. However, it seems desirable to determine the energy spectrum of the other heavy-nuclei components in this energy region in order to gain a more complete understanding of the whole problem. Measurements of this kind are in progress and will be reported.