A Cloud-Chamber Study of Nuclear Interactions in Lead and Aluminum. Part I

Abstract

The nuclear interactions of cosmic-ray particles in lead and aluminum have been studied in two cloud-chamber experiments. The results of the first experiment, which yields an unbiased sample of interactions of protons, are used to discuss the relative and absolute cross sections in the two materials and the absolute intensity and energy spectrum of the incident protons. The second experiment was designed to select interactions of neutrons in which at least one penetrating ionizing particle was produced. The types of interactions observed are in this case intimately related to the probability of triggering the cloud chamber. This problem is discussed in some detail, preparatory to more detailed analysis of this experiment in Part II of this paper.