LXXIX.<i>Nuclear transmutations produced by cosmic-ray particles of great energy</i>.-Part I. Observations with photographic plates exposed at an altitude of<i>11,000</i>feet

Abstract

Summary In this paper a phenomenological description is given of the results of observations made with “electron-sensitive” emulsions exposed at a height of 11,000 feet. It is shown that approximately half the nuclear disintegrations in which many charged particles are emitted are produced by particles of charge |e|, moving at relativistic velocities. The other half of these “stars” must be attributed to a neutral radiation. The directions of motion of most of the “primary” particles are inclined to the vertical at angles less than 40°. The particles appear to be able to pass through nuclei, imparting energy to the nucleons so that the nuclei evaporate, and having a 50 per cent probability of suffering a change of charge |e| in each encounter. If the energy of the incident particle is sufficiently great, “showers” of charged particles are produced. Photo-micrographs are given of characteristic examples of “stars” of different types.