Shower Production by Penetrating Particles at 14,000 Feet

Abstract

Showers produced by penetrating particles were studied at 14,000 feet by simultaneous observations with G.M. counters, a cloud chamber, and an ionization chamber in a combined array. At least two-thirds of the observed showers generated by penetrating particles that struck a five-inch lead absorber consisted of a mixture of energetic electrons and particles heavier than electrons. The frequency of these events at high altitude relative to sea level shows that the initiating particles are not ordinary mesons. The presence of heavier particles in the electron shower indicates that the showers result from nuclear interactions in which the nucleus is disrupted rather than from a simple radiation process. Details of the events and their relation to some other cosmic-ray phenomena are discussed.