Further Experiments on Cosmic-Ray Bursts

Abstract

The paper describes further results obtained by the observation of coincidences between pulses of a Geiger-Mueller counter tray and of an ionization chamber. The experiments were carried out partly aboard a B-29 aircraft and partly on the top of Mt. Evans in Colorado. The main purpose of the experiments at Mt. Evans was an investigation of the "transition curve" in lead. The experimental data are consistent with the assumption that the coincident bursts observed with a lead shield between the Geiger-Mueller tubes and the ionization chamber are mainly produced by cascade showers initiated by electrons and photons either incident upon the lead from the atmosphere or produced in the lead by nuclear interactions. The experiments aboard the B-29 furnish information on the variation with altitude of the radiation responsible for the nuclear interactions.