The Variation with Altitude of the Production of Bursts of Cosmic-Ray Ionization

The rate of occurrence of bursts of ionization from 140 pounds of lead shot was measured in a fifty liter, Dowmetal ionization chamber, filled with nitrogen at 14.5 atmospheres pressure, at four elevations between sea level and the summit of Pike's Peak (4300 meters). The ionization chamber was so designed as to minimize the random fluctuations of the cosmic-ray ionization. The increase in the rate of occurrence with elevation was found to be very large, and increasingly greater at higher elevations. The rates of occurrence of all sizes of bursts greater than 1.5×${10}^6$ ions in the chamber increased with elevation in the same manner. The results are discussed in the light of W. F. G. Swann's theory.