The Altitude Effect on the Specific Ionizing Power and Zenith Angle Distribution of Cosmic Rays

Measurements made with a quadruple-coincidence Geiger-Müller counting system at altitudes of 120 and 14,160 ft. give the intensity, J, of cosmic ray ionizing particles at various zenith angles, ψ. The distribution, J(ψ) = J0e−0.175ψ cos2ψ, does not differ significantly from any measured values, and agrees with all observations within 0.5 and 3.0% of the vertical intensities at the lower and higher altitudes respectively. The total number of rays incident per unit area per unit time was found, and the specific ionization was determined by comparison with ionization chamber measurements. The results are given below.Formula: see text† Ionization chamber data from Clay and Jongen (4).* Ionization chamber data from Millikan and Cameron (18).