Cosmic-Ray Bursts and the Nucleonic Cascade

The cosmic-ray burst rate has been measured as a function of altitude at geomagnetic latitudes of 0°, 29°, and 35°N by means of a thin-walled spherical ionization chamber. The burst rate at an atmospheric depth of 20 g/${\mathrm{cm}}^2$ increases by a factor of 6 between 0° and 52°. When the data are corrected for the effects of heavy primary nuclei, the residual rates, believed due almost entirely to nuclear disintegrations, show maxima below the top of the atmosphere. The maxima at 0°, 29°, 35°, and 52° occur at depths of approximately 100, 70, 60, and 50 g/${\mathrm{cm}}^2$ respectively.