High-Altitude Intensities of the Medium and Heavy Cosmic-Ray Nuclei and of the Star-Producing Component over a 25-Hour Interval

Results are reported on a study of the hourly averaged values of intensity of medium and heavy cosmic-ray nuclei and of the star-producing component over a day and night interval, at an average atmospheric depth of 15 g/${\mathrm{cm}}^2$. The equipment was carried aloft by a Skyhook balloon on August 6, 1954 from Minneapolis, Minnesota (geomagnetic latitude 55°N). A large, thin-walled spherical pulse-ionization chamber served as the detecting instrument. Approximately 125 000 of these cosmic-ray events were recorded over the 25-hour flight interval; thus, statistical counting rate fluctuations were reduced substantially below those previously attained in this field. Analysis shows that approximately one-half of the counting rate at 15 g/${\mathrm{cm}}^2$ can be ascribed to the medium and heavy nuclei, the remainder being reasonably accounted for as arising from the star-producing component.