The Cosmic-Ray Counting Rate of a Single Geiger Counter from Ground Level to 161 Kilometers Altitude

The cosmic-ray counting rate of a single Geiger counter has been measured from ground level to an altitude of 161 kilometers. The equipment was carried in a V-2 rocket at geomagnetic latitude $\lambda =41\mathrm{}$ ° N. Especial care was taken to avoid multiplicative effects from surrounding material. A value of the charged primary cosmic-ray flux of $j=0.12\mathrm{}$/sec./${\mathrm{cm}}^2$/steradian, averaged over the upper hemisphere, is implied by the data above 55 km. This interpretation of the counting rate must be qualified by the as yet unknown contribution from secondaries which emerge from the atmosphere and execute orbits in the earth's magnetic field.