The Determination of the Sign and the Energy Spectrum of Primary Cosmic Radiation

Abstract

An experiment is reported in this paper for the measurement of the complete azimuthal effect. This experiment was performed in Mexico City (geomagnetic latitude 29°, altitude 2242 m above sea level) for constant zenith angles 20°, 40°, and 60°. A characteristic feature is that the length of the atmospheric path is constant, hence the assumption is made that the number of secondaries detected by the cosmic-ray telescope is a measure of the number of primaries. The analysis yields an energy spectrum of the primary radiation of the form $\frac{K}{E^{1.45}}$ ($E$=energy, $K$=constant). There is no evidence of negative primary particles. The results are subject to revision because the penumbra bands at this latitude are only imperfectly known, and also because of the resolving power of our present apparatus. The possibility of a bright line spectrum, or of such a spectrum superimposed on a continuous distribution, is not ruled out. The possibility of negative primaries is excluded within the limits of experimental error. The spectrum obtained from our experimental data agrees completely with that determined from the experiment of Gill, carried out at Lahore, Punjab, India. The result is valid in the energy range from about 350 to 600 millistörmers, or 6 to 21 Bev if the primaries are protons.