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Atmospheric Ionization by Cosmic Radiation
Phys. Rev. 37, 1 – Published 1 January, 1931
DOI: https://doi.org/10.1103/PhysRev.37.1
Abstract
From Millikan's measurements of the intensity and the absorption coefficients of cosmic radiation the ionization in the atmosphere is calculated from sea level to 60 km. The electron density is negligibly small in this region. The ion density increases with the height to 3.5× ion pairs at about 50 km and is roughly constant above this to 60 or 70 km where the solar ultraviolet light ionization sets in. The 50 km ion bank refracts appreciably radio waves longer than 12 km and being unchanged with the day and night accounts for the propagation of waves longer than 12 km, which are known to show no marked diurnal variations. The agreement with the facts of long radio waves indicates that there exists in the high atmosphere but little cosmic radiation of less penetration than Millikan has already detected.
By considering the effect of the earth's magnetic field on high speed electrons the "run away" electron hypothesis of C. T. R. Wilson to account for cosmic radiation is shown to lead to a distribution most intense at low latitudes and feeble at high latitudes, thereby being in disagreement with Millikan's observation of the constancy of the cosmic radiation with latitude.
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