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New light on the nature and origin of the incoming cosmic rays

Bowen, I. S. and Millikan, R. A. and Neher, H. Victor (1938) New light on the nature and origin of the incoming cosmic rays. Physical Review, 53 (11). pp. 855-861. ISSN 0031-899X.

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Cosmic-ray electrons enter the atmosphere only in a definitely limited and relatively narrow energy range. The maximum of this energy distribution curve lies at about 6 billion e-volts. At 1 billion e-volts the curve has fallen to about a third of its maximum value, and on the other side of the maximum at some 17 billion e-volts the incoming energy also has about a third of its maximum value. The observed banded structure may possibly be partly due to the blocking effect of the sun's magnetic field on electrons trying to pass through it to the earth. The total cosmic-ray energy brought in by electrons of energy above 17 billion e-volts plus all that brought in by photons of all energies is about the same as the energy brought in by electrons alone of energies between 6 and 17 billion e-volts, and this energy is fully twice that brought in by all entering electrons of energies less than 6 billion e-volts. The smallness of the fraction of the total incoming energy that can be assigned to photons shows that the cosmic rays cannot ever have come through an appreciable amount of matter in comparison with an atmosphere before entering the solar system. The energies of the incoming rays correspond roughly to the annihilation energies of the atoms of the most abundant elements.

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Additional Information:©1938 The American Physical Society. Received 18 April 1938. We wish to express our very hearty appreciation of the assistance furnished by the U.S. Weather Bureau in supplying us with hydrogen at Omaha; by Professors E.L. Harrington, C.A. MacKay, and B.W. Currie, who assisted us in our flights at Saskatoon; and above all, to the Carnegie Corporation of New York for the funds with which these researches have been made possible under the general direction of the Carnegie Institution of Washington.
Issue or Number:11
Record Number:CaltechAUTHORS:BOWpr38a
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5476
Deposited By: Tony Diaz
Deposited On:20 Oct 2006
Last Modified:02 Oct 2019 23:23

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