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Propagation of Cosmic Rays Through Interstellar Space


Follin, James Wightman (1947) Propagation of Cosmic Rays Through Interstellar Space. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/1BMH-1K19.


The propagation of cosmic rays through interstellar space has been investigated with the view of determining what particles can traverse astronomical distances without serious loss of energy. The principal method of loss of energy of high energy particles is by interaction with radiation. It is found that high energy (1013-1018ev) electrons drop to one-tenth their energy in 108 light years in the radiation density in the galaxy and that protons are not significantly affected in this distance. The origin of the cosmic rays is not known so that various hypotheses as to their origin are examined. If the source is near a star it is found that the interaction of electrons and photons with the stellar radiation field and the interaction of electrons with the stellar magnetic field limit the amount of energy which these particles can carry away from the star. However, the interaction is not strong enough to affect the energy of protons or light nuclei appreciably. The chief uncertainty in the results is due to the possible existence of general galactic magnetic field. The main conclusion reached is that if there is a general galactic magnetic field, then the primary spectrum has very few photons, only low energy (˂ 1013 ev) electrons and the higher energy particles are primarily protons regardless of the source mechanism, and if there is no general galactic magnetic field, then the source of cosmic rays accelerates mainly protons and the present rate of production is much less than that in the past.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Physics and Mathematics
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Minor Option:Mathematics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Epstein, Paul Sophus
Thesis Committee:
  • Unknown, Unknown
Defense Date:1947
Record Number:CaltechTHESIS:06042015-144330294
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:8987
Deposited On:04 Jun 2015 22:27
Last Modified:17 Mar 2023 18:53

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