Abstract
A primary cosmic ray particle energy specturm of Galactic origin with a sharp cut-off at an energy per nucleon of 3 × 104 GeV for protons and 5 × 104 GeV for heavier particles and extending only upto energies ∼ 1015 eV is deduced in part from the observed cosmic ray phenomena at the highest energies. It appears that the cut off is not due to the magnetic rigidity of the particles in the Galaxy but due to a cut off in or near the sources themselves. In particular, it is pointed out that Fermi type of acceleration is unlikely to be important in the production of energetic cosmic ray particles in the Galaxy. A pedestal in the energy spectrum from an extra Galactic component upto a maximum energy per nucleon ∼ 107 GeV with an upper limit of total energies ∼ 1018 eV has been added.
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The reason for limiting the primary cosmic ray spectrum to ∼1018 eV only is because evidence from air showers beyond this limit is not yet conclusive,see Subramanian, A., preprint T.I.F.R.-A.S.-1-72, April, 1972 (Current Science. 1972,41, 629).
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Communicated by Dr. B. V. Sreekantan,f.a.sc.
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Subramanian, A. A possible cosmic ray primary particle energy spectrum above 104 GeV and its astrophysical implications. Proc. Indian Acad. Sci. 76, 121–128 (1972). https://doi.org/10.1007/BF03049440
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DOI: https://doi.org/10.1007/BF03049440