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The Isotopic Composition of Hydrogen and Helium in Low Energy Cosmic Rays

Mewaldt, R. A. and Stone, E. C. and Vogt, R. E. (1975) The Isotopic Composition of Hydrogen and Helium in Low Energy Cosmic Rays. In: Proceedings of the 14th International Cosmic Rays Conference. Vol.1. Max Planck Gesellschaft , pp. 306-311.

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The Caltech Electron/Isotope Spectrometer on IMP-7 has been used to identify the isotopes ^2H and ^3He in low energy cosmic rays during solar quiet periods from October 1972 to October 1974. These observations cover the energy intervals 5 - 29 MeV/nuc for ^2H and 7 - 50 MeV/nuc for ^3He. The energy spectra of ^1H, ^2H and ^3He all fall rapidly with decreasing energy, giving ^2H/ ^1H and ^3He/ ^1H ratios essentially independent of energy as expected from adiabatic acceleration. The measured ^4He spectrum, however, was essentially flat over this energy interval, and therefore the ^2H/^4He ratio observed at 1 AU is not simply related to the interstellar abundances of these nuclei. However, comparisons of the ^2H/^1H and ^3He/^1H ratios with calculated spectra are possible.

Item Type:Book Section
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URLURL TypeDescription
Mewaldt, R. A.0000-0003-2178-9111
Stone, E. C.0000-0002-2010-5462
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Additional Information:This work was supported in part by NASA under contract NAS5-11066 and Grant NGR 05-002-160. G. J. Hurford made important contributions to a number of aspects of this work.
Group:Space Radiation Laboratory
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NASANGR 05-002-160
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Space Radiation Laboratory1975-04
Record Number:CaltechAUTHORS:20140410-103751097
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ID Code:44852
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Deposited On:14 Apr 2014 23:50
Last Modified:20 Feb 2020 14:33

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