The isotopic composition of hydrogen and helium in low energy cosmic raysThe Caltech Electron/Isotope Spectrometer on IMP-7 has been used to identify the isotopes H-2 and He-3 in low energy cosmic rays during solar quiet periods from October 1972 to October 1974. These observations cover the energy intervals 5 to 29 MeV/nuc for H-2 and 7 to 50 MeV/nuc for He-3. The energy spectra of H-1, H-2, and He-3 all fall rapidly with decreasing energy, giving H-2/H-1 and He-3/H-1 ratios essentially independent of energy as expected from adiabatic acceleration. The measured He-4 spectrum, however, was essentially flat over this energy interval, and therefore the H-2/He-4 ratio observed at 1 AU is not simply related to the interstellar abundances of these nuclei. However, comparisons of the H-2/H-1 and He-3/H-1 ratios with calculated spectra are possible.
Document ID
19760043900
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Mewaldt, R. A. (California Inst. of Tech. Pasadena, CA, United States)
Stone, E. C. (California Inst. of Tech. Pasadena, CA, United States)
Vogt, R. E. (California Institute of Technology Pasadena, Calif., United States)