Cosmic ray investigation for the Voyager missions; energetic particle studies in the outer heliosphere — and beyond

Abstract

A cosmic-ray detector system (CRS) has been developed for the Voyager mission which will measure the energy spectrum of electrons from ≈3–110 MeV and the energy spectra and elemental composition of all cosmic-ray nuclei from hydrogen through iron over an energy range from ≈ 1–500 MeV/nuc. Isotopes of hydrogen through sulfur will be resolved from ≈ 2–75 MeV/nuc. Studies with CRS data will provide information on the energy content, origin and acceleration process, life history, and dynamics of cosmic rays in the galaxy, and contribute to an understanding of the nucleosynthesis of elements in the cosmic-ray sources. Particular emphasis will be placed on low-energy phenomena that are expected to exist in interstellar space and are known to be present in the outer Solar System. This investigation will also add to our understanding of the transport of cosmic rays, Jovian electrons, and low-energy interplanetary particles over an extended region of interplanetary space. A major contribution to these areas of study will be the measurement of three-dimensional streaming patterns of nuclei from H through Fe and electrons over an extended energy range, with a precision that will allow determination of anisotropies down to 1%. The required combination of charge resolution, reliability and redundance has been achieved with systems consisting entirely of solid-state charged-particle detectors.

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