³He/4He ratios in the lower radiation belt as measured by trapped particles in a recovered satellite
Helium -3 has been found in the aluminum antenna housing from the recovered second stage of a pre-Apollo Saturn test flight launched January 28, 1964 and returned to earth on April 28, 1966. The amount of ³He found is about 6 × 10-10 cc (STP)/cm² with a 4He/³He ratio of 145 or less. The ³He is shown to come from the lower radiation belt as all other sources of ³He are orders of magnitude lower than the observed value. We suggest that there is a significant component of low energy flare particles in the radiation belts, although it is impossible to rule out other origins.