THE ELEMENTAL COMPOSITION OF LOW-ALTITUDE 0.49MEV NUCLEON TRAPPED EQUATORIAL IONS/

Using instrumentation on board the SAMPEX satellite at similar to 600 km we present new measurements of the composition of a population of > 0.49 MeV/nucleon ions that are trapped near the geomagnetic equator. T hese ions gain access to the SAMPEX orbit as neutral particles via cha rge exchange collisions that continually occur within the higher altit ude radiation belt and contribute to the decay of storm-time enhanced ring current. At low altitudes a second charge exchange collision prod uces a trapped ion belt near the magnetic equator. This belt is epheme ral, as it is necessarily observed on drift paths that reach deep into the atmosphere near the South Atlantic Anomaly. We find the relative abundances of H:He:C:O:Ne-Fe are 7000 : 7.5 : 0.14 : 1.0 : 0.03. The l ow altitude particles are underabundant in Z>8 ions compared to the ra diation belt, possibly because the radiation belt Z>8 ions may not be stably trapped once they charge exchange to higher rigidities. We cann ot rule out the possible contribution of trapped anomalous cosmic rays to the heavy ions observed above 0.49 MeV/nucleon in this low altitud e population.