A Study of the Composition and Energy Spectra of Anomalous Cosmic Rays Using the Geomagnetic Field

We use instrumentation on SAMPEX and the Earth's field as a magnetic rigidity filter in a “double spectrometer” approach to measure the composition and energy spectra of anomalous cosmic rays (ACRs) with Z≥6. A “pure” sample of anomalous cosmic ray C, N, O, and Ne is obtained, with no significant evidence for other species. The bulk of ACRs are now known to be singly-charged, and the geomagnetic filter allows their energy spectra to be measured to higher energies than before. The anomalous oxygen spectrum is found to extend to at least ∼100 MeV/nuc, which has implications for models of the acceleration of these ions