Composition of anomalous cosmic rays

The spectra of the anomalous component are some of the most unusual energetic particle spectra ever measured. The spectrum of each species is different, exhibiting a different energy for the peak in the differential spectrum, for example. If these particles are interstellar neutral atoms, ionized in the inner solar system and then swept out by the solar wind to be accelerated at the heliospheric boundary shock, as is widely believed, then each species is singly charged and one has a population of particles in which each species has a different rigidity at the same energy/nucleon. These particles thus may represent a unique laboratory for studying the acceleration of energetic particles and their transport through the heliosphere. To date 7 ions, H, He, C, N, O, Ne and Ar, all with high first ionization potentials have been observed. We will discuss the implications of the observed spectra and composition of this component.