Evidence for existence of multiply charged argon ions in anomalous cosmic rays

The spectrum of Ar ions in anomalous cosmic rays in the energy range 14–42 MeV/nucleon was measured in the PLATAN-5 experiment at the Mir space station in 1994–1997. The spectrum is analyzed along with the data obtained by the SIS instrument on the ACE spacecraft in the circumterrestrial space. On the basis of the comparison of the spectra recorded within and beyond the magnetosphere, the average effective charge of ACR argon ions has been estimated. The estimate obtained is much larger than unity at energies exceeding 22 MeV/nucleon. The ion charge gradually increases with an increase in energy and reaches the value Q = 4 at an energy of 38 MeV/nucleon.