Department of Physics and Mathematical Physics, The University of Adelaide
Abstract
We report preliminary results from the Joint Study of the Charge State of the
Anomalous Component, a cooperative project of the space agencies of the US and
the USSR. The so-called "anomalous" cosmic ray component, including the elements
He, N, 0, and Ne, as well as rarer species, is believed to represent a sample of neutral
interstellar atoms that has been swept into the heliosphere, singly ionized, and
then accelerated to energies as high as 60 MeV /nucleon. A key test of this theory is
a direct verification that these energetic nuclei are indeed singly ionized. This prediction
can be tested by comparing simultaneous measurements of the flux of
anomalous cosmic rays made inside and outside the magnetosphere, using the
geomagnetic field as a rigidity-dependent filter. Grigorov et al. have recently
reported measurements of the flux of 10 MeV /nucleon C, N, and 0 nuclei made during
1986 to 1988 by a series of KOSMOS satellites flown in low Earth orbit. We
have analyzed data from the same time periods from several instruments on IMP-8
and ICE, which were located outside the magnetosphere. We compare the 0 fluxes
inside and outside the magnetosphere over this time period and examine the implications
of these measurements for the charge state of anomalous cosmic rays
