  We have measured the isotopic abundances of neon and a number of other
species in the galactic cosmic rays (GCRs) using the Cosmic Ray Isotope
Spectrometer (CRIS) aboard the ACE spacecraft. Our data are compared to recent
results from two-component Wolf-Rayet (WR) models. The three largest deviations
of galactic cosmic ray isotope ratios from solar-system ratios predicted by
these models, 12C/16O, 22Ne/20Ne, and 58Fe/56Fe, are very close to those
observed. All of the isotopic ratios that we have measured are consistent with
a GCR source consisting of ~20% of WR material mixed with ~80% material with
solar-system composition. Since WR stars are evolutionary products of OB stars,
and most OB stars exist in OB associations that form superbubbles, the good
agreement of our data with WR models suggests that OB associations within
superbubbles are the likely source of at least a substantial fraction of GCRs.
In previous work it has been shown that the primary 59Ni (which decays only by
electron-capture) in GCRs has decayed, indicating a time interval between
nucleosynthesis and acceleration of >10^5 yr.In this paper we suggest a
scenario that should allow much of the 59Ni to decay in the OB association
environment and conclude that the hypothesis of the OB association origin of
cosmic rays appears to be viable.

Astrophysics