  The ACE-CRIS collaboration has recently released the measurement of
radioactive $^{60}$Fe nuclei abundance in Galactic Cosmic Rays, in the energy
range $\sim 195-500$ MeV per nucleon. We model Cosmic Ray propagation and
derive from this measurement the $^{60}$Fe/$^{56}$Fe ratio that is expected in
the sources of Galactic Cosmic Rays. We describe Cosmic Ray origin and
transport within the framework of the disk/halo diffusion model, namely a
scenario in which the matter and the Cosmic Ray sources in our Galaxy are
confined to a thin disk, while Cosmic Ray propagation occurs in a much larger
halo with negligible matter density. We solve the Cosmic Ray transport equation
accounting for spallation reactions, decay and ionization losses as well as
advection. We find that the $^{60}$Fe/$^{56}$Fe ratio at the source must be
very close to the value detected in the local Cosmic Ray spectrum at Earth, due
to the fact that spallation reactions are more effective for $^{56}$Fe than for
$^{60}$Fe. Such a result could help identify the sources of Galactic Cosmic
Rays.
