Measurements of the cosmic-ray;(p) over bar/p ratio are compared with predi
ctions from an inhomogeneous disk-diffusion model of (p) over bar productio
n and propagation within the Galaxy, combined with a calculation of the mod
ulation of the interstellar cosmic-ray spectra as the particles propagate t
hrough the heliosphere to the Earth. The predictions agree with the observe
d (p) over bar/p spectrum. Adding a finite p lifetime to the model, we obta
in the limit tau((p) over bar) > 0.8 Myr (90% CL).