Separation of carrier-free 185Os, 183Re and 184Re from irradiated tungsten targets

We have separated carrier-free osmium and rhenium chemical fractions from metallic tungsten targets irradiated with 65-MeV helium ions in the Berkeley 88-inch cyclotron. Gamma-ray spectral analyses showed only the presence of 185Os in the purified osmium fraction and only 183Re and 184Re (both isomers) in the rhenium fraction. The mass spectrum of a repurified 3-year-old osmium fraction showed no detectable levels of isotopically normal osmium but did yield a mass distribution of the light stable osmium isotopes produced in the irradiation. (orig.)