The isotope ${\mathrm{Ir}}^{196}$ has been reported to have a half-life of ∼9 days and to emit ${\beta }^{-}$ particles with a maximum energy of about 0.08 Mev. Using deuteron-bombarded enriched isotopes of platinum, it is shown that the previous mass assignment was incorrect. It is suggested that the ∼9-day activity found in deuteron bombardments of natural platinum is due to ${\mathrm{Ir}}^{189}$ and ${\mathrm{Ir}}^{190}$ produced by the ($d, n$) reaction on osmium impurities. An experimental upper limit of 5 hours for the ${\mathrm{Ir}}^{196}$ half-life can be set by these experiments. Rough cross sections for the ($d, \alpha$) reaction on ${\mathrm{Pt}}^{194}$ and ${\mathrm{Pt}}^{196}$ are given for several deuteron energies from 9.6 to 20.4 Mev.

• Received 8 December 1958

DOI:https://doi.org/10.1103/PhysRev.114.822