Radioactivities of Platinum and Iridium from Photonuclear Reactions in Platinum

Abstract

The products of photonuclear reactions induced in platinum by a 70-Mev synchrotron x-ray beam have been studied. No osmium activities were found. The iridium fraction included ${\mathrm{Ir}}^{192}$ and ${\mathrm{Ir}}^{194}$ and two new isotopes: a 140-min, 1-Mev ${\beta }^{-}$ emitter, probably ${\mathrm{Ir}}^{195}$, and a 7-min activity, probably ${\mathrm{Ir}}^{197}$. ${\mathrm{Pt}}^{193}$, ${\mathrm{Pt}}^{197}$, and the 88-min isotope which decays by isomeric transition were found in the platinum fraction. Some evidence is presented to question the assignment of the 88-min activity to ${\mathrm{Pt}}^{195}$. Relative yields of all these radioactive isotopes have been measured.