Radioactive Decays of Au194, Au196, and Au198

Abstract

The de-excitations of the 2+ second excited states of ${\mathrm{Pt}}^{194}$ and ${\mathrm{Pt}}^{196}$ have been studied to compare crossover transition intensities to the 0+ ground states relative to the known cascade transitions to the 2+ first excited states. An intermediate-image beta-ray spectrometer was used to measure the internal-conversion electron spectra occurring in the decays of ${\mathrm{Au}}^{194}$ and ${\mathrm{Au}}^{196}$. A conversion line is found in the decay of ${\mathrm{Au}}^{194}$ corresponding to a 0.618-Mev crossover having a transition intensity of 25% relative to the 0.290-Mev cascade, provided the latter is assumed to be $E2\mathrm{}$. In ${\mathrm{Pt}}^{196}$ an upper limit of 0.04% is placed on the intensity of a possible crossover transition compared with the 0.331-Mev cascade. ${\mathrm{Au}}^{194}$ exhibits the internal-conversion lines of 36 gamma-ray transitions which fit energetically into a proposed energy level scheme for ${\mathrm{Pt}}^{194}$. A search in the electron spectrum of ${\mathrm{Au}}^{198}$ showed no gamma-ray transitions other than the three already known.