The conversion coefficients of the 331- and 354-kev transitions in ${\mathrm{Pt}}^{196}$, following electron capture of ${\mathrm{Au}}^{196}$, were measured with the aid of a lens spectrometer adapted for coincidence measurements. The lower, 354-kev, gamma ray is an $E2\mathrm{}$ transition whereas the $K$-conversion coefficient of the 331-kev gamma ray was found to be 18±5% larger than that of a pure $E2\mathrm{}$ transition. From the good agreement of this excess with that expected for the 4.5% $M1\mathrm{}$ admixture derived from angular correlation measurements (18±2%), it is concluded that the fraction of conversion electrons due to an electric monopole transition is 0±5% (standard error). The intensity ratio of the two transitions is 0.278±0.010.

• Received 31 October 1955

DOI:https://doi.org/10.1103/PhysRev.101.1031