Internal Conversion Coefficients ofγRays inPu239

Abstract

The $K$-conversion coefficients of the predominantly $M1$ $\ensuremath{\gamma}$ rays of 209.7, 228.2, and 277.9 kev following the $\ensuremath{\beta}$ decay of ${\mathrm{Np}}^{239}$ have been measured using a curved crystal $\ensuremath{\gamma}$-ray spectrometer and a lens type $\ensuremath{\beta}$-ray spectrometer. The measured $K$-conversion coefficients are 1.76\ifmmode\pm\else\textpm\fi{}0.30, 1.60\ifmmode\pm\else\textpm\fi{}0.16, and 1.16\ifmmode\pm\else\textpm\fi{}0.12, respectively. A limit of less than 10% has been placed on the admixture of $E2$ in these radiations from a study of the $\frac{K}{L}$ and ${L}_{\mathrm{I}}:{L}_{\mathrm{II}}:{L}_{\mathrm{III}}$ conversion ratios. It is found, for $Z=94$, that the measured conversion coefficients show better agreement with the $M1$ predictions of Sliv who allowed for finite nuclear size than with Rose et al. who assumed a point charge nucleus. In addition, the $K$-conversion coefficients of the 254.7-, 285.5-, 316.2-, and 334.4-kev $\ensuremath{\gamma}$ rays of ${\mathrm{Pu}}^{23}$, have been measured to be 0.88\ifmmode\pm\else\textpm\fi{}0.32, 0.11\ifmmode\pm\else\textpm\fi{}0.02, 0.027\ifmmode\pm\else\textpm\fi{}0.005, and 0.025\ifmmode\pm\else\textpm\fi{}0.005, and the ${L}_{\mathrm{I}}$ and ${L}_{\mathrm{II}}$ conversion coefficients of the 106.4-kev $\ensuremath{\gamma}$ ray to be 0.062\ifmmode\pm\else\textpm\fi{}0.007 and 0.071\ifmmode\pm\else\textpm\fi{}0.007, respectively.