The $\beta$ decay of ${\mathrm{Ru}}^{103}$ (39.6 d) has been investigated with an iron-core, $\pi \sqrt{2}$ double-focussing $\beta$-ray spectrometer. The internal-conversion-electron spectrum revealed the presence of $\gamma$ rays of 609.89(24), 556.85(22), 496.88(16), 443.85(15), 294.88(16), 53.11(3), and 39.55(4) keV. No new lines with an intensity greater than 1.6% of the $497K$ line were found. The $67K$ line was found to have an intensity less than 0.17%, and the $322K$ and $362K$ lines an intensity less than 0.3%, of the $497K$ line. Limitations on the multipolarities and mixing ratios of some of the transitions have been determined through $\frac{K}{L}$- and $L$-subshell ratios, and through internal-conversion-coefficient measurements. The multipolarities obtained for the seven observed transitions were compared with $\gamma -\gamma$ angular-correlation results. This resulted in the spin-parity assignments of ${\frac{7}{2}}^{+}$, ${\frac{7}{2}}^{+}$, and ${\frac{7}{2}}^{-}$ for the 39.55(4)-, 92.66(5)-, and 649.48(24)-keV states, respectively. The 536.47(16)-keV level is shown to have a spin parity of either ${\frac{3}{2}}^{+}$ or ${\frac{7}{2}}^{-}$.

• Received 4 May 1967

DOI:https://doi.org/10.1103/PhysRev.165.1363