Energy Levels inSr86from the Decay of 14.6-hY86

The radioactive decay of ${}_{}{}^{86}{}_{}{}^{}\mathrm{Y}$ has been investigated by performing internal- and external-conversion measurements with an iron-free double-focusing $\beta$-ray spectrometer, $\gamma$-ray measurements with Ge(Li) spectrometers, and $\gamma -\gamma$ coincidence experiments with NaI-NaI, NaI-Ge-(Li), and Ge(Li)-Ge(Li) coincidence arrangements coupled to two-parameter analyzers. Coincidence relationships were used extensively to aid in the construction of a level scheme for ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$. Excited states are established at 1076.63, 1854.20, 2229.68, 2481.91, 2642.27, 2672.76, 2788.2, 2878.28, 2997.34, 3055.66, 3185.19, 3291.08, 3317.58, 3362.06, 3499.84, 3555.71, 3644.94, 3686.74, 3765.59, 3774.80, 3831.06, 3871.53, 3925.89, 3942.41, 3968.84, 4146.0, 4206.00, 4339, 4410.5, 4718, and 4954 keV. The $K$ conversion coefficient was directly measured for the 1076.63-keV transition and this transition was used to obtain $K$ conversion co-efficients from the relative $\gamma$-ray intensities and the relative conversion-electron intensities. A new decay scheme is proposed which removes the inconsistencies of the older scheme and gives a much more detailed picture of the decay properties of the ${}_{}{}^{86}{}_{}{}^{}\mathrm{Y}$ nucleus.