Radioactive isotopes formed by bombardment of Rb, Sr and Y by protons, deuterons and neutrons are reported. The following are the periods and assignments: 2.75-hr. (${\mathrm{Sr}}^{87*}$, $e^{-}$, $\gamma$); 70-min. (${\mathrm{Sr}}^{85}$, $e^{-}$, $\gamma$); 66-day (${\mathrm{Sr}}^{85}$, $\mathrm{K}$, $\gamma$); 80-hr. (${\mathrm{Y}}^{87}$, K); 14-hr. (${\mathrm{Y}}^{87}$, $e^{-}$, $\gamma$); 105-day (${\mathrm{Y}}^{86}$, $\mathrm{K}$, $\gamma$); 4.5-min. (${\mathrm{Zr}}^{89}$, $\gamma$); 78-hr. (${\mathrm{Zr}}^{89}$, ${\beta }^{+}$). (In each case $e^{-}$ means conversion electrons, not nuclear $\beta$-rays.) The electron spectrum of the 2.75-hr. ${\mathrm{Sr}}^{87*}$ shows a single line at 360 kev and this period is shown to grow from the 80-hr. ${\mathrm{Y}}^{87}$, but not from the 14-hr. isomer.

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