A 3.7-hour activity, assigned to ${\mathrm{Y}}^{84}$, has been obtained by bombardment of ${\mathrm{Sr}}^{84}$ with 10-Mev deuterons. Characteristic radiations are 2.0-Mev positrons, x-rays, and gamma-rays. A 2.0-hour activity, assigned to ${\mathrm{Zr}}^{87}$, has been obtained by bombarding natural strontium and ${\mathrm{Sr}}^{84}$ with 20-Mev alpha-particles. Characteristic radiations are 2.0-Mev positrons, x-rays, and gamma-rays. Bombardments of ${\mathrm{Sr}}^{87}+d$, $Y+n^f$, and $\mathrm{Rb}+\alpha$ are in agreement with the assignment of a 105-day activity to ${\mathrm{Y}}^{88}$ but show no evidence of a 2.0-hour positron activity previously assigned to ${\mathrm{Y}}^{88}$.

• Received 24 August 1949

DOI:https://doi.org/10.1103/PhysRev.76.1649