A survey was made of the neutron-deficient activities of terbium produced by proton bombardment of enriched isotopes of gadolinium. Half-lives and mass assignments are made for ${\mathrm{Tb}}^{156}$ and ${\mathrm{Tb}}^{154}$, and the limits of half-lives for ${\mathrm{Tb}}^{158}$, ${\mathrm{Tb}}^{157}$, and ${\mathrm{Tb}}^{155}$ are defined. Data were obtained on the gamma-ray spectrum of ${\mathrm{Tb}}^{156}$.

• Received 8 April 1955

DOI:https://doi.org/10.1103/PhysRev.99.1415