New Terbium Isotope,Tb152

A careful examination of photon and electron spectra from cyclotron-produced mixtures of light terbium isotopes has led to the identification of a new isotope, ${\mathrm{Tb}}^{152}$, with an 18.5-hr half-life. The 344.1-kev transition from first excited state to ground in daughter ${\mathrm{Gd}}^{152}$ has been identified and shown to be identical in energy to a transition associated with the beta decay of 9.3-hr ${\mathrm{Eu}}^{152m}$ to the same daughter nucleus. Gamma transitions of 180 and 265 kev are also assigned to the decay of ${\mathrm{Tb}}^{152}$.