Nuclear Levels inDy161

Abstract

A specimen of ${\mathrm{Gd}}^{160}$ enriched from its normal 21.9% up to 95.4% was irradiated in the Argonne heavy water pile. The ${\mathrm{Gd}}^{161}$ formed by neutron capture decays by beta and gamma emission with a half-life of 3.7 min to radioactive ${\mathrm{Tb}}^{161}$. Spectrometric studies of this activity show it to decay with a half-life of 7.15 days emitting both beta and gamma rays many of which previously have not been evaluated. There appear to be seven gamma rays in Dy, all internally converted, whose energies are: 25.6, 27.7, 48.9, 57.3, 74.8, 78.3, and 106.2 kev. These energies fit into a scheme with nuclear levels at 25.6, 74.8, 103.9, and 132.0 kev. Coincidence data with the scintillation spectrometer support the proposed plan. The beta spectrum, studied with the double focusing spectrometer, appears to be complex, having three components whose energies are 531, 447, and 405 kev, with relative intensities of 68%, 22%, and 10%, and $log\mathrm{ft}$ of 6.7, 6.9, and 7.2, respectively.