Decay ofSm15562(23.5 min)

Abstract

The decay of ${\mathrm{Sm}}^{155}$(23.5 min) is characterized by beta emission to excited states in ${\mathrm{Eu}}^{155}$. This activity was studied by means of the Argonne 256-channel scintillation coincidence spectrometer. Sources were prepared by neutron irradiation of samarium oxide, enriched in ${\mathrm{Sm}}^{154}$, in the Argonne reactor CP-5. Three gamma-ray transitions and two beta-ray branches are reported. These radiations are fitted into a decay scheme which indicates the presence of excited states in ${\mathrm{Eu}}^{155}$ at 105 and 246 kev. The total decay energy is found to be 1.8±0.1 Mev. Possible spin and parity assignments for each of the levels are discussed.