Transition Energies and Nuclear Levels in Sm152, Sm154, Gd152, and Gd154 as Derived from the Separated Isotopes of Europium

Abstract

Specimens of highly enriched ${\mathrm{Eu}}^{151}$ and ${\mathrm{Eu}}^{153}$ were irradiated in the Argonne CP-5 reactor and the product isotopes studied in both magnetic and scintillation spectrometers. ${\mathrm{Eu}}^{152}$ decays by electron emission to ${\mathrm{Gd}}^{152}$ and by $K$ capture to ${\mathrm{Sm}}^{152}$. ${\mathrm{Eu}}^{154}$ emits beta particles leading to ${\mathrm{Gd}}^{154}$ but no evidence appeared for positron emission or $K$ capture leading to ${\mathrm{Sm}}^{154}$. The many conversion-electron lines together with coincidence data allowed the evaluation of the gamma transitions and their arrangement in plausible nuclear level schemes. The beta spectra were resolved by the use of the double-focusing spectrometer. Each of the daughter nuclei is even-even in structure. A comparison is made of the observed lower energy transitions and the prediction from the "collective" model for rotational states.