Decay of ¹⁵⁴Pm to Levels of ¹⁵⁴Sm

Abstract

Decay of 154 Pm isomers has been studied with Ge(Li), NaI(Tl) and plastic detectors. Sources were prepared by the 154 Sm(n, p) 154 Pm reaction with about 15 MeV neutrons. Seventy-five γ-rays have been observed and 57 of them are assigned to the 154 Sm level scheme including four new levels at 1815.8, 1879.3, 2592.3 and 2618.8 keV. Observed Q β values were 3.9±0.2 MeV. Most probable spin assignments of 0 ± or 1 ± and 3 ± or 4 ± are proposed for the 1.7±0.2 min and 2.9±0.2 min 154 Pm, respectively.