Investigation of gamma rays in the decay chain [formula omitted

Abstract

Gamma-ray spectra were measured with a Ge(Li) detector for the decay chain 149 Gd(9 d)→ 149 Eu(106 d)→ 149 Sm . Results were compared with previously known data for transitions following the decay of the same two nucleides. By combining several sets of conversion-electron and γ-ray intensities, K-shell internal conversion coefficients were calculated for and probable multipolarities were assigned to 149Gd transitions that had been observed in both γ-ray and conversion-electron spectra. These transition intensities and multipole orders were found to be consistent with a partial decay scheme that features excited states in 149Eu at energies of 149.8, 496.6, 534.4, 666.6, 749.1, 795.1, 939.1, 956.1 and 1097.8 keV. Intensities measured in this study for γ-rays following 149Eu decay were found to agree with a recently published set of intensity values. Here again, K-shell internal conversion coefficeints were calculated by combining conversion-electron and γ-ray data. An e-γ[Ge(Li)] coincidence measurement yielded additional evidence for the existence of 149Sm excited levels at energies of 22.5, 277.0, 350.0 and 528.5 keV.