Reinvestigation of the Decays of Eu146 and Pm146 and the Existence of Two Close-Lying States at ~1381 keV in Sm146
The decays of Pm146 and Eu146 have been reinvestigated with the primary purpose of establishing the character of the second excited state previously reported at 1384 keV in Sm146. Gamma-gamma directional correlation data obtained from studies of both the beta decay of Pm146 and the electron capture and positron decay of Eu146, along with the K-shell internal-conversion-coefficient data, establish the existence of two close-lying states in Sm146 at 1380.7 and 1382.0 keV with spins and parties 3- and 4+, respectively. The gamma-ray spectra were studied with a lithium-drifted germanium detector. In the beta decay of Pm146 the feeding of the 3- state is at least 9.7 times that to the 4+ state, while in the decay of Eu146 the total feeding to the 3- state is ~1.2 times that to the 4+ state. In addition, gamma-ray energies and intensities are presented for the transitions observed in the decay of Pm144 to Nd144 and Pm146 to Nd146 and Sm146, and for some of the more intense transitions observed in the decay of Eu146. Energy systematics of 3- and 4+ states for even-even nuclei in the transition region A=142 to 152 are presented.