부산대학교 도서관

The decay of the two Pm/sup 148/ activities produced by neutron irradiation of fission-product Pm/sup 147/ was studied. The half-lives are 5.39 plus or minus 0.06 and 40.6 plus or minus 0.4 days. The energies and relative intensities of the gamma radiation emitted in the decay of the 5.4-day activity were 0.550 (1.00), urements and scintillation spectra indicated the existence of a beta branch of ~2.6 Mev from the 5.4-day state in Pm/sup 148/ to the Sm/sup 148/ ground state. The decay of the 41-day activity gives rise to gamma rays in Sm/sup 148/ whose energies and relative intensities are 0.098 (0.032), 0.188 (~0.01), gamma and beta-gamma coincidence experiments, with the gamma-ray energies and relative intensities, indicate the existence in Sm 46 of levels at 0.55, 1.18, 1.46, 1.59. 1.90, relation measurements were made on all the prominent gamma-ray cascades and provided spin assignments for many of the observed states. The conversion-electron spectrum of 41-day Pm/sup 148/ indicates transitions of 60 and 75 kev in Pm and establishes that the 41-day activity is an isomeric state. A (6.5 plus or minus 1.7)% isomeric-transition branch was observed for this state. Properties of the low-lying states of Pm/sup 148/ are discussed. Decay schemes for the Pm/sup 148/ activities are proposed. (auth)