DECAY PROPERTIES AND LIFETIMES OF STATES IN SM-144 FROM (N, N'GAMMA) REACTION STUDIES

An extensive investigation of Sm-144 has been carried out with the (n, n'gamma) reaction. Gamma-ray excitation function and angular-distribu tion measurements were performed at neutron energies up to 4.3 MeV. Ma ny new levels have been established and characterized, and the assignm ents of several previously known states have been clarified. Level lif etimes were measured following the inelastic neutron-scattering reacti on by observing the Doppler shifts of de-exciting gamma-rays, and redu ced transition rates have been inferred. Recent shell-model calculatio ns were found to describe the Sm-144 level scheme very well up to 3.2 MeV. A large number of relatively fast E1 transitions were observed.