No abstract

Abstract. After bombardments of enriched 152Sm with 14-MeV neutrons, three isomers of ~ s 2 Pm, produced by the (n, p) reaction, have been observed with half-lives of 4.2 _+ 0.2 min, 7.5+0.2min and 15.0+ 1.0 rain. Sources of pure 4.2-rain ~S2pm were obtained by separating the promethium from its parent ll-min 152Nd produced by thermal-neutron induced fission of 235U. The beta and gamma radiations of the 4.2-min 152pm have been investigated using semiconductor and scintillation spectrometers. Most of the y-ray transitions could be placed in a level scheme for ~SZSm. Especially interesting is a level at 1 083 keV for which the assignment U =0 + is proposed. In a 4g/~ 7 experiment, the ground state feeding of 152Sm in the /~--decay of the 4.2-rain ~52Pm has been measured to be 61 o/o of all/%ray transitions. A Q/j-value of 3.4 + 0.2 MeV has been obtained.