Energy Levels and γ-Ray Transitions in¹⁴⁹Pm

Abstract

Gamma-gamma angular correlations have been measured for 25 cascading transitions in 149 Pm following the decay of 1.7–h 149 Nd. The spins of the 288.21-, 425.30- and 515.66-keV levels in 149 Pm have been assigned as 9/2, 7/2 and 9/2, respectively. The E2/M1 mixing ratios of 15 transitions have been derived. A new level at 872.32 keV has been introduced from the results of γ-ray singles and γ–γ coincidence measurements. Experimental level energies and E2/M1 mixing ratios have been compared with predictions based on current theoretical models.