First observation of isomeric transition from ^{148 m}Pr and parity assignment for excited levels in ¹⁴⁸Pr

Internal conversion electrons from the decay of Ce-148 and Pr-148m have been measured with a Si(Li) detector. The radioactive sources were produced by the thermal neutron-induced fission of U-235, followed by an on-line mass separation. K- and L-conversion electrons of the isomeric transition from Pr-148m were newly observed at 34.6 and 70.8 keV, respectively. The M3 multipolarity was assigned to this transition from the experimental conversion coefficients, and, consequently, the 76.8 keV isomeric level was found to be a 4(-) state. Parities of some excited levels in Pr-148 were also deduced.