β decay of the 21/2^{+} isomer in ^{93}Mo and level structure of ^{93}Nb

The gamma rays associated with beta decay of the 21/2(+) isomer in Mo-93 (E-x = 2.425 MeV, T-1/2 = 6.85 h) were measured with a selective sensitivity to long-lived isomer decays. A new 1262-keV transition was found in the gamma-gamma coincidence measurement, and it was attributed to a transition in Nb-93, which is the daughter nucleus of the beta decay of the Mo-93 isomer, from the 2.753- to the 1.491-MeV levels. Accurate gamma-ray intensity balances have determined the beta-decay intensity from the Mo-93 isomer to the 2.753-MeV level in Nb-93 and placed no appreciable intensity for the previously reported beta-decay branching to the 2.180-MeV level, for which a recent in-beam gamma-ray experiment assigned to be I-pi = 17/2(-). Based on the gamma-ray intensities from the 2.753-MeV level, spin-parity assignment of this level was revised from 21/2(+) to 19/2(+). The observed beta-decay intensity and the spin-parity assignment were explained by the jj-coupling shell model calculations.