Beta‐decay of 27/2− isomers in N=83 nuclei

In theN=83 nucleus151Er we observed the isomericE3 transition in conversion electron measurements following on-line mass separation and located its 0.6 s 27/2− isomer at 2.586 MeV. Gamma-ray data establish a 4.7(3)% Gamow-Tellerβ-decay branch proceeding to high-spin states above 2 MeV excitation in151Ho. A weakβ-decay branch of 0.7(3)% was also observed for the 0.5 s 27/2− isomer in the149Dy isotone, and it was established that a similar 27/2−E3-isomer does not occur in153Yb. First results on the151Tm and151Er ground-stateβ-decays are briefly discussed.