Detailed investigation of the β-decay of the 9/2+ ground state of 99Nb to levels in 99Mo

The decay of 99Nb to 99Mo has been investigated. The use of the ion-guide technique for on-line mass separation and of a Ge-array for γ-ray detection have allowed the observation of decay branchings lower than 10-3. Medium-spin levels, some already known from reaction studies and new ones at high energy, are populated. The β-feeding patterns of the decays of the 9/2+ states in 99Nb and in its isotones 97Y, and 101Tc are qualitatively reproduced by QRPA calculations. (orig.). With 5 figs., 7 tabs