The deformedN=60 nucleus 41 101 Nb

The ^– decay of¹⁰¹Zr has been investigated at the fission-product separators JOSEF and LOHENGRIN. The half-life of¹⁰¹Zr has been determined to 2.5(1) s and a level scheme for¹⁰¹Nb has been established from ray singles as well as X/3- and — coincidence measurements. Conversion coefficients for transitions in¹⁰¹Nb and level half-lives between 10 ps and 2 ns have been determined. Three rotational bands are identified among the low-lying levels with band heads at 0 keV, 206 keV and 208 keV. The bands are probably based on the Nilsson configurations [422 5/2⁺], [301 3/2^–] and [303 5/2^–], respectively. The deformation has been determined to _q=0.40(4) and 0.41(8) for the ground state band and the band based on the 206 keV level from the half-lives of the first and second excited members of these bands. This shows that the rapid onset of deformation at N=60 which is typical for the A=100 region of neutron-rich nuclei, takes also place in the Nb isotopes. Nilsson model calculations describe the experimental data well, especially the several determined transition probabilities including those for E1 transitions from the 206 and 208 keV band heads to the ground state.Dedicated to Prof. Dr. P. Armbruster on the occasion of his 60th birthday