Abstract
Mass-separated 187Ta114 in a high-spin isomeric state has been produced for the first time by multinucleon transfer reactions, employing an argon gas-stopping cell and laser ionization. Internal γ rays revealed a T1/2 = 7.3 ± 0.9 s isomer at 1778 ± 1 keV , which decays through a rotational band with perturbations associated with the approach to a prolate-oblate shape transition. Model calculations show less influence from triaxiality compared to heavier elements in the same mass region. The isomer-decay reduced E 2 hindrance factor fν = 27 ± 1 supports the interpretation that axial symmetry is approximately conserved.