Abstract
The 9-delayed gamma-ray spectroscopy of 109Nb was performed to investigate the structure of 109Mo for the first time at the RIBF, Japan. Over one hundred transitions were assigned to 109Mo, of these two were from the known isomeric state, and a new 33.1 keV excited state below the isomeric state was identified. The multipolarities of the transitions depopulating the isomeric state were restricted considering the internal conversion coefficients and empirically recommended upper limits of transition strengths. The intrinsic gyromagnetic ratio of the isomeric-state band was extracted, and the rotational band of the ground state was identified. The configurations of the ground and isomeric states in 109Mo were assigned to the v1/2+[411] and v5/2+[413] orbitals, respectively, with prolate shape. From the log ft analysis, the ground state in 109Nb and a new excited state in 109Mo with a small log ft value were assigned to the r5/2+[422] and v5/2+[402] orbitals, respectively. The assignments were supported by potential energy surface calculations using the configuration-constrained method with a triaxially deformed Woods-Saxon potential. Although the v1/2+[411] orbital was successfully predicted as the ground state, the order of quasiparticle configurations for excited states was not reproduced. The neutron emission probability in 109Nb ,B-decay was evaluated to be 27(11)% utilizing the ,B-delayed gamma rays of 109Tc and 108Mo.