Algebraic approach to the structure of the low-lying states in A ≈ 100 Ru isotopes

The structure of the low-lying states in the odd-and even-mass A approximate to 100 Ru isotopes is studied in the framework of two algebraic models. The even-mass Ru nuclei are first described within the interacting boson model 1 (IBM-1). The output of these calculations was then used to calculate the odd-A isotopes within the interacting boson-fermion model 1 (IBFM-1), where a coupling of the odd neutron to the even-even core is considered. The level energies and transition probabilities calculated in the present work are tested against the experimental data. One-nucleon transfer spectroscopic factors as well as electromagnetic moments were also calculated for the odd-A Ru and compared to the experimental values. The transitional character of the isotopes is studied. Most of the low-lying positive-parity states in the odd-A Ru nuclei below 2 MeV are interpreted on the basis of nu d(5/2) and nu g(7/2) configurations. The role of the nu s(1/2) orbital in the nuclear structure of the odd-mass Ru nuclei at low energies is also studied. The negative-parity states are interpreted as nu h(11/2) excitations coupled to the core. The evolution of the IBM-1 and IBFM-1 parameters is discussed.