Description of nuclei in the A ~ 100 mass region with the interacting boson model

Even–even nuclei in the A ~ 100 mass region are investigated within the framework of the interacting boson model-1 (IBM-1). The study includes energy spectra and electric quadrupole transition properties of zirconium, molybdenum, ruthenium and palladium isotopes with neutron number N ≥ 52. A global parametrization of the IBM-1 Hamiltonian is found leading to a description of about 300 collective levels in 30 nuclei with a root-mean-square deviation from the observed level energies of 120 keV. The importance of the d5/2 subshell closure at neutron number N = 56 is pointed out. The geometric character of the nuclei can be visualized by plotting the potential energy surface V(β, γ) obtained from the IBM-1 Hamiltonian in the classical limit. The parametrization established on the basis of known elements is used to predict properties of the unknown, neutron-rich isotopes 106Zr, 112Mo, 116Ru and 122Pd.