Novel spectroscopic study of radium isotopes using the interacting boson model with negative parity degrees of freedom

We present a systematic study of the low-lying positive and negative parity states of the $^{216--228}\mathrm{Ra}$ isotopic chain in the context of the $spdf$ interacting boson model $(spdf\text{\ensuremath{-}}IBM\text{\ensuremath{-}}1)$. The goal is to reproduce the experimental data for the level energies and the electromagnetic transition rates between them of these isotopes using a reduced set of Hamiltonian parameters. To do this task, a minimization routine based in minuit was used. Also the potential energy surfaces were obtained and their minima show a transition from spherical to deformed shapes when the neutron number increases throughout the isotopic chain.