Investigating the level structure of 206Rn: evolution from seniority regime to collective dynamics

Excited states of 206Rn have been studied via the 197Au(14N, 5n)206Rn fusion reaction at a beam energy of 78 MeV. A number of transitions and levels are identified by the γ-γ coincidence measurement, further enriching the level scheme of 206Rn. Both the full configuration shell model and the nucleon-pair approximation (NPA) were utilized to investigate the single-particle configurations and seniority structures in 206Rn. The results of these two calculations suggest that the 21 + and 41 + states exhibit only a 50% component of a seniority-two state associated with a broken neutron pair. The collectivity of these two states primarily arises from configuration mixing due to residual proton-neutron interactions. The 61 + and 81 + states are predominantly characterized by a seniority-two state marked by a broken proton pair.