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

Excited states of have been examined via the ( , 5 n ) 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 . The full configuration shell model and nucleon-pair approximation (NPA) were utilized to investigate the single-particle configurations and seniority structures in . The results of these two calculations suggest that and 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. Furthermore, and states are predominantly characterized by a seniority-two state marked by a broken proton pair.