Prediction of new isotopes of radon

The decay properties of Radon isotopes in the mass range ^190-280Rn were systematically investigated using well-established theoretical models. The half-lives for α, β^-, β⁺/electron capture (EC) and spontaneous fission (SF) were evaluated using the Unified Fission Model for α decay and semi-empirical relations for β/EC-decay and SF. Shell correction, angular momentum and parity were incorporated in the evaluation of decay half-lives. For each isotope, the most probable decay mode was determined by comparing the calculated half-lives of all competing decay channels. Based on the theoretical predictions, a total of 54 energetically feasible radon isotopes were obtained within the considered mass range, with decay Q-values spanning approximately 3.27-17.38 MeV. Among them, 51 isotopes were found to favor β^- decay while only 3 isotopes preferentially undergo α decay as the dominant mode. The present calculations show good agreement with the available experimental data, supporting the reliability of the adopted models. The predicted decay characteristics may serve as a reference for future measurements in experimentally unexplored regions of the radon mass chain.