Calibration of the α-decay half-life of 146Sm for the chronology of early solar system

The α -decay half-life of extinct 146 Sm serves as a crucial tracer for analyzing the geological activities of planets in the early solar system. Despite its critical importance, the precise determination of 146 Sm’s half-life has long presented significant challenges. The reported half-life values exhibit a bimodal distribution and two substantially different values are recommended by the IUPAC-IUGS joint Task Group “Isotopes in Geosciences”. This poses a rather puzzling situation and leads to considerable uncertainty in tracing planetary mantle differentiation events. In this work, we report a high-precision determination of 146 Sm’s half-life ( T 1 / 2 = 78 . 1 − 7.6 + 7.6 Ma) using the state-of-the-art α -decay model, in which the α -cluster formation and the Pauli blockings for imbalanced systems are properly handled for the first time. We also provide new constraints for the ages of differentiation events on Earth, Mars and the Moon that occurred in the early solar system. Our results not only enhance the understanding of the α -decay process based on first principles calculations but also offer valuable insights into the early evolution of the solar system.