Settling the Half-Life of 60Fe: Fundamental for a Versatile Astrophysical Chronometer

In order to resolve a recent discrepancy in the half-life of ⁶⁰Fe, we performed an independent measurement with a new method that determines the ⁶⁰Fe content of a material relative to ⁵⁵Fe (t_{1 /2}=2.744 yr ) with accelerator mass spectrometry. Our result of (2.50 ±0.12 )×10⁶ yr clearly favors the recently reported value (2.62 ±0.04 )×10⁶ yr , and rules out the older result of (1.49 ±0.27 )×10⁶ yr . The present weighted mean half-life value of (2.60 ±0.05 )×10⁶ yr substantially improves the reliability as an important chronometer for astrophysical applications in the million-year time range. This includes its use as a sensitive probe for studying recent chemical evolution of our Galaxy, the formation of the early Solar System, nucleosynthesis processes in massive stars, and as an indicator of a recent nearby supernova.