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 (t1/2=2.744 yr) with accelerator mass spectrometry. Our result of (2.50±0.12)×10(6) yr clearly favors the recently reported value (2.62±0.04)×10(6) yr, and rules out the older result of (1.49±0.27)×10(6) yr. The present weighted mean half-life value of (2.60±0.05)×10(6) 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.