Mark L. Roberts   Email     Print   PDF

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Senior Research Specialist
Geology & Geophysics
mroberts@whoi.edu

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Mark Roberts, staff physicist is working on an initiative to re-determine the ¹⁴C half-life. This initiative was developed in response to questions raised by various researchers at Lamont-Doherty Earth Observatory (Broecker, 2005; Fairbanks, 2005; Chiu, 2007), who pointed to uncertainties about the validity of the 'accepted' ¹⁴C half-life. These groups suggested that the currently accepted half-life of 5700 ± 30 years might be too low. A significant shift in the ¹⁴C half-life would impact our understanding of the ¹⁴ C calibration curve. Preliminary results, in which the ¹⁴C half-life is determined from knowledge of both the specific-activity and ¹⁴C/¹²C ratio of the ¹⁴C counting standard OX-I, indicate that the currently accepted half-life might actually be 1-2% too high. A paper summarizing the work has been recently accepted for publication in Radiocarbon.

References
Broecker W and Barker S, (2005) ‘A 190 per mil drop in atmosphere’s Δ¹⁴C during the “Mystery Interval” (17.5 to 14.5 kyrs)?’, submitted to Quaternary Science Reviews.

Fairbanks RG, Mortlock RA, Chiu T-C, Cao L, Kaplana A, Guilderson TP, Fairbanks TW, Bloom AL, Grootes PM, and Nadeau M-J, (2005) ‘Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired ²³⁰Th/²³⁴ U/²³⁸ U and ¹⁴C dates on pristine corals, Quaternary Science Reviews 24, 1781–1796.

Chiu T-C, Fairbanks RG, Cao L, and Mortlock RA, (2007) ‘Analysis of the atmospheric ¹⁴C record spanning the past 50,000 years derived from high-precisions ²³⁰Th/²⁴⁴U/²³⁸U, ²³¹Pa/²³⁵U and ¹⁴C dates on fossil corals’, Quaternary Science Reviews 26, 18-36