1. Radiocarbon Dating Daniel De Schepper NCSS

2. Conception • 1946 suggests that 14C exists in living matter • Confirmed a year later • 1949 found that several trees contained roughly the same amount of activity due to 14C • 1960 won Nobel prize Willard Libby

3. Atmospheric neutron intensity and 14C production • 14N + 1n 14C + 1H • CO2 undergoes rapid equilibrium in the atmosphere

4. Assumptions • 14C production is constant • The biosphere and atmosphere have roughly the same 14C concentration • After death there is no 14C exchange and it is only affected by radioactive decay

5. Some Deviations • Glacial effects • Human activity • Variations in natural production rate

6. Glacial effects CO2 solubility is temperature dependant

7. Human activity Fossil fuel (Suess) effect and bomb effect

8. Variations in production rate Major cause of Suess wiggles

9. The need for calibration • Dendrochronology X-axis spans 2000 calendar years Y-axis is in radiocarbon age (BP) where 0 BP = 1950 AD

10. Unearth sample Physical separation Treat with acid Convert carbon to CO2 via combustion Remove impurities (ie nitrogen oxides, sulfur, products of incomplete combustion, and radon) Isolate carbon: 2 Mg + CO2 MgO + C Limit exposure to air SamplePreparation

11. Accelerator Mass Spectrometer • Upper age limit 40,000 years • Lower age limit 200 years

12. Archaeology 1423 to 1445 AD* 1260 to 1390 AD* * Radiocarbon date 3100 to 4000 BC*

13. Conclusions • There are errors in radiocarbon dating due to assumptions  this calls for calibration • With this radiocarbon dating can be used to determine the age of a given sample • Though variation still persists