Radiocarbon dating

Radio carbon dating

1. RADIO CARBON DATING GOKUL UK NO:25 MS6

2. Contents Introduction. History Carbon 14 Basic concept of radio carbon dating Dating sample Carbon dating methods Applications Impact Limitations Conclusion

3. Introduction Radiocarbon dating/carbon14 dating Method for age determination of object containing organic material Depends up on the decay of radio carbon

4. History Developed in the late 1940 at university of chicago Willard Libby is the founder of carbon dating. Won Nobel prize in 1960 Newly discovered radioactive isotope of carbon Radio carbon revolution helped more precise historical chronologies across geography and cultures

5. Willard libby's concept of carbon dating Radio carbon dating in 1945 Inspired by phisicist Serge korff C14 in the atmosphere find its way to living matter If one could detect the amount of carbon 14 in an object that objects age can be established Object age can be established using rate of decay.

6. Carbon 14 Radioactive isotope of carbon Contains 6 protons and 8 neutrons Discovered by Martin kamen and Samu Ruben Naturally occuring isotope Natural source of carbo 14 on earth Is cosmic ray action on nitrogen in atmosphere Has a half life of 5730+_30 years

7. Basic principle of carbon dating Carbon 14 continually formed in the upper atmosphere Effect of cosmic ray neutron on nitrogen 14 atoms produce C14 Rapidly oxidized in air to form carbondioxide enters global carbon cycle Plants and animals accumulate C14 throughout their life times Stop exchanging carbon with biosphere when they die C14. Content decreased by the law of radio active decay

8. Measuring the amount of carbon 14 the age can be estimated Ratio between C12 and C14 approx same in living time When it dies C14 decays to Nitrogen14 By measuring ratio of C12 to C14 after death can be used to estimate the age.

9. Half life of radioactive isotope Amount of time takes to half the number of isotope in a sample to decay Half life for carbon 14 is 5730 years Relatively small span More than 60000 years is not possible Every 5730 years C14 content is halfed

10. Dating sample Samples containing organic matter Handled carefully to avoid contamination Should converted to suitable form Contaminants removed by pre treatment Sample sizes based on testing technologies

11. Carbon dating methods Gas proportional counting Liquid scintillation counting Accelerator mass spectrometry

12. Gas proportional counting Conventional radiometric dating technique Counts beta particles emitted by sample Beta particles are product of radiocarbon decay Carbon sample is converted to carbondioxide gas for counting

13. Liquid scintillation counting Popular technique in the 1960’s Sample is in liquid form Scintillator is added Scintillator produces flash light while interacting with beta particle Photomultiplier tubes transfer this light signal Used for alpha and beta particle detection

14. Accelerator mass spectrometry Modern radio carbon dating method More efficient way to measure radio carbon content Carbon 14 content is directly measured to carbon 12 and carbon13 present in sample Beta counting is not required

15. Applications Archeology Geology Hydrology Geophysics Atmospheric science Oceanography Bio medicine

16. Impact Modern man made it one of the most significant discoveries of the 20 th century Revolutionizes man’s understandings on events that allready happened thousands of years ago Prove and disprove theories

17. Limitations Dating is not possible for samples older than 60,000 years. Dating is possible only for objects containing organic material. Objects that are parts of living things only could be dated. Emission from fossil fuels limit carbon dating.

18. Conclusion Carbon dating technology is effective technology to find out age of objects upto 60,000 years old. Most of every field of science utilises carbon dating Carbon dating is in danger due to excess burning of fossil fuel.

19. Radiocarbon Dating Endangered by Air Pollution

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