Absolute radiometric dating direct dating of human fossils
Plants and animals assimilate carbon 14 from carbon dioxide throughout their lifetimes.
This scintillator produces a flash of light when it interacts with a beta particle.
A vial with a sample is passed between two photomultipliers, and only when both devices register the flash of light that a count is made.
It must be noted though that radiocarbon dating results indicate when the organism was alive but not when a material from that organism was used. Samples that have been radiocarbon dated since the inception of the method include charcoal, wood, twigs, seeds, bones, shells, leather, peat, lake mud, soil, hair, pottery, pollen, wall paintings, corals, blood residues, fabrics, paper or parchment, resins, and water, among others.
Physical and chemical pretreatments are done on these materials to remove possible contaminants before they are analyzed for their radiocarbon content.
American physical chemist Willard Libby led a team of scientists in the post World War II era to develop a method that measures radiocarbon activity.