Carbon dating nuclear testing
Standing outside the low, gray industrial building, she watched as horses went in one side and, about 15 minutes later, a worker appeared on the other end, holding a head, neurons and all.“It was precisely as revolting as it sounds,” she says.3.5 decays/gram/minute of carbon would be produced by a sample 11,460 years old.
The idea behind radiocarbon dating is straightforward, but years of work were required to develop the technique to the point where accurate dates could be obtained.By the time a halt was called to aboveground nuclear testing in 1963, levels of carbon-14 in the atmosphere had doubled beyond natural background levels, says Frisén. By taking this into account, one can see detectable changes in levels of carbon-14 in modern DNA, he says."Most molecules of the cell will turn over all the time.The radiocarbon dating method is based on the fact that radiocarbon is constantly being created in the atmosphere by the interaction of cosmic rays with atmospheric nitrogen.
The resulting radiocarbon combines with atmospheric oxygen to form radioactive carbon dioxide, which is incorporated into plants by photosynthesis; animals then acquire in a sample from a dead plant or animal such as a piece of wood or a fragment of bone provides information that can be used to calculate when the animal or plant died.Other corrections must be made to account for the proportion of throughout the biosphere (reservoir effects).