However, new isotopes of carbon-14 continue to be formed in our atmosphere, and after a few years the percent of radioactivity in an old object is less than it is in a newer one. By measuring this difference scientists are able to determine how old certain objects are. The measuring process is called carbon dating. I am sure that you already know that detectives often search the scene of a crime for traces of paint, glass, hair, gunpowder, or blood. But you may not know that after such evidence is collected, it is often exposed to radiation and then analyzed to find out its exact makeup.
Radiation can activate some of the elements in most materials by adding neutrons to their nuclei.
This makes those elements slightly radioactive. Scientists are then able to read the exact chemical signatures of these substances. This laboratory process, called activation analysis , is precise enough to tell if a single hair found at the scene of a crime came from a certain person. Activation analysis is also used to find out the chemical makeup of materials when scientists only have small samples, as well as to prove that older works of art are not made of modern materials. We could talk all day about the many and varied uses of radiation in industry and not complete the list.