American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

Gamma ray decay is most commonly measured in curies, which quantifies the amount of radioactive material and its rate of decay. The curie is based on the disintegration of one gram of radium-226 per second, which provides a clear measure of the activity of a radioactive source. This is particularly relevant for gamma rays, as they are emitted during the decay of radioactive nuclei.

Other units, such as gray and sievert, are more focused on measuring radiation doses and effects on biological tissue rather than the rate of decay itself. The gray is used to express absorbed dose, while the sievert indicates the biological effect of radiation exposure. Röntgen measures exposure to ionizing radiation in air but does not specifically address the concept of radioactive decay. Therefore, in contexts surrounding gamma ray activity and decay measurement, the curie is the most appropriate and widely utilized unit.