Which unit is used to measure radioactive decay?

The unit used to measure radioactive decay is the Curie. This unit specifically quantifies the activity of radioactive material. One Curie is defined as the amount of radioactive material that will produce 3.7 x 10^10 disintegrations per second, which reflects the rate of decay of radioactive isotopes. The Curie is particularly useful in radiation protection and nuclear medicine, as it helps in understanding the strength and behavior of radioactive sources.

The other units mentioned serve different purposes in the context of radiation. Roentgen measures the exposure to ionizing radiation in air, primarily focusing on the amount of radiation that produces ionization. Gray is a unit that quantifies absorbed dose, indicating the amount of energy deposited in material by radiation. Sievert measures the biological effect of ionizing radiation, considering the impact on human tissue. Each of these units plays a significant role in the field of radiation protection and health physics, but they do not specifically measure the rate of radioactive decay like the Curie does.