Specific activity Specific activity Specific activity is the activity per quantity of a radionuclide and is a physical property of that radionuclide. Activity is a quantity related to radioactivity. The SI unit of activity is the becquerel (Bq), equal to one reciprocal second. The becquerel is defined as the number of radioactive transformations per second that occur in a particular radioactive isotope. Its related non-SI unit equivalent is the Curie (Ci) which is transformations per second. Since the probability of radioactive decay for a given radionuclide is a fixed physical quantity (with some slight exceptions, see changing decay rates), the number of
Specific activity the radionuclide is given by where "m" is mass number of the radionuclide and "N" is the Avogadro constant. Specific radioactivity "a" is defined as radioactivity per unit mass of the radionuclide: In addition, decay constant "λ" is related to the half-life "T" by the following equation: Thus, specific radioactivity can also be described by This equation is simplified by When the unit of half-life converts a year For example, specific radioactivity of radium-226 with a half-life of 1600 years is obtained by This value derived from radium 226 was defined as unit of radioactivity known as Curie (Ci). Experimentally