Rate of Radioactive Decay

The rate of radioactive decay, that is the number of disintegrations per unit time, is proportional to the number of radioactive nuclei in the sample. The half-life is the time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value. The mean lifetime (τ, “tau”) is the average lifetime of a radioactive particle before decay. The decay constant (λ, “lambda”) is the inverse of the mean lifetime.