Decay Constant | Definition, Formula, & Facts - Britannica

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External Websites

• Institute of Physics - Decay constant, radioactive
• Engineering LibreTexts - The Decay Constants and Half-Lives
• National Center for Biotechnology Information - PubMed Central - Evidence against solar influence on nuclear decay constants
• CORE - Decay constants of heavy vector mesons at finite temperature (PDF)

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decay constant, proportionality between the size of a population of radioactive atoms and the rate at which the population decreases because of radioactive decay. Suppose N is the size of a population of radioactive atoms at a given time t, and dN is the amount by which the population decreases in time dt; then the rate of change is given by the equation dN/dt = −λN, where λ is the decay constant. Integration of this equation yields N = N0e−λt, where N0 is the size of an initial population of radioactive atoms at time t = 0. This shows that the population decays exponentially at a rate that depends on the decay constant. The time required for half of the original population of radioactive atoms to decay is called the half-life. The relationship between the half-life, T1/2, and the decay constant is given by T1/2 = 0.693/λ.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Erik Gregersen.