Decay constant

Decay constant is a parameter in the mathematical expression of the time dependence of a decaying quantity. It is the inverse of the mean lifetime. The decay constant is the probability per unit time that a particle will decay, regardless of how long it has existed.

Definition

The decay constant (λ) of a decaying quantity is defined as the fraction of the quantity which decays in a certain time (the mean lifetime). It is equal to the inverse of the mean lifetime (τ):

λ = 1/τ

The decay constant is a measure of the probability per unit time that a particle will decay. It is a fundamental parameter in the mathematical description of exponential decay.

Applications

The decay constant is used in the calculation of the half-life (t_1/2) of a decaying quantity. The half-life is the time it takes for half of the quantity to decay. It is related to the decay constant by the equation:

t_1/2 = ln(2)/λ

The decay constant is also used in the calculation of the activity (A) of a radioactive substance. The activity is the number of decays per unit time. It is related to the decay constant and the number of particles (N) by the equation:

A = λN

See also

• Exponential decay
• Half-life
• Mean lifetime
• Activity (radioactivity)
• Number of particles

References

Decay constant Resources
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