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Secular Equilibrium Daughter Activity Buildup Calculator

A_d(t) = A_parent × (1 − e^(−λ_d t)) — daughter buildup.

Calculates the activity of a daughter nuclide at time t in secular equilibrium (parent half-life >> daughter half-life). Daughter activity asymptotically equals parent activity.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

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Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

A_d(t) = A_parent × (1 − exp(−λ_d × t)); λ_d = ln 2 / T½_d

In depth

Calculates the activity of a daughter nuclide at time t in secular equilibrium (parent half-life >> daughter half-life). Daughter activity asymptotically equals parent activity.