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In nuclear physics, transient equilibrium is a situation in which equilibrium is reached by a parent-daughter radioactive isotope pair where the half-life of the daughter is shorter than the half-life of the parent. Contrary to secular equilibrium, the half-life of the daughter is not negligible compared to parent's half-life. An example of this is a molybdenum-99 generator producing technetium-99 for nuclear medicine diagnostic procedures. Such a generator is sometimes called a '' cow '' because the daughter product, in this case technetium-99, is milked at regular intervals.〔(transient equilibrium ) 〕 Transient equilibrium occurs after four half-lives, on average. ==Activity in transient equilibrium== The activity of the daughter is given by the Bateman equation: :, where and are the activity of the parent and daughter, respectively. and are the half-lives (inverses of reaction rates \lambda\ in the above equation modulo ln(2)) of the parent and daughter, respectively, and BR is the branching ratio. In transient equilibrium, the Bateman equation cannot be simplified by assuming the daughter's half-life is negligible compared to the parent's half-life. The ratio of daughter-to-parent activity is given by: :. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Transient equilibrium」の詳細全文を読む スポンサード リンク
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