衰变产物

由鉛212至鉛208的衰變鏈

在原子核物理學中，衰變產物(也稱至子同位素)是一個元素經過輻射衰變後剩下來的核素。輻射衰變通常涉及很多過程(衰變鏈)。例如，鈾238(U-238)衰變至釷234(Th-234)，釷234(Th-234)再衰變成鏷234(Pa-234)，而鏷234(Pa-234)再衰變成…，再衰變成鉛206(Pb-206)（穩定）:

${\mbox{U-238}}\rightarrow \overbrace {\underbrace {\mbox{Th-234}} _{\mbox{daughter of U-238}}\rightarrow \underbrace {\mbox{Pa-234m}} _{\mbox{granddaughter of U-238}}\rightarrow \ldots \rightarrow {\mbox{Pb-206}}} ^{\begin{array}{c}{\mbox{decay products of U-238}}\end{array}}$

$v$

在這例子中，

• 釷234，鏷234m，…，鉛206是鈾238的衰變產物；
• 釷234是鈾238的至子同位素；
• 鏷234m (234 metastable)是鈾238的[至孫同位素][?]。

These might also be referred to as the daughter products of U-238.

Decay products are important in understanding radioactive decay and the management of radioactive waste.

For elements above lead in atomic number, the decay chain typically ends with an isotope of lead.

In many cases members of the decay chain are far more radioactive than the original nuclide. Thus, although uranium is not dangerously radioactive when pure, some pieces of naturally-occurring pitchblende are quite dangerous owing to their radium content. Similarly, thorium gas mantles are very slightly radioactive when new, but become far more radioactive after only a few months of storage.

Although it cannot be predicted whether any given atom of a radioactive substance will decay at any given time, the decay products of a radioactive substance are extremely predictable. Because of this, decay products are important to scientists in many fields who need to know the quantity or type of the parent product. Such studies are done to measure pollution levels (in and around nuclear facilities) and for other matters.