Curie - Curies As A Measure of Quantity

Curies As A Measure of Quantity

Curies are occasionally used to express a quantity of radioactive material rather than a decay rate, such as when one refers to 1 Ci of caesium-137. This may be interpreted as the number of atoms that would produce 1 Ci of radiation. The rules of radioactive decay may be used convert this to an actual number of atoms. They state that 1 Ci of radioactive atoms would follow the expression:

N (atoms) * λ (s-1) = 1 Ci = 3.7 × 1010 (Bq)

and so,

N = 3.7 × 1010 / λ

where λ is the decay constant in (s-1).

The use of Curies to measure quantity is unique in that 1 Ci of a nuclide will be fewer Curies at any later time.

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