## activity, $$A$$

of a radioactive material
Synonyms: decay rate, disintegration rate
https://doi.org/10.1351/goldbook.A00114
The number of @N04227@ occurring in a given quantity of material in a small time interval, divided by that time interval. Often, this term is referred to as @A00019@. Symbol $$A=- \frac{\mathrm{d}N}{\mathrm{d}t}$$. Synonymous with disintegration rate or decay rate.
Sources:
Green Book, 2nd ed., p. 22 [Terms] [Book]
PAC, 1994, 66, 2513. (Nomenclature for radioanalytical chemistry (IUPAC Recommendations 1994)) on page 2515 [Terms] [Paper]
PAC, 1996, 68, 957. (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 960 [Terms] [Paper]