natural radioactivity

https://doi.org/10.1351/goldbook.N04092
@[email protected] of naturally occurring @[email protected] in materials where the @[email protected] of that @[email protected] is natural.
Source:
PAC, 1982, 54, 1533. (Glossary of terms used in nuclear analytical chemistry (Provisional)) on page 1546 [Terms] [Paper]