Space Glossary Definition (English)
Radioactivity Defined
The following is in context to Space, because it's common for a single word to have multiple meanings you will find additional research links near the bottom of the page.
"Instability of some atomic nuclei, causing them to change spontaneously to a lower energy level or to modify the number of protons and neutrons they contain. The 3 "classical" types of radioactive emissions are (1) alpha particles, nuclei of helium (2) beta-rays, fast electrons and (3) gamma-rays, high-energy photons."
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Additional Radioactivity Definition Starting Points
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Expert Dictionary: Radioactivity
