| actinide series |
the series of chemical elements, mostly synthetic and all radioactive, that have from eighty-nine to 103 protons per atom. |
| actinium |
a radioactive chemical element of the rare-earth group that has eighty-nine protons in each nucleus. (symbol: Ac) |
| actinogen |
any of the radioactive chemical elements. |
| activate |
in physics, to cause radioactive properties in (a substance). [1/6 definitions] |
| americium |
a synthetic radioactive chemical element that has ninety-five protons in each nucleus. (symbol: Am) |
| astatine |
a highly radioactive chemical element of the halogen group that has eighty-five protons in each nucleus. (symbol: At) |
| atomic cocktail |
(informal) a dose of a liquid, taken orally, that contains a radioactive substance used in the diagnosis or treatment of cancer. |
| autoradiograph |
a picture produced on a film by placing it in contact with a radioactive substance. |
| berkelium |
a radioactive synthetic metal element of the actinide series that has ninety-seven protons in each nucleus. (symbol: Bk) |
| beta particle |
a high-speed positron or electron ejected from a nucleus in radioactive decay or fission. |
| californium |
a synthetic radioactive chemical element having ninety-eight protons in each nucleus. (symbol: Cf) |
| carbon 14 |
a radioactive isotope of carbon that has a half-life of about 5,700 years and whose presence in rock, fossils, and other archaeological specimens enables them to be dated. |
| curium |
a synthetic radioactive chemical element that has ninety-six protons in each nucleus. (symbol: Cm) |
| einsteinium |
a synthetic radioactive chemical element that has ninety-nine protons in each nucleus. (symbol: Es) |
| fallout |
the fall of radioactive particles, or the particles themselves, that result from a nuclear explosion. [1/2 definitions] |
| fermium |
a synthetic radioactive chemical element that has one hundred protons in each nucleus. (symbol: Fm) |
| francium |
a highly radioactive chemical element of the alkali metal group that has eighty-seven protons in each nucleus. (symbol: Fr) |
| gamma ray |
electromagnetic radiation of high energy and frequency, produced by reactions of radioactive atoms or by high energy electrons interacting with matter. |
| Geiger counter |
an instrument that detects radiation by means of a gas that ionizes when in the presence of radioactive emanations, and that also measures it by a device that counts the electrical pulses emitted by the ionized gas. |
| hahnium |
a synthetic radioactive chemical element that has 105 protons in each nucleus. (symbol: Ha) |
| half-life |
in physics, the time required for disintegration of half the atoms in a given quantity of radioactive material. |