from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A white metallic transuranic element of the actinide series, having isotopes with mass numbers from 237 to 246 and half-lives from 25 minutes to 7,950 years. Its longest-lived isotopes, Am 241 and Am 243, are alpha-ray emitters used as radiation sources in research. Atomic number 95; specific gravity 11.7; valence 3, 4, 5, 6. See Table at element.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. The chemical element (symbol Am) with an atomic number of 95.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a radioactive transuranic metallic element; discovered by bombarding uranium with helium atoms


from The American Heritage® Dictionary of the English Language, 4th Edition

After America .

from Wiktionary, Creative Commons Attribution/Share-Alike License

From Americ(as) + -ium, by analogy with europium.


  • Barot wrote a letter to the leaders of al-Qaeda proposing that he would mine the small amount of radioactive material known as americium that can be found in ordinary smoke detectors and use it to build a radiological device.

    The Longest War

  • Smoke detectors, he learned, contain small amounts of a radio-active element called americium, while camping lanterns contain thorium.

  • Hahn diligently amassed this radioactive material by collecting small amounts from household products, such as americium from smoke detectors, thorium from camping lantern mantles, radium from clocks and tritium (as neutron moderator) from gun-sights.

    Greensboring® Greensboro, NC

  • Acord has therefore basically produced a conventional americium-beryllium neutron source from home-made materials.

    Archive 2009-04-01

  • In his presentation document to al-Qaeda, Barot said that the americium from around ten thousand smoke detectors would be needed to make the bomb effective and that once the device was detonated the subsequent radioactive cloud “has the potential to affect around 500 people.”

    The Longest War

  • In March 2002, Henry Kelly, President of the Federation of American Scientists, testified before the Senate Foreign Relations Committee on the possibility of constructing dirty bombs using three different radioactive elements -- cesium, cobalt and americium.

    Rizwan Ladha: The Real Deal With Cesium

  • Although all of these goals were demonstrated, the program was aborted before recycling of neptunium and americium was properly evaluated.

    Fast neutron reactors (FBR)

  • A terrorist could scatter a few ounces of americium with a conventional explosive in it any of the world's cities, contaminating a ten-block radius with radioactive poison.

    Joe Cirincione: Dirty Nuclear Business

  • Analysis of the material showed it was actually americium -- a highly radioactive substance.

    Joe Cirincione: Dirty Nuclear Business

  • General Atomics say that the MHR has a neutron spectrum is such and the TRISO fuel so stable that the reactor can be powered fully with separated transuranic wastes (neptunium, plutonium, americium and curium) from light water reactor used fuel.

    Small nuclear power reactors


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  • Am.

    December 16, 2007