The Smoky Bomb Threat by Peter Zimmerman - New York Times

[applegrove]

Op-Ed Contributor
The Smoky Bomb Threat
By PETER D. ZIMMERMAN
Published: December 19, 2006
The New York Times
London


THE exotic murder-by-polonium of the former K.G.B. spy Alexander Litvinenko has embroiled Russia, Britain and Germany in a diplomatic scuffle and a hunt for more traces of the lethal substance. But it also throws into question most of the previous analyses of “dirty bombs,” terrorist attacks using radioactive isotopes wrapped in explosives (or using other dispersion techniques) to spread radioactive material in crowded areas.

Essentially all analysts, myself included, played down the possibility of using alpha radiation — fast-moving helium nuclei ejected during the radioactive decay of certain isotopes, such as of polonium 210, the substance that killed Mr. Litvinenko — as a source of dirty bombs. We concentrated instead on isotopes that emit penetrating gamma rays, which are basically super-powered packets of light, hard to shield and effective at a yard or more.

The alpha radiation from polonium can be easily shielded — by a layer of aluminum foil, a sheet or two of paper, or the dead outer layer of skin. And so, the reasoning went, alpha radiation could not hurt you as long as the source stayed outside your body. Exactly. Mr. Litvinenko was apparently killed by polonium that he ate or drank or inhaled. That source was so physically small that it was hard to see, perhaps the size of a couple of grains of salt and weighing just a few millionths of a gram.

Dirty bombs based on gamma emitters, analysts have learned, can’t kill very many people. Mr. Litvinenko’s death tells us that “smoky bombs” based on alpha emitters very well could.

..........SNIP"

http://www.nytimes.com/2006/12/19/opinion/19zimmerman.html?th&emc=th