Word: uranium
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...Pope and his team almost found nuclear fission in 1934 in the course of experiments in which, looking for radioactive transformations, they systematically bombarded one element after another with the newly discovered neutron. They missed by the thickness of the sheet of foil in which they wrapped their uranium sample; the foil blocked the fission fragments that their instruments would otherwise have recorded. It was a blessing in disguise. If fission had come to light in the mid-1930s, while the democracies still slept, Nazi Germany would have won a long lead toward building an atom bomb. In compensation, Fermi...
...fellow emigres--Hungarians Leo Szilard, Eugene Wigner, John von Neumann and Edward Teller, German Hans Bethe--formed the heart of the bomb squad. In 1939, still officially enemy aliens, Fermi and Szilard co-invented the nuclear reactor at Columbia University, sketching out a three-dimensional lattice of uranium slugs dropped into holes in black, greasy blocks of graphite moderator, with sliding neutron-absorbing cadmium control rods to regulate the chain reaction. Fermi, still mastering English, dubbed this elegantly simple machine a "pile...
...charted with his pocket slide rule. At 11:30 a.m., as was his custom, he stopped for lunch. The pile went critical in midafternoon with the full withdrawal of the control rods, and Fermi allowed himself a grin. He had proved the science of a chain reaction in uranium; from then on, building a bomb was mere engineering. He shut the pile down after 28 minutes of operation. Wigner had thought to buy a celebratory fiasco of Chianti, which supplied a toast. "For some time we had known that we were about to unlock a giant," Wigner would write. "Still...
...that by 1993 bin Laden had begun hunting for nuclear weapons. First on his shopping list was a Russian nuclear warhead he hoped to buy on the black market. He abandoned that effort when no warhead could be found. Instead, his agents began scouring former Soviet republics for enriched uranium and weapons components that could be used to set off the fuel...
Fortunately, "Osama's buyers weren't physicists, and the people selling to him were trying to rip him off," says an Energy Department official. The enriched uranium they were offered turned out to be low-grade reactor fuel unusable for a weapon. Another con man tried to sell them radioactive garbage, claiming it was "red mercury," a supposedly lethal Russian bomb the CIA says never existed. Frustrated, bin Laden instead settled on chemical weapons, which are easier to manufacture. Although U.S. intelligence officials have been unable to pinpoint hidden caches, they suspect that during a five-year stay in Sudan...