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National Museum of Nuclear Science & History

Little Boy and Fat Man Photos Go Viral

Louis Slotin and Herb Lehr at the assembly of the Trinity "Gadget."  The uranium tamper is on the box in front of Lehr.
The New York Times (NYT) published an article this month on the public’s recent interest in photographs of the Little Boy and Fat Man bombs. As the NYT’s William Broad notes, some of the photographs have been online for years but only recently went “viral,” attracting the interest of tens of thousands of people. The websiteAlternateWars published images from the National Archives of Little Boy and Fat Man being loaded into the B-29s before the bombings of Hiroshima and Nagasaki. 
The Los Alamos National Laboratory has hundreds of historic photos online, including the one (above) that so amazed John Coster-Mullen, showing the uranium tamper for “Gadget.” Historian Alex Wellerstein explains, “There was uranium inside both the “Gadget” and Fat Man devices – in the tamper. The tamper was a sphere of uranium that encased the plutonium pit, which itself encased a polonium-beryllium neutron source, Russian-doll style…Its purpose was to hold together the core while the core did its best to try and explode. (It also helped reflect neutrons back into the core, which also worked to improve the efficiency.)” Wellerstein goes on, “There’s only one picture that shows it…and it is one of those things that you don’t even usually notice about that picture until someone points it out to you.”
There are lots of great hidden details in many of these photographs. Check them out and see for yourself!