National Museum of Nuclear Science and Technology

This was a really nice museum, fittingly located in Albuquerque. I suppose it might be better sited in Los Alamos, but Albuquerque is a much more visited city and sitting on the edge of Kirtland Air force Base is also a plus for the museum. It contains lots of exhibits of the history of the US atomic bomb development in New Mexico, the science behind it, and the people and places that dropped it during the war.

There were three star exhibits: reconstructions of the first three atomic bombs. Above the the 'gadget' detonated at the Trinity site near Almagordo as a proof of concept.

There are only two ever actually used to kill people during the war. Here is a mockup of Fat man, the bomb dropped on Nagasaki on August 9, 1945. It is an implosion type bomb. This means that the fissile material, plutonium, is  separated to prevent it going critical and, at detonation, it is all compressed together by shaped conventional explosives that surround it. This gives it the rounded, 'fat' shape and, hence, the name.

The other casing mocked up for display is 'Little Boy'. This is gun type design. The idea is that the fissile material, in this case, uranium, is divided into two sub-critical pieces that are fired at one another to detonate.

The yield of both of these bombs is the equivalent of about 23 kilo tons of TNT. You can read more information on Wikipedia here and here.

The naming of the two bombs is also an interesting bit of Americana.

The gun-type and implosion-type designs were codenamed "Thin Man" and "Fat Man" respectively. These code names were created by Robert Serber, a former student of Oppenheimer's who worked on the Manhattan Project. He chose them based on their design shapes; the Thin Man was a very long device, and the name came from the Dashiell Hammett detective novel The Thin Man and series of movies. The Fat Man was round and fat and was named after Sydney Greenstreet's character in Hammett's The Maltese Falcon. Little Boy came last as a variation of Thin Man.^[6]