The Trinity Gadget: The First Atomic Bomb

The Gadget, the first atomic bomb, 1945.

The nuclear test of the first detonation of a nuclear weapon was codenamed Trinity, but the atomic device was nicknamed The Gadget. The date of the Trinity test is usually considered to be the beginning of the Atomic Age. The gadget was an implosion-type plutonium device, similar in design to the Fat Man bomb used three weeks later in the atomic bombing of Nagasaki, Japan.

The term “Gadget” was a laboratory euphemism for the bomb, from which the laboratory’s weapon physics division, “G Division”, took its name in August 1944. At that time it did not refer specifically to the Trinity Test device as it had yet to be developed, but once it was, it became the laboratory code name. The Trinity Gadget was

All those wires are attached to different explosives which burn at different frequencies. The trick of the 20 explosions is that they push the pieces of uranium (or plutonium) together to a ball with an over-critical mass, which explodes. They have to time this extremely accurately, however. Microseconds differences will make the ball lopsided and less effective. Part of the solution is to make each and every cable the same length which is why the Gadget looks like a ball of wires.

Assembly of the nuclear capsule began on 13 July 1945 at the McDonald Ranch House, where the master bedroom had been turned into a clean room. The polonium-beryllium “Urchin” initiator was assembled, and Louis Slotin placed it inside the two hemispheres of the plutonium core. Cyril Smith then placed the core in the uranium tamper plug, or “slug”. Air gaps were filled with 0.5-mil (0.013 mm) gold foil, and the two halves of the plug were held together with uranium washers and screws which fit smoothly into the domed ends of the plug. The completed capsule was then driven to the base of the