Trinity (nuclear Test) - The Gadget

The Gadget

"The gadget" was the code name given to the first bomb tested. It was so called because it was not a deployable weapon and because revealing words like bomb were not used during the project for fear of espionage. It 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.

In the Fat Man design, a subcritical sphere of plutonium was placed in the center of a hollow sphere of high explosive. Numerous exploding-bridgewire detonators located on the surface of the high explosive were fired simultaneously to produce a powerful inward pressure on the core, squeezing it and increasing its density, resulting in a supercritical condition and a nuclear explosion. The actual eventual Fat Man and the "gadget" devices were not strictly "Fat Man type", as the design was modified into a production design, and both were strictly one-off prototypes.

The gadget was tested at Trinity Site, New Mexico, near Alamogordo. For the test, the gadget was lifted to the top of a 100-foot (30 m) bomb tower. It was feared by some that the Trinity test might "ignite" the earth's atmosphere, eliminating all life on the planet, although calculations had determined this was unlikely. Less wild estimates thought that New Mexico would be incinerated. Calculations showed that the yield of the device would be between 0 (if it did not work) and 20 kilotons of TNT. In the aftermath of the test, it appeared to have been a blast equivalent to 18 kt of TNT.